<html><head><title>WG14/N1256 Septermber 7, 2007 ISO/IEC 9899:TC3</title></head><body>
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WG14/N1256 Committee Draft -- Septermber 7, 2007 ISO/IEC 9899:TC3
<li><a href="#6.4.9"> 6.4.9 Comments</a>
</ul>
<li><a href="#6.5"> 6.5 Expressions</a>
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<ul>
<li><a href="#6.5.1"> 6.5.1 Primary expressions</a>
<li><a href="#6.5.2"> 6.5.2 Postfix operators</a>
<li><a href="#6.10.4"> 6.10.4 Line control</a>
<li><a href="#6.10.5"> 6.10.5 Error directive</a>
<li><a href="#6.10.6"> 6.10.6 Pragma directive</a>
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<li><a href="#6.10.7"> 6.10.7 Null directive</a>
<li><a href="#6.10.8"> 6.10.8 Predefined macro names</a>
<li><a href="#6.10.9"> 6.10.9 Pragma operator</a>
<ul>
<li><a href="#7.8.1"> 7.8.1 Macros for format specifiers</a>
<li><a href="#7.8.2"> 7.8.2 Functions for greatest-width integer types</a>
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</ul>
<li><a href="#7.9"> 7.9 Alternative spellings <iso646.h></a>
<li><a href="#7.10"> 7.10 Sizes of integer types <limits.h></a>
<li><a href="#7.19.6"> 7.19.6 Formatted input/output functions</a>
<li><a href="#7.19.7"> 7.19.7 Character input/output functions</a>
<li><a href="#7.19.8"> 7.19.8 Direct input/output functions</a>
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<li><a href="#7.19.9"> 7.19.9 File positioning functions</a>
<li><a href="#7.19.10"> 7.19.10 Error-handling functions</a>
</ul>
<li><a href="#7.26.7"> 7.26.7 Boolean type and values <stdbool.h></a>
<li><a href="#7.26.8"> 7.26.8 Integer types <stdint.h></a>
<li><a href="#7.26.9"> 7.26.9 Input/output <stdio.h></a>
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<li><a href="#7.26.10"> 7.26.10 General utilities <stdlib.h></a>
<li><a href="#7.26.11"> 7.26.11 String handling <string.h></a>
<li><a href="#7.26.12"> 7.26.12 Extended multibyte and wide character utilities <wchar.h></a>
<li><a href="#F.1"> F.1 Introduction</a>
<li><a href="#F.2"> F.2 Types</a>
<li><a href="#F.3"> F.3 Operators and functions</a>
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<li><a href="#F.4"> F.4 Floating to integer conversion</a>
<li><a href="#F.5"> F.5 Binary-decimal conversion</a>
<li><a href="#F.6"> F.6 Contracted expressions</a>
</ul>
<li><a href="#Bibliography">Bibliography</a>
<li><a href="#Index">Index</a>
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</ul>
<a name="Foreword" href="#Foreword"><h2>Foreword</h2></a>
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ISO (the International Organization for Standardization) and IEC (the International
Electrotechnical Commission) form the specialized system for worldwide
standardization. National bodies that are member of ISO or IEC participate in the
technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also
take part in the work.
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International Standards are drafted in accordance with the rules given in the ISO/IEC
Directives, Part 3.
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In the field of information technology, ISO and IEC have established a joint technical
committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical
committee are circulated to national bodies for voting. Publication as an International
Standard requires approval by at least 75% of the national bodies casting a vote.
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International Standard ISO/IEC 9899 was prepared by Joint Technical Committee
ISO/IEC JTC 1, Information technology, Subcommittee SC 22, Programming languages,
their environments and system software interfaces. The Working Group responsible for
http://www.open-std.org/JTC1/SC22/WG14/ containing additional
information relevant to this standard such as a Rationale for many of the decisions made
during its preparation and a log of Defect Reports and Responses.
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This second edition cancels and replaces the first edition, ISO/IEC 9899:1990, as
amended and corrected by ISO/IEC 9899/COR1:1994, ISO/IEC 9899/AMD1:1995, and
ISO/IEC 9899/COR2:1996. Major changes from the previous edition include:
<li> complex (and imaginary) support in <a href="#7.3"><complex.h></a>
<li> type-generic math macros in <a href="#7.22"><tgmath.h></a>
<li> the long long int type and library functions
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<li> increased minimum translation limits
<li> additional floating-point characteristics in <a href="#7.7"><float.h></a>
<li> remove implicit int
<li> boolean type in <a href="#7.16"><stdbool.h></a>
<li> idempotent type qualifiers
<li> empty macro arguments
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<li> new structure type compatibility rules (tag compatibility)
<li> additional predefined macro names
<li> _Pragma preprocessing operator
<li> return without expression not permitted in function that returns a value (and vice
versa)
</ul>
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Annexes D and F form a normative part of this standard; annexes A, B, C, E, G, H, I, J,
the bibliography, and the index are for information only. In accordance with Part 3 of the
ISO/IEC Directives, this foreword, the introduction, notes, footnotes, and examples are
also for information only.
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<a name="Introduction" href="#Introduction"><h2>Introduction</h2></a>
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With the introduction of new devices and extended character sets, new features may be
added to this International Standard. Subclauses in the language and library clauses warn
implementors and programmers of usages which, though valid in themselves, may
conflict with future additions.
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Certain features are obsolescent, which means that they may be considered for
withdrawal in future revisions of this International Standard. They are retained because
of their widespread use, but their use in new implementations (for implementation
features) or new programs (for language [<a href="#6.11">6.11</a>] or library features [<a href="#7.26">7.26</a>]) is discouraged.
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This International Standard is divided into four major subdivisions:
<ul>
<li> preliminary elements (clauses 1-4);
<li> the language syntax, constraints, and semantics (clause 6);
<li> the library facilities (clause 7).
</ul>
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Examples are provided to illustrate possible forms of the constructions described.
Footnotes are provided to emphasize consequences of the rules described in that
subclause or elsewhere in this International Standard. References are used to refer to
implementors. Annexes provide additional information and summarize the information
contained in this International Standard. A bibliography lists documents that were
referred to during the preparation of the standard.
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The language clause (clause 6) is derived from ''The C Reference Manual''.
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The library clause (clause 7) is based on the 1984 /usr/group Standard.
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<h1>Programming languages -- C</h1>
<a name="1" href="#1"><h2>1. Scope</h2></a>
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This International Standard specifies the form and establishes the interpretation of
programs written in the C programming language.<sup><a href="#note1"><b>1)</b></a></sup> It specifies
<ul>
<li> the representation of output data produced by C programs;
<li> the restrictions and limits imposed by a conforming implementation of C.
</ul>
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This International Standard does not specify
<ul>
<li> the mechanism by which C programs are transformed for use by a data-processing
specific data-processing system or the capacity of a particular processor;
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<li> all minimal requirements of a data-processing system that is capable of supporting a
conforming implementation.
</small>
<a name="2" href="#2"><h2>2. Normative references</h2></a>
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The following normative documents contain provisions which, through reference in this
text, constitute provisions of this International Standard. For dated references,
subsequent amendments to, or revisions of, any of these publications do not apply.
documents indicated below. For undated references, the latest edition of the normative
document referred to applies. Members of ISO and IEC maintain registers of currently
valid International Standards.
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ISO 31-11:1992, Quantities and units -- Part 11: Mathematical signs and symbols for
use in the physical sciences and technology.
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ISO/IEC 646, Information technology -- ISO 7-bit coded character set for information
interchange.
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ISO/IEC 2382-1:1993, Information technology -- Vocabulary -- Part 1: Fundamental
terms.
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ISO 4217, Codes for the representation of currencies and funds.
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ISO 8601, Data elements and interchange formats -- Information interchange --
Representation of dates and times.
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ISO/IEC 10646 (all parts), Information technology -- Universal Multiple-Octet Coded
Character Set (UCS).
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IEC 60559:1989, Binary floating-point arithmetic for microprocessor systems (previously
designated IEC 559:1989).
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<a name="3" href="#3"><h2>3. Terms, definitions, and symbols</h2></a>
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For the purposes of this International Standard, the following definitions apply. Other
terms are defined where they appear in italic type or on the left side of a syntax rule.
Terms explicitly defined in this International Standard are not to be presumed to refer
defined in this International Standard are to be interpreted according to ISO 31-11.
<a name="3.1" href="#3.1"><h3>3.1</h3></a>
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access
<execution-time action> to read or modify the value of an object
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NOTE 1 Where only one of these two actions is meant, ''read'' or ''modify'' is used.
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NOTE 2 "Modify'' includes the case where the new value being stored is the same as the previous value.
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NOTE 3 Expressions that are not evaluated do not access objects.
<a name="3.2" href="#3.2"><h3>3.2</h3></a>
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alignment
requirement that objects of a particular type be located on storage boundaries with
addresses that are particular multiples of a byte address
<a name="3.3" href="#3.3"><h3>3.3</h3></a>
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argument
actual argument
actual parameter (deprecated)
by the parentheses in a function-like macro invocation
<a name="3.4" href="#3.4"><h3>3.4</h3></a>
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behavior
external appearance or action
<a name="3.4.1" href="#3.4.1"><h4>3.4.1</h4></a>
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implementation-defined behavior
unspecified behavior where each implementation documents how the choice is made
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EXAMPLE An example of implementation-defined behavior is the propagation of the high-order bit
when a signed integer is shifted right.
<a name="3.4.2" href="#3.4.2"><h4>3.4.2</h4></a>
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locale-specific behavior
behavior that depends on local conventions of nationality, culture, and language that each
implementation documents
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EXAMPLE An example of locale-specific behavior is whether the islower function returns true for
characters other than the 26 lowercase Latin letters.
<a name="3.4.3" href="#3.4.3"><h4>3.4.3</h4></a>
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undefined behavior
behavior, upon use of a nonportable or erroneous program construct or of erroneous data,
for which this International Standard imposes no requirements
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NOTE Possible undefined behavior ranges from ignoring the situation completely with unpredictable
results, to behaving during translation or program execution in a documented manner characteristic of the
environment (with or without the issuance of a diagnostic message), to terminating a translation or
execution (with the issuance of a diagnostic message).
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EXAMPLE An example of undefined behavior is the behavior on integer overflow.
<a name="3.4.4" href="#3.4.4"><h4>3.4.4</h4></a>
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unspecified behavior
use of an unspecified value, or other behavior where this International Standard provides
two or more possibilities and imposes no further requirements on which is chosen in any
instance
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EXAMPLE An example of unspecified behavior is the order in which the arguments to a function are
evaluated.
<a name="3.5" href="#3.5"><h3>3.5</h3></a>
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bit
unit of data storage in the execution environment large enough to hold an object that may
have one of two values
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NOTE It need not be possible to express the address of each individual bit of an object.
<a name="3.6" href="#3.6"><h3>3.6</h3></a>
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byte
addressable unit of data storage large enough to hold any member of the basic character
set of the execution environment
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NOTE 1 It is possible to express the address of each individual byte of an object uniquely.
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NOTE 2 A byte is composed of a contiguous sequence of bits, the number of which is implementation-
defined. The least significant bit is called the low-order bit; the most significant bit is called the high-order
bit.
<a name="3.7" href="#3.7"><h3>3.7</h3></a>
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character
<abstract> member of a set of elements used for the organization, control, or
representation of data
<a name="3.7.1" href="#3.7.1"><h4>3.7.1</h4></a>
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character
single-byte character
<C> bit representation that fits in a byte
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<a name="3.7.2" href="#3.7.2"><h4>3.7.2</h4></a>
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multibyte character
sequence of one or more bytes representing a member of the extended character set of
either the source or the execution environment
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NOTE The extended character set is a superset of the basic character set.
<a name="3.7.3" href="#3.7.3"><h4>3.7.3</h4></a>
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wide character
bit representation that fits in an object of type wchar_t, capable of representing any
character in the current locale
<a name="3.8" href="#3.8"><h3>3.8</h3></a>
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constraint
restriction, either syntactic or semantic, by which the exposition of language elements is
to be interpreted
<a name="3.9" href="#3.9"><h3>3.9</h3></a>
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correctly rounded result
representation in the result format that is nearest in value, subject to the current rounding
mode, to what the result would be given unlimited range and precision
<a name="3.10" href="#3.10"><h3>3.10</h3></a>
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diagnostic message
message belonging to an implementation-defined subset of the implementation's message
output
<a name="3.11" href="#3.11"><h3>3.11</h3></a>
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forward reference
reference to a later subclause of this International Standard that contains additional
information relevant to this subclause
<a name="3.12" href="#3.12"><h3>3.12</h3></a>
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implementation
particular set of software, running in a particular translation environment under particular
control options, that performs translation of programs for, and supports execution of
functions in, a particular execution environment
<a name="3.13" href="#3.13"><h3>3.13</h3></a>
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implementation limit
restriction imposed upon programs by the implementation
<a name="3.14" href="#3.14"><h3>3.14</h3></a>
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object
region of data storage in the execution environment, the contents of which can represent
values
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NOTE When referenced, an object may be interpreted as having a particular type; see <a href="#6.3.2.1">6.3.2.1</a>.
<a name="3.15" href="#3.15"><h3>3.15</h3></a>
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parameter
formal parameter
formal argument (deprecated)
parentheses immediately following the macro name in a function-like macro definition
<a name="3.16" href="#3.16"><h3>3.16</h3></a>
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recommended practice
specification that is strongly recommended as being in keeping with the intent of the
standard, but that may be impractical for some implementations
<a name="3.17" href="#3.17"><h3>3.17</h3></a>
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value
precise meaning of the contents of an object when interpreted as having a specific type
<a name="3.17.1" href="#3.17.1"><h4>3.17.1</h4></a>
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implementation-defined value
unspecified value where each implementation documents how the choice is made
<a name="3.17.2" href="#3.17.2"><h4>3.17.2</h4></a>
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indeterminate value
either an unspecified value or a trap representation
<a name="3.17.3" href="#3.17.3"><h4>3.17.3</h4></a>
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unspecified value
valid value of the relevant type where this International Standard imposes no
requirements on which value is chosen in any instance
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NOTE An unspecified value cannot be a trap representation.
<a name="3.18" href="#3.18"><h3>3.18</h3></a>
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??? x???
ceiling of x: the least integer greater than or equal to x
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EXAMPLE ???2.4??? is 3, ???-2.4??? is -2.
<a name="3.19" href="#3.19"><h3>3.19</h3></a>
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??? x???
floor of x: the greatest integer less than or equal to x
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EXAMPLE ???2.4??? is 2, ???-2.4??? is -3.
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<a name="4" href="#4"><h2>4. Conformance</h2></a>
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In this International Standard, ''shall'' is to be interpreted as a requirement on an
implementation or on a program; conversely, ''shall not'' is to be interpreted as a
prohibition.
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If a ''shall'' or ''shall not'' requirement that appears outside of a constraint is violated, the
behavior is undefined. Undefined behavior is otherwise indicated in this International
Standard by the words ''undefined behavior'' or by the omission of any explicit definition
of behavior. There is no difference in emphasis among these three; they all describe
''behavior that is undefined''.
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A program that is correct in all other aspects, operating on correct data, containing
unspecified behavior shall be a correct program and act in accordance with <a href="#5.1.2.3">5.1.2.3</a>.
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The implementation shall not successfully translate a preprocessing translation unit
containing a #error preprocessing directive unless it is part of a group skipped by
conditional inclusion.
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A strictly conforming program shall use only those features of the language and library
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.
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The two forms of conforming implementation are hosted and freestanding. A conforming
hosted implementation shall accept any strictly conforming program. A conforming
freestanding implementation shall accept any strictly conforming program that does not
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A conforming program is one that is acceptable to a conforming implementation.<sup><a href="#note4"><b>4)</b></a></sup>
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An implementation shall be accompanied by a document that defines all implementation-
defined and locale-specific characteristics and all extensions.
<p><b> Forward references</b>: conditional inclusion (<a href="#6.10.1">6.10.1</a>), error directive (<a href="#6.10.5">6.10.5</a>),
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<h6>footnotes</h6>
<p><small><a name="note2" href="#note2">2)</a> A strictly conforming program can use conditional features (such as those in <a href="#F">annex F</a>) provided the
</small>
<a name="5" href="#5"><h2>5. Environment</h2></a>
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An implementation translates C source files and executes C programs in two data-
processing-system environments, which will be called the translation environment and
the execution environment in this International Standard. Their characteristics define and
<a name="5.1.1" href="#5.1.1"><h4>5.1.1 Translation environment</h4></a>
<a name="5.1.1.1" href="#5.1.1.1"><h5>5.1.1.1 Program structure</h5></a>
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A C program need not all be translated at the same time. The text of the program is kept
in units called source files, (or preprocessing files) in this International Standard. A
source file together with all the headers and source files included via the preprocessing
preprocessing directives (<a href="#6.10">6.10</a>).
<a name="5.1.1.2" href="#5.1.1.2"><h5>5.1.1.2 Translation phases</h5></a>
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The precedence among the syntax rules of translation is specified by the following
phases.<sup><a href="#note5"><b>5)</b></a></sup>
<ol>
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<li> Each instance of a backslash character (\) immediately followed by a new-line
character is deleted, splicing physical source lines to form logical source lines.
Only the last backslash on any physical source line shall be eligible for being part
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<h6>footnotes</h6>
<p><small><a name="note5" href="#note5">5)</a> Implementations shall behave as if these separate phases occur, even though many are typically folded
</small>
<a name="5.1.1.3" href="#5.1.1.3"><h5>5.1.1.3 Diagnostics</h5></a>
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A conforming implementation shall produce at least one diagnostic message (identified in
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.<sup><a href="#note8"><b>8)</b></a></sup>
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EXAMPLE An implementation shall issue a diagnostic for the translation unit:
<pre>
char i;
</small>
<a name="5.1.2" href="#5.1.2"><h4>5.1.2 Execution environments</h4></a>
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Two execution environments are defined: freestanding and hosted. In both cases,
program startup occurs when a designated C function is called by the execution
environment. All objects with static storage duration shall be initialized (set to their
<p><b> Forward references</b>: storage durations of objects (<a href="#6.2.4">6.2.4</a>), initialization (<a href="#6.7.8">6.7.8</a>).
<a name="5.1.2.1" href="#5.1.2.1"><h5>5.1.2.1 Freestanding environment</h5></a>
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In a freestanding environment (in which C program execution may take place without any
benefit of an operating system), the name and type of the function called at program
startup are implementation-defined. Any library facilities available to a freestanding
program, other than the minimal set required by clause 4, are implementation-defined.
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The effect of program termination in a freestanding environment is implementation-
defined.
<a name="5.1.2.2" href="#5.1.2.2"><h5>5.1.2.2 Hosted environment</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A hosted environment need not be provided, but shall conform to the following
specifications if present.
-<!--page 24 indent 4-->
+<!--page 24 -->
<a name="5.1.2.2.1" href="#5.1.2.2.1"><h5>5.1.2.2.1 Program startup</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The function called at program startup is named main. The implementation declares no
prototype for this function. It shall be defined with a return type of int and with no
parameters:
<pre>
int main(int argc, char *argv[]) { /* ... */ }</pre>
or equivalent;<sup><a href="#note9"><b>9)</b></a></sup> or in some other implementation-defined manner.
-<p><!--para 2-->
+<p><!--para 2 -->
If they are declared, the parameters to the main function shall obey the following
constraints:
<ul>
</small>
<a name="5.1.2.2.2" href="#5.1.2.2.2"><h5>5.1.2.2.2 Program execution</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In a hosted environment, a program may use all the functions, macros, type definitions,
and objects described in the library clause (clause 7).
-<!--page 25 indent 4-->
+<!--page 25 -->
<a name="5.1.2.2.3" href="#5.1.2.2.3"><h5>5.1.2.2.3 Program termination</h5></a>
-<p><!--para 1-->
+<p><!--para 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;<sup><a href="#note10"><b>10)</b></a></sup> reaching the } that terminates the
</small>
<a name="5.1.2.3" href="#5.1.2.3"><h5>5.1.2.3 Program execution</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The semantic descriptions in this International Standard describe the behavior of an
abstract machine in which issues of optimization are irrelevant.
-<p><!--para 2-->
+<p><!--para 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,<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
shall have taken place. (A summary of the sequence points is given in <a href="#C">annex C</a>.)
-<p><!--para 3-->
+<p><!--para 3 -->
In the abstract machine, all expressions are evaluated as specified by the semantics. An
actual implementation need not evaluate part of an expression if it can deduce that its
value is not used and that no needed side effects are produced (including any caused by
calling a function or accessing a volatile object).
-<p><!--para 4-->
+<p><!--para 4 -->
When the processing of the abstract machine is interrupted by receipt of a signal, only the
values of objects as of the previous sequence point may be relied on. Objects that may be
modified between the previous sequence point and the next sequence point need not have
received their correct values yet.
-<p><!--para 5-->
+<p><!--para 5 -->
The least requirements on a conforming implementation are:
<ul>
<li> At sequence points, volatile objects are stable in the sense that previous accesses are
-<!--page 26 indent 5-->
+<!--page 26 -->
<li> At program termination, all data written into files shall be identical to the result that
execution of the program according to the abstract semantics would have produced.
<li> The input and output dynamics of interactive devices shall take place as specified in
appear as soon as possible, to ensure that prompting messages actually appear prior to
a program waiting for input.
</ul>
-<p><!--para 6-->
+<p><!--para 6 -->
What constitutes an interactive device is implementation-defined.
-<p><!--para 7-->
+<p><!--para 7 -->
More stringent correspondences between abstract and actual semantics may be defined by
each implementation.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 1 An implementation might define a one-to-one correspondence between abstract and actual
semantics: at every sequence point, the values of the actual objects would agree with those specified by the
abstract semantics. The keyword volatile would then be redundant.
-<p><!--para 9-->
+<p><!--para 9 -->
Alternatively, an implementation might perform various optimizations within each translation unit, such
that the actual semantics would agree with the abstract semantics only when making function calls across
translation unit boundaries. In such an implementation, at the time of each function entry and function
would require explicit specification of volatile storage, as well as other implementation-defined
restrictions.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 2 In executing the fragment
<pre>
char c1, c2;
overflow, or with overflow wrapping silently to produce the correct result, the actual execution need only
produce the same result, possibly omitting the promotions.
-<p><!--para 11-->
+<p><!--para 11 -->
EXAMPLE 3 Similarly, in the fragment
<pre>
float f1, f2;
the multiplication may be executed using single-precision arithmetic if the implementation can ascertain
that the result would be the same as if it were executed using double-precision arithmetic (for example, if d
were replaced by the constant 2.0, which has type double).
-<!--page 27 indent 5-->
-<p><!--para 12-->
+<!--page 27 -->
+<p><!--para 12 -->
EXAMPLE 4 Implementations employing wide registers have to take care to honor appropriate
semantics. Values are independent of whether they are represented in a register or in memory. For
example, an implicit spilling of a register is not permitted to alter the value. Also, an explicit store and load
d2 = (float) expression;</pre>
the values assigned to d1 and d2 are required to have been converted to float.
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 5 Rearrangement for floating-point expressions is often restricted because of limitations in
precision as well as range. The implementation cannot generally apply the mathematical associative rules
for addition or multiplication, nor the distributive rule, because of roundoff error, even in the absence of
z = x + x * y; // not equivalent to z = x * (1.0 + y);
y = x / 5.0; // not equivalent to y = x * 0.2;</pre>
-<p><!--para 14-->
+<p><!--para 14 -->
EXAMPLE 6 To illustrate the grouping behavior of expressions, in the following fragment
<pre>
int a, b;
in which overflow silently generates some value and where positive and negative overflows cancel, the
above expression statement can be rewritten by the implementation in any of the above ways because the
same result will occur.
-<!--page 28 indent 5-->
-<p><!--para 15-->
+<!--page 28 -->
+<p><!--para 15 -->
EXAMPLE 7 The grouping of an expression does not completely determine its evaluation. In the
following fragment
<pre>
<p><b> Forward references</b>: expressions (<a href="#6.5">6.5</a>), type qualifiers (<a href="#6.7.3">6.7.3</a>), statements (<a href="#6.8">6.8</a>), the
signal function (<a href="#7.14">7.14</a>), files (<a href="#7.19.3">7.19.3</a>).
-<!--page 29 indent 4-->
+<!--page 29 -->
<h6>footnotes</h6>
<p><small><a name="note11" href="#note11">11)</a> The IEC 60559 standard for binary floating-point arithmetic requires certain user-accessible status
<a name="5.2" href="#5.2"><h3>5.2 Environmental considerations</h3></a>
<a name="5.2.1" href="#5.2.1"><h4>5.2.1 Character sets</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Two sets of characters and their associated collating sequences shall be defined: the set in
which source files are written (the source character set), and the set interpreted in the
execution environment (the execution character set). Each set is further divided into a
locale-specific members (which are not members of the basic character set) called
extended characters. The combined set is also called the extended character set. The
values of the members of the execution character set are implementation-defined.
-<p><!--para 2-->
+<p><!--para 2 -->
In a character constant or string literal, members of the execution character set shall be
represented by corresponding members of the source character set or by escape
sequences consisting of the backslash \ followed by one or more characters. A byte with
all bits set to 0, called the null character, shall exist in the basic execution character set; it
is used to terminate a character string.
-<p><!--para 3-->
+<p><!--para 3 -->
Both the basic source and basic execution character sets shall have the following
members: the 26 uppercase letters of the Latin alphabet
<pre>
control characters representing alert, backspace, carriage return, and new line. If any
other characters are encountered in a source file (except in an identifier, a character
constant, a string literal, a header name, a comment, or a preprocessing token that is never
-<!--page 30 indent 4-->
+<!--page 30 -->
converted to a token), the behavior is undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
A letter is an uppercase letter or a lowercase letter as defined above; in this International
Standard the term does not include other characters that are letters in other alphabets.
-<p><!--para 5-->
+<p><!--para 5 -->
The universal character name construct provides a way to name other characters.
<p><b> Forward references</b>: universal character names (<a href="#6.4.3">6.4.3</a>), character constants (<a href="#6.4.4.4">6.4.4.4</a>),
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"><h5>5.2.1.1 Trigraph sequences</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Before any other processing takes place, each occurrence of one of the following
sequences of three characters (called trigraph sequences<sup><a href="#note12"><b>12)</b></a></sup>) is replaced with the
corresponding single character.
??/ \ ??< { ??- ~</pre>
No other trigraph sequences exist. Each ? that does not begin one of the trigraphs listed
above is not changed.
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE 1
<pre>
??=define arraycheck(a, b) a??(b??) ??!??! b??(a??)</pre>
<pre>
#define arraycheck(a, b) a[b] || b[a]</pre>
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE 2 The following source line
<pre>
printf("Eh???/n");</pre>
</small>
<a name="5.2.1.2" href="#5.2.1.2"><h5>5.2.1.2 Multibyte characters</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The source character set may contain multibyte characters, used to represent members of
the extended character set. The execution character set may also contain multibyte
characters, which need not have the same encoding as for the source character set. For
<li> The presence, meaning, and representation of any additional members is locale-
specific.
-<!--page 31 indent 4-->
+<!--page 31 -->
<li> A multibyte character set may have a state-dependent encoding, wherein each
sequence of multibyte characters begins in an initial shift state and enters other
locale-specific shift states when specific multibyte characters are encountered in the
<li> A byte with all bits zero shall be interpreted as a null character independent of shift
state. Such a byte shall not occur as part of any other multibyte character.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
For source files, the following shall hold:
<ul>
<li> An identifier, comment, string literal, character constant, or header name shall begin
</ul>
<a name="5.2.2" href="#5.2.2"><h4>5.2.2 Character display semantics</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The active position is that location on a display device where the next character output by
the fputc function would appear. The intent of writing a printing character (as defined
by the isprint function) to a display device is to display a graphic representation of
position on the current line. The direction of writing is locale-specific. If the active
position is at the final position of a line (if there is one), the behavior of the display device
is unspecified.
-<p><!--para 2-->
+<p><!--para 2 -->
Alphabetic escape sequences representing nongraphic characters in the execution
character set are intended to produce actions on display devices as follows:
\a (alert) Produces an audible or visible alert without changing the active position.
on the current line. If the active position is at or past the last defined horizontal
tabulation position, the behavior of the display device is unspecified.</pre>
\v (vertical tab) Moves the active position to the initial position of the next vertical
-<!--page 32 indent 4-->
-<p><!--para 3-->
+<!--page 32 -->
+<p><!--para 3 -->
<pre>
tabulation position. If the active position is at or past the last defined vertical
tabulation position, the behavior of the display device is unspecified.</pre>
<p><b> Forward references</b>: the isprint function (<a href="#7.4.1.8">7.4.1.8</a>), the fputc function (<a href="#7.19.7.3">7.19.7.3</a>).
<a name="5.2.3" href="#5.2.3"><h4>5.2.3 Signals and interrupts</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Functions shall be implemented such that they may be interrupted at any time by a signal,
or may be called by a signal handler, or both, with no alteration to earlier, but still active,
invocations' control flow (after the interruption), function return values, or objects with
per-invocation basis.
<a name="5.2.4" href="#5.2.4"><h4>5.2.4 Environmental limits</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Both the translation and execution environments constrain the implementation of
language translators and libraries. The following summarizes the language-related
environmental limits on a conforming implementation; the library-related limits are
discussed in clause 7.
<a name="5.2.4.1" href="#5.2.4.1"><h5>5.2.4.1 Translation limits</h5></a>
-<p><!--para 1-->
+<p><!--para 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:<sup><a href="#note13"><b>13)</b></a></sup>
<ul>
specifying a short identifier of 0000FFFF or less is considered 6 characters, each
-<!--page 33 indent 4-->
+<!--page 33 -->
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)<sup><a href="#note14"><b>14)</b></a></sup>
</small>
<a name="5.2.4.2" href="#5.2.4.2"><h5>5.2.4.2 Numerical limits</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An implementation is required to document all the limits specified in this subclause,
which are specified in the headers <a href="#7.10"><limits.h></a> and <a href="#7.7"><float.h></a>. Additional limits are
specified in <a href="#7.18"><stdint.h></a>.
<p><b> Forward references</b>: integer types <a href="#7.18"><stdint.h></a> (<a href="#7.18">7.18</a>).
<a name="5.2.4.2.1" href="#5.2.4.2.1"><h5>5.2.4.2.1 Sizes of integer types <limits.h></h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The values given below shall be replaced by constant expressions suitable for use in #if
preprocessing directives. Moreover, except for CHAR_BIT and MB_LEN_MAX, the
following shall be replaced by expressions that have the same type as would an
promotions. Their implementation-defined values shall be equal or greater in magnitude
-<!--page 34 indent 0-->
+<!--page 34 -->
(absolute value) to those shown, with the same sign.
<ul>
<li> number of bits for smallest object that is not a bit-field (byte)
LONG_MAX +2147483647 // 231 - 1
<li> maximum value for an object of type unsigned long int
ULONG_MAX 4294967295 // 232 - 1
-<!--page 35 indent 4-->
+<!--page 35 -->
<li> minimum value for an object of type long long int
LLONG_MIN -9223372036854775807 // -(263 - 1)
<li> maximum value for an object of type long long int
<li> maximum value for an object of type unsigned long long int
ULLONG_MAX 18446744073709551615 // 264 - 1
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
If the value of an object of type char is treated as a signed integer when used in an
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
</small>
<a name="5.2.4.2.2" href="#5.2.4.2.2"><h5>5.2.4.2.2 Characteristics of floating types <float.h></h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The characteristics of floating types are defined in terms of a model that describes a
representation of floating-point numbers and values that provide information about an
implementation's floating-point arithmetic.<sup><a href="#note16"><b>16)</b></a></sup> The following parameters are used to
define the model for each floating-point type:
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
s sign ((+-)1)
b base or radix of exponent representation (an integer > 1)
k=1
emin <= e <= emax</pre>
-<p><!--para 3-->
+<p><!--para 3 -->
In addition to normalized floating-point numbers ( f 1 > 0 if x != 0), floating types may be
able to contain other kinds of floating-point numbers, such as subnormal floating-point
numbers (x != 0, e = emin , f 1 = 0) and unnormalized floating-point numbers (x != 0,
signaling NaN generally raises a floating-point exception when occurring as an
-<!--page 36 indent 4-->
+<!--page 36 -->
arithmetic operand.<sup><a href="#note17"><b>17)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 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
any requirement to set the sign shall be ignored.
-<p><!--para 5-->
+<p><!--para 5 -->
The accuracy of the floating-point operations (+, -, *, /) and of the library functions in
<a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> that return floating-point results is implementation-
defined, as is the accuracy of the conversion between floating-point internal
representations and string representations performed by the library functions in
<a href="#7.19"><stdio.h></a>, <a href="#7.20"><stdlib.h></a>, and <a href="#7.24"><wchar.h></a>. The implementation may state that the
accuracy is unknown.
-<p><!--para 6-->
+<p><!--para 6 -->
All integer values in the <a href="#7.7"><float.h></a> header, except FLT_ROUNDS, shall be constant
expressions suitable for use in #if preprocessing directives; all floating values shall be
constant expressions. All except DECIMAL_DIG, FLT_EVAL_METHOD, FLT_RADIX,
and FLT_ROUNDS have separate names for all three floating-point types. The floating-
point model representation is provided for all values except FLT_EVAL_METHOD and
FLT_ROUNDS.
-<p><!--para 7-->
+<p><!--para 7 -->
The rounding mode for floating-point addition is characterized by the implementation-
defined value of FLT_ROUNDS:<sup><a href="#note18"><b>18)</b></a></sup>
<pre>
3 toward negative infinity</pre>
All other values for FLT_ROUNDS characterize implementation-defined rounding
behavior.
-<p><!--para 8-->
+<p><!--para 8 -->
Except for assignment and cast (which remove all extra range and precision), the values
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
-<!--page 37 indent 4-->
+<!--page 37 -->
<pre>
-1 indeterminable;
0 evaluate all operations and constants just to the range and precision of the
long double type.</pre>
All other negative values for FLT_EVAL_METHOD characterize implementation-defined
behavior.
-<p><!--para 9-->
+<p><!--para 9 -->
The values given in the following list shall be replaced by constant expressions with
implementation-defined values that are greater or equal in magnitude (absolute value) to
those shown, with the same sign:
-<!--page 38 indent 5-->
+<!--page 38 -->
<pre>
??? p log10 b if b is a power of 10
???
DBL_MAX_10_EXP +37
LDBL_MAX_10_EXP +37
</ul>
-<p><!--para 10-->
+<p><!--para 10 -->
The values given in the following list shall be replaced by constant expressions with
implementation-defined values that are greater than or equal to those shown:
<ul>
DBL_MAX 1E+37
LDBL_MAX 1E+37
</ul>
-<p><!--para 11-->
+<p><!--para 11 -->
The values given in the following list shall be replaced by constant expressions with
implementation-defined (positive) values that are less than or equal to those shown:
<ul>
<li> the difference between 1 and the least value greater than 1 that is representable in the
given floating point type, b1- p
-<!--page 39 indent 5-->
+<!--page 39 -->
FLT_EPSILON 1E-5
DBL_EPSILON 1E-9
LDBL_EPSILON 1E-9
LDBL_MIN 1E-37
</ul>
Recommended practice
-<p><!--para 12-->
+<p><!--para 12 -->
Conversion from (at least) double to decimal with DECIMAL_DIG digits and back
should be the identity function.
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 1 The following describes an artificial floating-point representation that meets the minimum
requirements of this International Standard, and the appropriate values in a <a href="#7.7"><float.h></a> header for type
float:
FLT_MAX 3.40282347E+38F
FLT_MAX_10_EXP +38</pre>
-<p><!--para 14-->
+<p><!--para 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,<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:
FLT_EPSILON 0X1P-23F // hex constant</pre>
-<!--page 40 indent 0-->
+<!--page 40 -->
<pre>
FLT_DIG 6
FLT_MIN_EXP -125
<a href="#7.3"><complex.h></a> (<a href="#7.3">7.3</a>), extended multibyte and wide character utilities <a href="#7.24"><wchar.h></a>
(<a href="#7.24">7.24</a>), floating-point environment <a href="#7.6"><fenv.h></a> (<a href="#7.6">7.6</a>), general utilities <a href="#7.20"><stdlib.h></a>
(<a href="#7.20">7.20</a>), input/output <a href="#7.19"><stdio.h></a> (<a href="#7.19">7.19</a>), mathematics <a href="#7.12"><math.h></a> (<a href="#7.12">7.12</a>).
-<!--page 41 indent 4-->
+<!--page 41 -->
<h6>footnotes</h6>
<p><small><a name="note16" href="#note16">16)</a> The floating-point model is intended to clarify the description of each floating-point characteristic and
<a name="6" href="#6"><h2>6. Language</h2></a>
<a name="6.1" href="#6.1"><h3>6.1 Notation</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In the syntax notation used in this clause, syntactic categories (nonterminals) are
indicated by italic type, and literal words and character set members (terminals) by bold
type. A colon (:) following a nonterminal introduces its definition. Alternative
<pre>
{ expressionopt }</pre>
indicates an optional expression enclosed in braces.
-<p><!--para 2-->
+<p><!--para 2 -->
When syntactic categories are referred to in the main text, they are not italicized and
words are separated by spaces instead of hyphens.
-<p><!--para 3-->
+<p><!--para 3 -->
A summary of the language syntax is given in <a href="#A">annex A</a>.
<a name="6.2" href="#6.2"><h3>6.2 Concepts</h3></a>
<a name="6.2.1" href="#6.2.1"><h4>6.2.1 Scopes of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An identifier can denote an object; a function; a tag or a member of a structure, union, or
enumeration; a typedef name; a label name; a macro name; or a macro parameter. The
same identifier can denote different entities at different points in the program. A member
parameters are not considered further here, because prior to the semantic phase of
program translation any occurrences of macro names in the source file are replaced by the
preprocessing token sequences that constitute their macro definitions.
-<p><!--para 2-->
+<p><!--para 2 -->
For each different entity that an identifier designates, the identifier is visible (i.e., can be
used) only within a region of program text called its scope. Different entities designated
by the same identifier either have different scopes, or are in different name spaces. There
are four kinds of scopes: function, file, block, and function prototype. (A function
prototype is a declaration of a function that declares the types of its parameters.)
-<p><!--para 3-->
+<p><!--para 3 -->
A label name is the only kind of identifier that has function scope. It can be used (in a
goto statement) anywhere in the function in which it appears, and is declared implicitly
by its syntactic appearance (followed by a : and a statement).
-<p><!--para 4-->
+<p><!--para 4 -->
Every other identifier has scope determined by the placement of its declaration (in a
declarator or type specifier). If the declarator or type specifier that declares the identifier
appears outside of any block or list of parameters, the identifier has file scope, which
declares the identifier appears inside a block or within the list of parameter declarations in
a function definition, the identifier has block scope, which terminates at the end of the
associated block. If the declarator or type specifier that declares the identifier appears
-<!--page 42 indent 4-->
+<!--page 42 -->
within the list of parameter declarations in a function prototype (not part of a function
definition), the identifier has function prototype scope, which terminates at the end of the
function declarator. If an identifier designates two different entities in the same name
strict subset of the scope of the other entity (the outer scope). Within the inner scope, the
identifier designates the entity declared in the inner scope; the entity declared in the outer
scope is hidden (and not visible) within the inner scope.
-<p><!--para 5-->
+<p><!--para 5 -->
Unless explicitly stated otherwise, where this International Standard uses the term
''identifier'' to refer to some entity (as opposed to the syntactic construct), it refers to the
entity in the relevant name space whose declaration is visible at the point the identifier
occurs.
-<p><!--para 6-->
+<p><!--para 6 -->
Two identifiers have the same scope if and only if their scopes terminate at the same
point.
-<p><!--para 7-->
+<p><!--para 7 -->
Structure, union, and enumeration tags have scope that begins just after the appearance of
the tag in a type specifier that declares the tag. Each enumeration constant has scope that
begins just after the appearance of its defining enumerator in an enumerator list. Any
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"><h4>6.2.2 Linkages of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 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.<sup><a href="#note21"><b>21)</b></a></sup> There are
three kinds of linkage: external, internal, and none.
-<p><!--para 2-->
+<p><!--para 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
function. Within one translation unit, each declaration of an identifier with internal
linkage denotes the same object or function. Each declaration of an identifier with no
linkage denotes a unique entity.
-<p><!--para 3-->
+<p><!--para 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.<sup><a href="#note22"><b>22)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
For an identifier declared with the storage-class specifier extern in a scope in which a
-<!--page 43 indent 4-->
+<!--page 43 -->
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.
-<p><!--para 5-->
+<p><!--para 5 -->
If the declaration of an identifier for a function has no storage-class specifier, its linkage
is determined exactly as if it were declared with the storage-class specifier extern. If
the declaration of an identifier for an object has file scope and no storage-class specifier,
its linkage is external.
-<p><!--para 6-->
+<p><!--para 6 -->
The following identifiers have no linkage: an identifier declared to be anything other than
an object or a function; an identifier declared to be a function parameter; a block scope
identifier for an object declared without the storage-class specifier extern.
-<p><!--para 7-->
+<p><!--para 7 -->
If, within a translation unit, the same identifier appears with both internal and external
linkage, the behavior is undefined.
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>), expressions (<a href="#6.5">6.5</a>), external definitions (<a href="#6.9">6.9</a>),
</small>
<a name="6.2.3" href="#6.2.3"><h4>6.2.3 Name spaces of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
If more than one declaration of a particular identifier is visible at any point in a
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:
-<!--page 44 indent 4-->
+<!--page 44 -->
<h6>footnotes</h6>
<p><small><a name="note24" href="#note24">24)</a> There is only one name space for tags even though three are possible.
</small>
<a name="6.2.4" href="#6.2.4"><h4>6.2.4 Storage durations of objects</h4></a>
-<p><!--para 1-->
+<p><!--para 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>.
-<p><!--para 2-->
+<p><!--para 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,<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.
-<p><!--para 3-->
+<p><!--para 3 -->
An object whose identifier is declared with external or internal linkage, or with the
storage-class specifier static has static storage duration. Its lifetime is the entire
execution of the program and its stored value is initialized only once, prior to program
startup.
-<p><!--para 4-->
+<p><!--para 4 -->
An object whose identifier is declared with no linkage and without the storage-class
specifier static has automatic storage duration.
-<p><!--para 5-->
+<p><!--para 5 -->
For such an object that does not have a variable length array type, its lifetime extends
from entry into the block with which it is associated until execution of that block ends in
any way. (Entering an enclosed block or calling a function suspends, but does not end,
initialization is specified for the object, it is performed each time the declaration is
reached in the execution of the block; otherwise, the value becomes indeterminate each
time the declaration is reached.
-<p><!--para 6-->
+<p><!--para 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.<sup><a href="#note27"><b>27)</b></a></sup> If the scope is entered recursively, a new instance of the object is created
-<!--page 45 indent 4-->
+<!--page 45 -->
<h6>footnotes</h6>
<p><small><a name="note25" href="#note25">25)</a> The term ''constant address'' means that two pointers to the object constructed at possibly different
</small>
<a name="6.2.5" href="#6.2.5"><h4>6.2.5 Types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The meaning of a value stored in an object or returned by a function is determined by the
type of the expression used to access it. (An identifier declared to be an object is the
simplest such expression; the type is specified in the declaration of the identifier.) Types
are partitioned into object types (types that fully describe objects), function types (types
that describe functions), and incomplete types (types that describe objects but lack
information needed to determine their sizes).
-<p><!--para 2-->
+<p><!--para 2 -->
An object declared as type _Bool is large enough to store the values 0 and 1.
-<p><!--para 3-->
+<p><!--para 3 -->
An object declared as type char is large enough to store any member of the basic
execution character set. If a member of the basic execution character set is stored in a
char object, its value is guaranteed to be nonnegative. If any other character is stored in
a char object, the resulting value is implementation-defined but shall be within the range
of values that can be represented in that type.
-<p><!--para 4-->
+<p><!--para 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.<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>
-<p><!--para 5-->
+<p><!--para 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
INT_MIN to INT_MAX as defined in the header <a href="#7.10"><limits.h></a>).
-<p><!--para 6-->
+<p><!--para 6 -->
For each of the signed integer types, there is a corresponding (but different) unsigned
integer type (designated with the keyword unsigned) that uses the same amount of
storage (including sign information) and has the same alignment requirements. The type
-<!--page 46 indent 5-->
-<p><!--para 7-->
+<!--page 46 -->
+<p><!--para 7 -->
The standard signed integer types and standard unsigned integer types are collectively
called the standard integer types, the extended signed integer types and extended
unsigned integer types are collectively called the extended integer types.
-<p><!--para 8-->
+<p><!--para 8 -->
For any two integer types with the same signedness and different integer conversion rank
(see <a href="#6.3.1.1">6.3.1.1</a>), the range of values of the type with smaller integer conversion rank is a
subrange of the values of the other type.
-<p><!--para 9-->
+<p><!--para 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.<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.
-<p><!--para 10-->
+<p><!--para 10 -->
There are three real floating types, designated as float, double, and long
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.
-<p><!--para 11-->
+<p><!--para 11 -->
There are three complex types, designated as float _Complex, double
_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.
-<p><!--para 12-->
+<p><!--para 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
by deleting the keyword _Complex from the type name.
-<p><!--para 13-->
+<p><!--para 13 -->
Each complex type has the same representation and alignment requirements as an array
type containing exactly two elements of the corresponding real type; the first element is
equal to the real part, and the second element to the imaginary part, of the complex
number.
-<p><!--para 14-->
+<p><!--para 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.<sup><a href="#note34"><b>34)</b></a></sup>
-<!--page 47 indent 5-->
-<p><!--para 15-->
+<!--page 47 -->
+<p><!--para 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.<sup><a href="#note35"><b>35)</b></a></sup>
-<p><!--para 16-->
+<p><!--para 16 -->
An enumeration comprises a set of named integer constant values. Each distinct
enumeration constitutes a different enumerated type.
-<p><!--para 17-->
+<p><!--para 17 -->
The type char, the signed and unsigned integer types, and the enumerated types are
collectively called integer types. The integer and real floating types are collectively called
real types.
-<p><!--para 18-->
+<p><!--para 18 -->
Integer and floating types are collectively called arithmetic types. Each arithmetic type
belongs to one type domain: the real type domain comprises the real types, the complex
type domain comprises the complex types.
-<p><!--para 19-->
+<p><!--para 19 -->
The void type comprises an empty set of values; it is an incomplete type that cannot be
completed.
-<p><!--para 20-->
+<p><!--para 20 -->
Any number of derived types can be constructed from the object, function, and
incomplete types, as follows:
<ul>
-<!--page 48 indent 5-->
+<!--page 48 -->
<li> A pointer type may be derived from a function type, an object type, or an incomplete
type, called the referenced type. A pointer type describes an object whose value
provides a reference to an entity of the referenced type. A pointer type derived from
pointer type from a referenced type is called ''pointer type derivation''.
</ul>
These methods of constructing derived types can be applied recursively.
-<p><!--para 21-->
+<p><!--para 21 -->
Arithmetic types and pointer types are collectively called scalar types. Array and
structure types are collectively called aggregate types.<sup><a href="#note37"><b>37)</b></a></sup>
-<p><!--para 22-->
+<p><!--para 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
type. It is completed, for all declarations of that type, by declaring the same structure or
union tag with its defining content later in the same scope.
-<p><!--para 23-->
+<p><!--para 23 -->
A type has known constant size if the type is not incomplete and is not a variable length
array type.
-<p><!--para 24-->
+<p><!--para 24 -->
Array, function, and pointer types are collectively called derived declarator types. A
declarator type derivation from a type T is the construction of a derived declarator type
from T by the application of an array-type, a function-type, or a pointer-type derivation to
T.
-<p><!--para 25-->
+<p><!--para 25 -->
A type is characterized by its type category, which is either the outermost derivation of a
derived type (as noted above in the construction of derived types), or the type itself if the
type consists of no derived types.
-<p><!--para 26-->
+<p><!--para 26 -->
Any type so far mentioned is an unqualified type. Each unqualified type has several
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.<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.
-<p><!--para 27-->
+<p><!--para 27 -->
A pointer to void shall have the same representation and alignment requirements as a
pointer to a character type.39) Similarly, pointers to qualified or unqualified versions of
compatible types shall have the same representation and alignment requirements. All
-<!--page 49 indent 5-->
+<!--page 49 -->
pointers to structure types shall have the same representation and alignment requirements
as each other. All pointers to union types shall have the same representation and
alignment requirements as each other. Pointers to other types need not have the same
representation or alignment requirements.
-<p><!--para 28-->
+<p><!--para 28 -->
EXAMPLE 1 The type designated as ''float *'' has type ''pointer to float''. Its type category is
pointer, not a floating type. The const-qualified version of this type is designated as ''float * const''
whereas the type designated as ''const float *'' is not a qualified type -- its type is ''pointer to const-
qualified float'' and is a pointer to a qualified type.
-<p><!--para 29-->
+<p><!--para 29 -->
EXAMPLE 2 The type designated as ''struct tag (*[5])(float)'' has type ''array of pointer to
function returning struct tag''. The array has length five and the function has a single parameter of type
float. Its type category is array.
<a name="6.2.6" href="#6.2.6"><h4>6.2.6 Representations of types</h4></a>
<a name="6.2.6.1" href="#6.2.6.1"><h5>6.2.6.1 General</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The representations of all types are unspecified except as stated in this subclause.
-<p><!--para 2-->
+<p><!--para 2 -->
Except for bit-fields, objects are composed of contiguous sequences of one or more bytes,
the number, order, and encoding of which are either explicitly specified or
implementation-defined.
-<p><!--para 3-->
+<p><!--para 3 -->
Values stored in unsigned bit-fields and objects of type unsigned char shall be
represented using a pure binary notation.<sup><a href="#note40"><b>40)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 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
bits the bit-field comprises in the addressable storage unit holding it. Two values (other
than NaNs) with the same object representation compare equal, but values that compare
equal may have different object representations.
-<p><!--para 5-->
+<p><!--para 5 -->
Certain object representations need not represent a value of the object type. If the stored
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.<sup><a href="#note41"><b>41)</b></a></sup> Such a representation is called
-<!--page 50 indent 4-->
+<!--page 50 -->
a trap representation.
-<p><!--para 6-->
+<p><!--para 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.<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.
-<p><!--para 7-->
+<p><!--para 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.
-<p><!--para 8-->
+<p><!--para 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.<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
</small>
<a name="6.2.6.2" href="#6.2.6.2"><h5>6.2.6.2 Integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
For unsigned integer types other than unsigned char, the bits of the object
representation shall be divided into two groups: value bits and padding bits (there need
not be any of the latter). If there are N value bits, each bit shall represent a different
power of 2 between 1 and 2 N -1 , so that objects of that type shall be capable of
representing values from 0 to 2 N - 1 using a pure binary representation; this shall be
known as the value representation. The values of any padding bits are unspecified.<sup><a href="#note44"><b>44)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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;
-<!--page 51 indent 4-->
+<!--page 51 -->
there shall be exactly one sign bit. Each bit that is a value bit shall have the same value as
the same bit in the object representation of the corresponding unsigned type (if there are
M value bits in the signed type and N in the unsigned type, then M <= N ). If the sign bit
complement), is a trap representation or a normal value. In the case of sign and
magnitude and ones' complement, if this representation is a normal value it is called a
negative zero.
-<p><!--para 3-->
+<p><!--para 3 -->
If the implementation supports negative zeros, they shall be generated only by:
<ul>
<li> the &, |, ^, ~, <<, and >> operators with arguments that produce such a value;
</ul>
It is unspecified whether these cases actually generate a negative zero or a normal zero,
and whether a negative zero becomes a normal zero when stored in an object.
-<p><!--para 4-->
+<p><!--para 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.
-<p><!--para 5-->
+<p><!--para 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
zero in that type.
-<p><!--para 6-->
+<p><!--para 6 -->
The precision of an integer type is the number of bits it uses to represent values,
excluding any sign and padding bits. The width of an integer type is the same but
including any sign bit; thus for unsigned integer types the two values are the same, while
-<!--page 52 indent 4-->
+<!--page 52 -->
for signed integer types the width is one greater than the precision.
<h6>footnotes</h6>
</small>
<a name="6.2.7" href="#6.2.7"><h4>6.2.7 Compatible type and composite type</h4></a>
-<p><!--para 1-->
+<p><!--para 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.<sup><a href="#note46"><b>46)</b></a></sup> Moreover, two structure,
members shall be declared in the same order. For two structures or unions, corresponding
bit-fields shall have the same widths. For two enumerations, corresponding members
shall have the same values.
-<p><!--para 2-->
+<p><!--para 2 -->
All declarations that refer to the same object or function shall have compatible type;
otherwise, the behavior is undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
A composite type can be constructed from two types that are compatible; it is a type that
is compatible with both of the two types and satisfies the following conditions:
<ul>
parameters.
</ul>
These rules apply recursively to the types from which the two types are derived.
-<p><!--para 4-->
+<p><!--para 4 -->
For an identifier with internal or external linkage declared in a scope in which a prior
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
-<!--page 53 indent 4-->
-<p><!--para 5-->
+<!--page 53 -->
+<p><!--para 5 -->
EXAMPLE Given the following two file scope declarations:
<pre>
int f(int (*)(), double (*)[3]);
int f(int (*)(char *), double (*)[]);</pre>
The resulting composite type for the function is:
-<!--page 54 indent 4-->
+<!--page 54 -->
<pre>
int f(int (*)(char *), double (*)[3]);</pre>
</small>
<a name="6.3" href="#6.3"><h3>6.3 Conversions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Several operators convert operand values from one type to another automatically. This
subclause specifies the result required from such an implicit conversion, as well as those
that result from a cast operation (an explicit conversion). The list in <a href="#6.3.1.8">6.3.1.8</a> summarizes
the conversions performed by most ordinary operators; it is supplemented as required by
the discussion of each operator in <a href="#6.5">6.5</a>.
-<p><!--para 2-->
+<p><!--para 2 -->
Conversion of an operand value to a compatible type causes no change to the value or the
representation.
<p><b> Forward references</b>: cast operators (<a href="#6.5.4">6.5.4</a>).
<a name="6.3.1" href="#6.3.1"><h4>6.3.1 Arithmetic operands</h4></a>
<a name="6.3.1.1" href="#6.3.1.1"><h5>6.3.1.1 Boolean, characters, and integers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Every integer type has an integer conversion rank defined as follows:
<ul>
<li> No two signed integer types shall have the same rank, even if they have the same
<li> For all integer types T1, T2, and T3, if T1 has greater rank than T2 and T2 has
greater rank than T3, then T1 has greater rank than T3.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The following may be used in an expression wherever an int or unsigned int may
be used:
-<!--page 55 indent 4-->
+<!--page 55 -->
<ul>
<li> An object or expression with an integer type whose integer conversion rank is less
than or equal to the rank of int and 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.<sup><a href="#note48"><b>48)</b></a></sup> All other types are unchanged by the integer promotions.
-<p><!--para 3-->
+<p><!--para 3 -->
The integer promotions preserve value including sign. As discussed earlier, whether a
''plain'' char is treated as signed is implementation-defined.
<p><b> Forward references</b>: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>), structure and union specifiers
</small>
<a name="6.3.1.2" href="#6.3.1.2"><h5>6.3.1.2 Boolean type</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When any scalar value is converted to _Bool, the result is 0 if the value compares equal
to 0; otherwise, the result is 1.
<a name="6.3.1.3" href="#6.3.1.3"><h5>6.3.1.3 Signed and unsigned integers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value with integer type is converted to another integer type other than _Bool, if
the value can be represented by the new type, it is unchanged.
-<p><!--para 2-->
+<p><!--para 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.<sup><a href="#note49"><b>49)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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.
</small>
<a name="6.3.1.4" href="#6.3.1.4"><h5>6.3.1.4 Real floating and integer</h5></a>
-<p><!--para 1-->
+<p><!--para 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.<sup><a href="#note50"><b>50)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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
-<!--page 56 indent 4-->
+<!--page 56 -->
exactly, the result is either the nearest higher or nearest lower representable value, chosen
in an implementation-defined manner. If the value being converted is outside the range of
values that can be represented, the behavior is undefined.
</small>
<a name="6.3.1.5" href="#6.3.1.5"><h5>6.3.1.5 Real floating types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a float is promoted to double or long double, or a double is promoted
to long double, its value is unchanged (if the source value is represented in the
precision and range of its type).
-<p><!--para 2-->
+<p><!--para 2 -->
When a double is demoted to float, a long double is demoted to double or
float, or a value being represented in greater precision and range than required by its
semantic type (see <a href="#6.3.1.8">6.3.1.8</a>) is explicitly converted (including to its own type), if the value
outside the range of values that can be represented, the behavior is undefined.
<a name="6.3.1.6" href="#6.3.1.6"><h5>6.3.1.6 Complex types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value of complex type is converted to another complex type, both the real and
imaginary parts follow the conversion rules for the corresponding real types.
<a name="6.3.1.7" href="#6.3.1.7"><h5>6.3.1.7 Real and complex</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value of real type is converted to a complex type, the real part of the complex
result value is determined by the rules of conversion to the corresponding real type and
the imaginary part of the complex result value is a positive zero or an unsigned zero.
-<p><!--para 2-->
+<p><!--para 2 -->
When a value of complex type is converted to a real type, the imaginary part of the
complex value is discarded and the value of the real part is converted according to the
conversion rules for the corresponding real type.
<a name="6.3.1.8" href="#6.3.1.8"><h5>6.3.1.8 Usual arithmetic conversions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Many operators that expect operands of arithmetic type cause conversions and yield result
types in a similar way. The purpose is to determine a common real type for the operands
and result. For the specified operands, each operand is converted, without change of type
explicitly stated otherwise, the common real type is also the corresponding real type of
the result, whose type domain is the type domain of the operands if they are the same,
and complex otherwise. This pattern is called the usual arithmetic conversions:
-<!--page 57 indent 4-->
-<p><!--para 2-->
+<!--page 57 -->
+<p><!--para 2 -->
<pre>
First, if the corresponding real type of either operand is long double, the other
operand is converted, without change of type domain, to a type whose
-<!--page 58 indent 4-->
+<!--page 58 -->
<h6>footnotes</h6>
<p><small><a name="note51" href="#note51">51)</a> For example, addition of a double _Complex and a float entails just the conversion of the
<a name="6.3.2" href="#6.3.2"><h4>6.3.2 Other operands</h4></a>
<a name="6.3.2.1" href="#6.3.2.1"><h5>6.3.2.1 Lvalues, arrays, and function designators</h5></a>
-<p><!--para 1-->
+<p><!--para 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
not have an incomplete type, does not have a const-qualified type, and if it is a structure
or union, does not have any member (including, recursively, any member or element of
all contained aggregates or unions) with a const-qualified type.
-<p><!--para 2-->
+<p><!--para 2 -->
Except when it is the operand of the sizeof operator, the unary & operator, the ++
operator, the -- operator, or the left operand of the . operator or an assignment operator,
an lvalue that does not have array type is converted to the value stored in the designated
unqualified version of the type of the lvalue; otherwise, the value has the type of the
lvalue. If the lvalue has an incomplete type and does not have array type, the behavior is
undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
Except when it is the operand of the sizeof operator or the unary & operator, or is a
string literal used to initialize an array, an expression that has type ''array of type'' is
converted to an expression with type ''pointer to type'' that points to the initial element of
the array object and is not an lvalue. If the array object has register storage class, the
behavior is undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
A function designator is an expression that has function type. Except when it is the
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
(<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>).
-<!--page 59 indent 4-->
+<!--page 59 -->
<h6>footnotes</h6>
<p><small><a name="note53" href="#note53">53)</a> The name ''lvalue'' comes originally from the assignment expression E1 = E2, in which the left
</small>
<a name="6.3.2.2" href="#6.3.2.2"><h5>6.3.2.2 void</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The (nonexistent) value of a void expression (an expression that has type void) shall not
be used in any way, and implicit or explicit conversions (except to void) shall not be
applied to such an expression. If an expression of any other type is evaluated as a void
side effects.)
<a name="6.3.2.3" href="#6.3.2.3"><h5>6.3.2.3 Pointers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A pointer to void may be converted to or from a pointer to any incomplete or object
type. A pointer to any incomplete or object type may be converted to a pointer to void
and back again; the result shall compare equal to the original pointer.
-<p><!--para 2-->
+<p><!--para 2 -->
For any qualifier q, a pointer to a non-q-qualified type may be converted to a pointer to
the q-qualified version of the type; the values stored in the original and converted pointers
shall compare equal.
-<p><!--para 3-->
+<p><!--para 3 -->
An integer constant expression with the value 0, or such an expression cast to type
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.
-<p><!--para 4-->
+<p><!--para 4 -->
Conversion of a null pointer to another pointer type yields a null pointer of that type.
Any two null pointers shall compare equal.
-<p><!--para 5-->
+<p><!--para 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.<sup><a href="#note56"><b>56)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 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.
-<p><!--para 7-->
+<p><!--para 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 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
-<!--page 60 indent 4-->
+<!--page 60 -->
converted to a pointer to a character type, the result points to the lowest addressed byte of
the object. Successive increments of the result, up to the size of the object, yield pointers
to the remaining bytes of the object.
-<p><!--para 8-->
+<p><!--para 8 -->
A pointer to a function of one type may be converted to a pointer to a function of another
type and back again; the result shall compare equal to the original pointer. If a converted
pointer is used to call a function whose type is not compatible with the pointed-to type,
the behavior is undefined.
<p><b> Forward references</b>: cast operators (<a href="#6.5.4">6.5.4</a>), equality operators (<a href="#6.5.9">6.5.9</a>), integer types
capable of holding object pointers (<a href="#7.18.1.4">7.18.1.4</a>), simple assignment (<a href="#6.5.16.1">6.5.16.1</a>).
-<!--page 61 indent 4-->
+<!--page 61 -->
<h6>footnotes</h6>
<p><small><a name="note55" href="#note55">55)</a> The macro NULL is defined in <a href="#7.17"><stddef.h></a> (and other headers) as a null pointer constant; see <a href="#7.17">7.17</a>.
<a name="6.4" href="#6.4"><h3>6.4 Lexical elements</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
token:
keyword
punctuator
each non-white-space character that cannot be one of the above</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each preprocessing token that is converted to a token shall have the lexical form of a
keyword, an identifier, a constant, a string literal, or a punctuator.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A token is the minimal lexical element of the language in translation phases 7 and 8. The
categories of tokens are: keywords, identifiers, constants, string literals, and punctuators.
A preprocessing token is the minimal lexical element of the language in translation
-<!--page 62 indent 4-->
-<p><!--para 4-->
+<!--page 62 -->
+<p><!--para 4 -->
If the input stream has been parsed into preprocessing tokens up to a given character, the
next preprocessing token is the longest sequence of characters that could constitute a
preprocessing token. There is one exception to this rule: header name preprocessing
implementation-defined locations within #pragma directives. In such contexts, a
sequence of characters that could be either a header name or a string literal is recognized
as the former.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 1 The program fragment 1Ex is parsed as a preprocessing number token (one that is not a
valid floating or integer constant token), even though a parse as the pair of preprocessing tokens 1 and Ex
might produce a valid expression (for example, if Ex were a macro defined as +1). Similarly, the program
fragment 1E1 is parsed as a preprocessing number (one that is a valid floating constant token), whether or
not E is a macro name.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 2 The program fragment x+++++y is parsed as x ++ ++ + y, which violates a constraint on
increment operators, even though the parse x ++ + ++ y might yield a correct expression.
<a name="6.4.1" href="#6.4.1"><h4>6.4.1 Keywords</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
keyword: one of
auto enum restrict unsigned
double long typedef
else register union</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The above tokens (case sensitive) are reserved (in translation phases 7 and 8) for use as
keywords, and shall not be used otherwise. The keyword _Imaginary is reserved for
specifying imaginary types.<sup><a href="#note59"><b>59)</b></a></sup>
-<!--page 63 indent 4-->
+<!--page 63 -->
<h6>footnotes</h6>
<p><small><a name="note59" href="#note59">59)</a> One possible specification for imaginary types appears in <a href="#G">annex G</a>.
<a name="6.4.2.1" href="#6.4.2.1"><h5>6.4.2.1 General</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
identifier:
identifier-nondigit
digit: one of
0 1 2 3 4 5 6 7 8 9</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier is a sequence of nondigit characters (including the underscore _, the
lowercase and uppercase Latin letters, and other characters) and digits, which designates
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.
-<p><!--para 3-->
+<p><!--para 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>.<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
names is implementation-defined.
-<p><!--para 4-->
+<p><!--para 4 -->
When preprocessing tokens are converted to tokens during translation phase 7, if a
preprocessing token could be converted to either a keyword or an identifier, it is converted
to a keyword.
-<!--page 64 indent 4-->
+<!--page 64 -->
Implementation limits
-<p><!--para 5-->
+<p><!--para 5 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, an implementation may limit the number of significant initial
characters in an identifier; the limit for an external name (an identifier that has external
linkage) may be more restrictive than that for an internal name (a macro name or an
identifier that does not have external linkage). The number of significant characters in an
identifier is implementation-defined.
-<p><!--para 6-->
+<p><!--para 6 -->
Any identifiers that differ in a significant character are different identifiers. If two
identifiers differ only in nonsignificant characters, the behavior is undefined.
<p><b> Forward references</b>: universal character names (<a href="#6.4.3">6.4.3</a>), macro replacement (<a href="#6.10.3">6.10.3</a>).
<a name="6.4.2.2" href="#6.4.2.2"><h5>6.4.2.2 Predefined identifiers</h5></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The identifier __func__ shall be implicitly declared by the translator as if,
immediately following the opening brace of each function definition, the declaration
<pre>
static const char __func__[] = "function-name";</pre>
appeared, where function-name is the name of the lexically-enclosing function.<sup><a href="#note61"><b>61)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE Consider the code fragment:
<pre>
#include <a href="#7.19"><stdio.h></a>
-<!--page 65 indent 4-->
+<!--page 65 -->
<h6>footnotes</h6>
<p><small><a name="note61" href="#note61">61)</a> Since the name __func__ is reserved for any use by the implementation (<a href="#7.1.3">7.1.3</a>), if any other
<a name="6.4.3" href="#6.4.3"><h4>6.4.3 Universal character names</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
universal-character-name:
\u hex-quad
hexadecimal-digit hexadecimal-digit
hexadecimal-digit hexadecimal-digit</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A universal character name shall not specify a character whose short identifier is less than
00A0 other than 0024 ($), 0040 (@), or 0060 ('), nor one in the range D800 through
DFFF inclusive.<sup><a href="#note62"><b>62)</b></a></sup>
<h6>Description</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Universal character names may be used in identifiers, character constants, and string
literals to designate characters that are not in the basic character set.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The universal character name \Unnnnnnnn designates the character whose eight-digit
short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.<sup><a href="#note63"><b>63)</b></a></sup> Similarly, the universal
character name \unnnn designates the character whose four-digit short identifier is nnnn
-<!--page 66 indent 4-->
+<!--page 66 -->
<h6>footnotes</h6>
<p><small><a name="note62" href="#note62">62)</a> The disallowed characters are the characters in the basic character set and the code positions reserved
<a name="6.4.4" href="#6.4.4"><h4>6.4.4 Constants</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
constant:
integer-constant
enumeration-constant
character-constant</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each constant shall have a type and the value of a constant shall be in the range of
representable values for its type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Each constant has a type, determined by its form and value, as detailed later.
<a name="6.4.4.1" href="#6.4.4.1"><h5>6.4.4.1 Integer constants</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 67 indent 4-->
+<p><!--para 1 -->
+<!--page 67 -->
<pre>
integer-constant:
decimal-constant integer-suffixopt
long-long-suffix: one of
ll LL</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An integer constant begins with a digit, but has no period or exponent part. It may have a
prefix that specifies its base and a suffix that specifies its type.
-<p><!--para 3-->
+<p><!--para 3 -->
A decimal constant begins with a nonzero digit and consists of a sequence of decimal
digits. An octal constant consists of the prefix 0 optionally followed by a sequence of the
digits 0 through 7 only. A hexadecimal constant consists of the prefix 0x or 0X followed
by a sequence of the decimal digits and the letters a (or A) through f (or F) with values
10 through 15 respectively.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The value of a decimal constant is computed base 10; that of an octal constant, base 8;
that of a hexadecimal constant, base 16. The lexically first digit is the most significant.
-<p><!--para 5-->
+<p><!--para 5 -->
The type of an integer constant is the first of the corresponding list in which its value can
be represented.
-<!--page 68 indent 4-->
+<!--page 68 -->
<pre>
Octal or Hexadecimal</pre>
Suffix Decimal Constant Constant
Both u or U unsigned long long int unsigned long long int
and ll or LL
-<p><!--para 6-->
+<p><!--para 6 -->
If an integer constant cannot be represented by any type in its list, it may have an
extended integer type, if the extended integer type can represent its value. If all of the
types in the list for the constant are signed, the extended integer type shall be signed. If
unsigned. If the list contains both signed and unsigned types, the extended integer type
may be signed or unsigned. If an integer constant cannot be represented by any type in
its list and has no extended integer type, then the integer constant has no type.
-<!--page 69 indent 4-->
+<!--page 69 -->
<a name="6.4.4.2" href="#6.4.4.2"><h5>6.4.4.2 Floating constants</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 70 indent 4-->
+<p><!--para 1 -->
+<!--page 70 -->
<pre>
floating-constant:
decimal-floating-constant
floating-suffix: one of
f l F L</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A floating constant has a significand part that may be followed by an exponent part and a
suffix that specifies its type. The components of the significand part may include a digit
sequence representing the whole-number part, followed by a period (.), followed by a
Either the whole-number part or the fraction part has to be present; for decimal floating
constants, either the period or the exponent part has to be present.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The significand part is interpreted as a (decimal or hexadecimal) rational number; the
digit sequence in the exponent part is interpreted as a decimal integer. For decimal
floating constants, the exponent indicates the power of 10 by which the significand part is
adjacent to the nearest representable value, chosen in an implementation-defined manner.
For hexadecimal floating constants when FLT_RADIX is a power of 2, the result is
correctly rounded.
-<p><!--para 4-->
+<p><!--para 4 -->
An unsuffixed floating constant has type double. If suffixed by the letter f or F, it has
type float. If suffixed by the letter l or L, it has type long double.
-<p><!--para 5-->
+<p><!--para 5 -->
Floating constants are converted to internal format as if at translation-time. The
conversion of a floating constant shall not raise an exceptional condition or a floating-
point exception at execution time.
Recommended practice
-<p><!--para 6-->
+<p><!--para 6 -->
The implementation should produce a diagnostic message if a hexadecimal constant
cannot be represented exactly in its evaluation format; the implementation should then
proceed with the translation of the program.
-<p><!--para 7-->
+<p><!--para 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
-<!--page 71 indent 4-->
+<!--page 71 -->
<h6>footnotes</h6>
<p><small><a name="note64" href="#note64">64)</a> The specification for the library functions recommends more accurate conversion than required for
<a name="6.4.4.3" href="#6.4.4.3"><h5>6.4.4.3 Enumeration constants</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
enumeration-constant:
identifier</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier declared as an enumeration constant has type int.
<p><b> Forward references</b>: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>).
<a name="6.4.4.4" href="#6.4.4.4"><h5>6.4.4.4 Character constants</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 72 indent 4-->
+<p><!--para 1 -->
+<!--page 72 -->
<pre>
character-constant:
' c-char-sequence '
\x hexadecimal-digit
hexadecimal-escape-sequence hexadecimal-digit</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An integer character constant is a sequence of one or more multibyte characters enclosed
in single-quotes, as in 'x'. A wide character constant is the same, except prefixed by the
letter L. With a few exceptions detailed later, the elements of the sequence are any
members of the source character set; they are mapped in an implementation-defined
manner to members of the execution character set.
-<p><!--para 3-->
+<p><!--para 3 -->
The single-quote ', the double-quote ", the question-mark ?, the backslash \, and
arbitrary integer values are representable according to the following table of escape
sequences:
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
single quote ' \'
double quote " \"
The double-quote " and question-mark ? are representable either by themselves or by the
escape sequences \" and \?, respectively, but the single-quote ' and the backslash \
shall be represented, respectively, by the escape sequences \' and \\.
-<p><!--para 5-->
+<p><!--para 5 -->
The octal digits that follow the backslash in an octal escape sequence are taken to be part
of the construction of a single character for an integer character constant or of a single
wide character for a wide character constant. The numerical value of the octal integer so
formed specifies the value of the desired character or wide character.
-<p><!--para 6-->
+<p><!--para 6 -->
The hexadecimal digits that follow the backslash and the letter x in a hexadecimal escape
sequence are taken to be part of the construction of a single character for an integer
character constant or of a single wide character for a wide character constant. The
numerical value of the hexadecimal integer so formed specifies the value of the desired
character or wide character.
-<p><!--para 7-->
+<p><!--para 7 -->
Each octal or hexadecimal escape sequence is the longest sequence of characters that can
constitute the escape sequence.
-<p><!--para 8-->
+<p><!--para 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,
-<!--page 73 indent 5-->
+<!--page 73 -->
<h6>Constraints</h6>
-<p><!--para 9-->
+<p><!--para 9 -->
The value of an octal or hexadecimal escape sequence shall be in the range of
representable values for the type unsigned char for an integer character constant, or
the unsigned type corresponding to wchar_t for a wide character constant.
<h6>Semantics</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
An integer character constant has type int. The value of an integer character constant
containing a single character that maps to a single-byte execution character is the
numerical value of the representation of the mapped character interpreted as an integer.
a single character or escape sequence, its value is the one that results when an object with
type char whose value is that of the single character or escape sequence is converted to
type int.
-<p><!--para 11-->
+<p><!--para 11 -->
A wide character constant has type wchar_t, an integer type defined in the
<a href="#7.17"><stddef.h></a> header. The value of a wide character constant containing a single
multibyte character that maps to a member of the extended execution character set is the
constant containing more than one multibyte character, or containing a multibyte
character or escape sequence not represented in the extended execution character set, is
implementation-defined.
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE 1 The construction '\0' is commonly used to represent the null character.
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 2 Consider implementations that use two's-complement representation for integers and eight
bits for objects that have type char. In an implementation in which type char has the same range of
values as signed char, the integer character constant '\xFF' has the value -1; if type char has the
same range of values as unsigned char, the character constant '\xFF' has the value +255.
-<p><!--para 14-->
+<p><!--para 14 -->
EXAMPLE 3 Even if eight bits are used for objects that have type char, the construction '\x123'
specifies an integer character constant containing only one character, since a hexadecimal escape sequence
is terminated only by a non-hexadecimal character. To specify an integer character constant containing the
escape sequence is terminated after three octal digits. (The value of this two-character integer character
constant is implementation-defined.)
-<p><!--para 15-->
+<p><!--para 15 -->
EXAMPLE 4 Even if 12 or more bits are used for objects that have type wchar_t, the construction
L'\1234' specifies the implementation-defined value that results from the combination of the values
0123 and '4'.
<p><b> Forward references</b>: common definitions <a href="#7.17"><stddef.h></a> (<a href="#7.17">7.17</a>), the mbtowc function
(<a href="#7.20.7.2">7.20.7.2</a>).
-<!--page 74 indent 4-->
+<!--page 74 -->
<h6>footnotes</h6>
<p><small><a name="note65" href="#note65">65)</a> The semantics of these characters were discussed in <a href="#5.2.2">5.2.2</a>. If any other character follows a backslash,
<a name="6.4.5" href="#6.4.5"><h4>6.4.5 String literals</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
string-literal:
" s-char-sequenceopt "
the double-quote ", backslash \, or new-line character
escape-sequence</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A character string literal is a sequence of zero or more multibyte characters enclosed in
double-quotes, as in "xyz". A wide string literal is the same, except prefixed by the
letter L.
-<p><!--para 3-->
+<p><!--para 3 -->
The same considerations apply to each element of the sequence in a character string
literal or a wide string literal as if it were in an integer character constant or a wide
character constant, except that the single-quote ' is representable either by itself or by the
escape sequence \', but the double-quote " shall be represented by the escape sequence
\".
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
In translation phase 6, the multibyte character sequences specified by any sequence of
adjacent character and wide string literal tokens are concatenated into a single multibyte
character sequence. If any of the tokens are wide string literal tokens, the resulting
multibyte character sequence is treated as a wide string literal; otherwise, it is treated as a
character string literal.
-<p><!--para 5-->
+<p><!--para 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.<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
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
-<!--page 75 indent 4-->
+<!--page 75 -->
sequence, as defined by the mbstowcs function with an implementation-defined current
locale. The value of a string literal containing a multibyte character or escape sequence
not represented in the execution character set is implementation-defined.
-<p><!--para 6-->
+<p><!--para 6 -->
It is unspecified whether these arrays are distinct provided their elements have the
appropriate values. If the program attempts to modify such an array, the behavior is
undefined.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE This pair of adjacent character string literals
<pre>
"\x12" "3"</pre>
<a name="6.4.6" href="#6.4.6"><h4>6.4.6 Punctuators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
punctuator: one of
[ ] ( ) { } . ->
, # ##
<: :> <% %> %: %:%:</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A punctuator is a symbol that has independent syntactic and semantic significance.
Depending on context, it may specify an operation to be performed (which in turn may
yield a value or a function designator, produce a side effect, or some combination thereof)
in which case it is known as an operator (other forms of operator also exist in some
contexts). An operand is an entity on which an operator acts.
-<!--page 76 indent 4-->
-<p><!--para 3-->
+<!--page 76 -->
+<p><!--para 3 -->
In all aspects of the language, the six tokens<sup><a href="#note67"><b>67)</b></a></sup>
<pre>
<: :> <% %> %: %:%:</pre>
<a name="6.4.7" href="#6.4.7"><h4>6.4.7 Header names</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
header-name:
< h-char-sequence >
any member of the source character set except
the new-line character and "</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sequences in both forms of header names are mapped in an implementation-defined
manner to headers or external source file names as specified in <a href="#6.10.2">6.10.2</a>.
-<p><!--para 3-->
+<p><!--para 3 -->
If the characters ', \, ", //, or /* occur in the sequence between the < and > delimiters,
the behavior is undefined. Similarly, if the characters ', \, //, or /* occur in the
-<!--page 77 indent 4-->
+<!--page 77 -->
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.<sup><a href="#note70"><b>70)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The following sequence of characters:
<pre>
0x3<1/a.h>1e2
<a name="6.4.8" href="#6.4.8"><h4>6.4.8 Preprocessing numbers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
pp-number:
digit
pp-number P sign
pp-number .</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A preprocessing number begins with a digit optionally preceded by a period (.) and may
be followed by valid identifier characters and the character sequences e+, e-, E+, E-,
p+, p-, P+, or P-.
-<p><!--para 3-->
+<p><!--para 3 -->
Preprocessing number tokens lexically include all floating and integer constant tokens.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
A preprocessing number does not have type or a value; it acquires both after a successful
conversion (as part of translation phase 7) to a floating constant token or an integer
constant token.
-<!--page 78 indent 4-->
+<!--page 78 -->
<a name="6.4.9" href="#6.4.9"><h4>6.4.9 Comments</h4></a>
-<p><!--para 1-->
+<p><!--para 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.<sup><a href="#note71"><b>71)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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
multibyte characters and to find the terminating new-line character.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE
<pre>
"a//b" // four-character string literal
-<!--page 79 indent 4-->
+<!--page 79 -->
<h6>footnotes</h6>
<p><small><a name="note71" href="#note71">71)</a> Thus, /* ... */ comments do not nest.
</small>
<a name="6.5" href="#6.5"><h3>6.5 Expressions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An expression is a sequence of operators and operands that specifies computation of a
value, or that designates an object or a function, or that generates side effects, or that
performs a combination thereof.
-<p><!--para 2-->
+<p><!--para 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.<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>
-<p><!--para 3-->
+<p><!--para 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.
-<p><!--para 4-->
+<p><!--para 4 -->
Some operators (the unary operator ~, and the binary operators <<, >>, &, ^, and |,
collectively described as bitwise operators) are required to have operands that have
integer type. These operators yield values that depend on the internal representations of
integers, and have implementation-defined and undefined aspects for signed types.
-<p><!--para 5-->
+<p><!--para 5 -->
If an exceptional condition occurs during the evaluation of an expression (that is, if the
result is not mathematically defined or not in the range of representable values for its
type), the behavior is undefined.
-<p><!--para 6-->
+<p><!--para 6 -->
The effective type of an object for an access to its stored value is the declared type of the
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
-<!--page 80 indent 4-->
+<!--page 80 -->
effective type of the object for that access and for subsequent accesses that do not modify
the stored value. If a value is copied into an object having no declared type using
memcpy or memmove, or is copied as an array of character type, then the effective type
value is the effective type of the object from which the value is copied, if it has one. For
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.
-<p><!--para 7-->
+<p><!--para 7 -->
An object shall have its stored value accessed only by an lvalue expression that has one of
the following types:<sup><a href="#note76"><b>76)</b></a></sup>
<ul>
members (including, recursively, a member of a subaggregate or contained union), or
<li> a character type.
</ul>
-<p><!--para 8-->
+<p><!--para 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.<sup><a href="#note77"><b>77)</b></a></sup> The FP_CONTRACT pragma in <a href="#7.12"><math.h></a> provides a
-<!--page 81 indent 4-->
+<!--page 81 -->
<h6>footnotes</h6>
<p><small><a name="note72" href="#note72">72)</a> A floating-point status flag is not an object and can be set more than once within an expression.
<a name="6.5.1" href="#6.5.1"><h4>6.5.1 Primary expressions</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
primary-expression:
identifier
string-literal
( expression )</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier is a primary expression, provided it has been declared as designating an
object (in which case it is an lvalue) or a function (in which case it is a function
designator).<sup><a href="#note79"><b>79)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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>.
-<p><!--para 4-->
+<p><!--para 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>.
-<p><!--para 5-->
+<p><!--para 5 -->
A parenthesized expression is a primary expression. Its type and value are identical to
those of the unparenthesized expression. It is an lvalue, a function designator, or a void
expression if the unparenthesized expression is, respectively, an lvalue, a function
<a name="6.5.2" href="#6.5.2"><h4>6.5.2 Postfix operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
postfix-expression:
primary-expression
-<!--page 82 indent 4-->
+<!--page 82 -->
<pre>
argument-expression-list:
assignment-expression
<a name="6.5.2.1" href="#6.5.2.1"><h5>6.5.2.1 Array subscripting</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
One of the expressions shall have type ''pointer to object type'', the other expression shall
have integer type, and the result has type ''type''.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A postfix expression followed by an expression in square brackets [] is a subscripted
designation of an element of an array object. The definition of the subscript operator []
is that E1[E2] is identical to (*((E1)+(E2))). Because of the conversion rules that
apply to the binary + operator, if E1 is an array object (equivalently, a pointer to the
initial element of an array object) and E2 is an integer, E1[E2] designates the E2-th
element of E1 (counting from zero).
-<p><!--para 3-->
+<p><!--para 3 -->
Successive subscript operators designate an element of a multidimensional array object.
If E is an n-dimensional array (n >= 2) with dimensions i x j x . . . x k, then E (used as
other than an lvalue) is converted to a pointer to an (n - 1)-dimensional array with
implicitly as a result of subscripting, the result is the pointed-to (n - 1)-dimensional array,
which itself is converted into a pointer if used as other than an lvalue. It follows from this
that arrays are stored in row-major order (last subscript varies fastest).
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE Consider the array object defined by the declaration
<pre>
int x[3][5];</pre>
<p><b> Forward references</b>: additive operators (<a href="#6.5.6">6.5.6</a>), address and indirection operators
(<a href="#6.5.3.2">6.5.3.2</a>), array declarators (<a href="#6.7.5.2">6.7.5.2</a>).
-<!--page 83 indent 4-->
+<!--page 83 -->
<a name="6.5.2.2" href="#6.5.2.2"><h5>6.5.2.2 Function calls</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The expression that denotes the called function<sup><a href="#note80"><b>80)</b></a></sup> shall have type pointer to function
returning void or returning an object type other than an array type.
-<p><!--para 2-->
+<p><!--para 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
have a type such that its value may be assigned to an object with the unqualified version
of the type of its corresponding parameter.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A postfix expression followed by parentheses () containing a possibly empty, comma-
separated list of expressions is a function call. The postfix expression denotes the called
function. The list of expressions specifies the arguments to the function.
-<p><!--para 4-->
+<p><!--para 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.<sup><a href="#note81"><b>81)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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
an attempt is made to modify the result of a function call or to access it after the next
sequence point, the behavior is undefined.
-<p><!--para 6-->
+<p><!--para 6 -->
If the expression that denotes the called function has a type that does not include a
prototype, the integer promotions are performed on each argument, and arguments that
have type float are promoted to double. These are called the default argument
-<!--page 84 indent 5-->
+<!--page 84 -->
<ul>
<li> one promoted type is a signed integer type, the other promoted type is the
corresponding unsigned integer type, and the value is representable in both types;
<li> both types are pointers to qualified or unqualified versions of a character type or
void.
</ul>
-<p><!--para 7-->
+<p><!--para 7 -->
If the expression that denotes the called function has a type that does include a prototype,
the arguments are implicitly converted, as if by assignment, to the types of the
corresponding parameters, taking the type of each parameter to be the unqualified version
of its declared type. The ellipsis notation in a function prototype declarator causes
argument type conversion to stop after the last declared parameter. The default argument
promotions are performed on trailing arguments.
-<p><!--para 8-->
+<p><!--para 8 -->
No other conversions are performed implicitly; in particular, the number and types of
arguments are not compared with those of the parameters in a function definition that
does not include a function prototype declarator.
-<p><!--para 9-->
+<p><!--para 9 -->
If the function is defined with a type that is not compatible with the type (of the
expression) pointed to by the expression that denotes the called function, the behavior is
undefined.
-<p><!--para 10-->
+<p><!--para 10 -->
The order of evaluation of the function designator, the actual arguments, and
subexpressions within the actual arguments is unspecified, but there is a sequence point
before the actual call.
-<p><!--para 11-->
+<p><!--para 11 -->
Recursive function calls shall be permitted, both directly and indirectly through any chain
of other functions.
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE In the function call
<pre>
(*pf[f1()]) (f2(), f3() + f4())</pre>
<a name="6.5.2.3" href="#6.5.2.3"><h5>6.5.2.3 Structure and union members</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The first operand of the . operator shall have a qualified or unqualified structure or union
type, and the second operand shall name a member of that type.
-<p><!--para 2-->
+<p><!--para 2 -->
The first operand of the -> operator shall have type ''pointer to qualified or unqualified
structure'' or ''pointer to qualified or unqualified union'', and the second operand shall
name a member of the type pointed to.
-<!--page 85 indent 4-->
+<!--page 85 -->
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A postfix expression followed by the . operator and an identifier designates a member of
a structure or union object. The value is that of the named member,<sup><a href="#note82"><b>82)</b></a></sup> and is an lvalue if
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.
-<p><!--para 4-->
+<p><!--para 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.<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.
-<p><!--para 5-->
+<p><!--para 5 -->
One special guarantee is made in order to simplify the use of unions: if a union contains
several structures that share a common initial sequence (see below), and if the union
object currently contains one of these structures, it is permitted to inspect the common
visible. Two structures share a common initial sequence if corresponding members have
compatible types (and, for bit-fields, the same widths) for a sequence of one or more
initial members.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 1 If f is a function returning a structure or union, and x is a member of that structure or
union, f().x is a valid postfix expression but is not an lvalue.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 2 In:
<pre>
struct s { int i; const int ci; };
-<!--page 86 indent 4-->
-<p><!--para 8-->
+<!--page 86 -->
+<p><!--para 8 -->
EXAMPLE 3 The following is a valid fragment:
<pre>
union {
<p><b> Forward references</b>: address and indirection operators (<a href="#6.5.3.2">6.5.3.2</a>), structure and union
specifiers (<a href="#6.7.2.1">6.7.2.1</a>).
-<!--page 87 indent 4-->
+<!--page 87 -->
<h6>footnotes</h6>
<p><small><a name="note82" href="#note82">82)</a> If the member used to access the contents of a union object is not the same as the member last used to
<a name="6.5.2.4" href="#6.5.2.4"><h5>6.5.2.4 Postfix increment and decrement operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The operand of the postfix increment or decrement operator shall have qualified or
unqualified real or pointer type and shall be a modifiable lvalue.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The result of the postfix ++ operator is the value of the operand. After the result is
obtained, the value of the operand is incremented. (That is, the value 1 of the appropriate
type is added to it.) See the discussions of additive operators and compound assignment
for information on constraints, types, and conversions and the effects of operations on
pointers. The side effect of updating the stored value of the operand shall occur between
the previous and the next sequence point.
-<p><!--para 3-->
+<p><!--para 3 -->
The postfix -- operator is analogous to the postfix ++ operator, except that the value of
the operand is decremented (that is, the value 1 of the appropriate type is subtracted from
it).
<a name="6.5.2.5" href="#6.5.2.5"><h5>6.5.2.5 Compound literals</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The type name shall specify an object type or an array of unknown size, but not a variable
length array type.
-<p><!--para 2-->
+<p><!--para 2 -->
No initializer shall attempt to provide a value for an object not contained within the entire
unnamed object specified by the compound literal.
-<p><!--para 3-->
+<p><!--para 3 -->
If the compound literal occurs outside the body of a function, the initializer list shall
consist of constant expressions.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
A postfix expression that consists of a parenthesized type name followed by a brace-
enclosed list of initializers is a compound literal. It provides an unnamed object whose
value is given by the initializer list.<sup><a href="#note84"><b>84)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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.
-<!--page 88 indent 5-->
-<p><!--para 6-->
+<!--page 88 -->
+<p><!--para 6 -->
The value of the compound literal is that of an unnamed object initialized by the
initializer list. If the compound literal occurs outside the body of a function, the object
has static storage duration; otherwise, it has automatic storage duration associated with
the enclosing block.
-<p><!--para 7-->
+<p><!--para 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.<sup><a href="#note85"><b>85)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
String literals, and compound literals with const-qualified types, need not designate
distinct objects.<sup><a href="#note86"><b>86)</b></a></sup>
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 1 The file scope definition
<pre>
int *p = (int []){2, 4};</pre>
second, four. The expressions in this compound literal are required to be constant. The unnamed object
has static storage duration.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 2 In contrast, in
<pre>
void f(void)
pointed to by p and the second, zero. The expressions in this compound literal need not be constant. The
unnamed object has automatic storage duration.
-<p><!--para 11-->
+<p><!--para 11 -->
EXAMPLE 3 Initializers with designations can be combined with compound literals. Structure objects
created using compound literals can be passed to functions without depending on member order:
<pre>
drawline(&(struct point){.x=1, .y=1},
&(struct point){.x=3, .y=4});</pre>
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE 4 A read-only compound literal can be specified through constructions like:
<pre>
(const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}</pre>
-<!--page 89 indent 5-->
-<p><!--para 13-->
+<!--page 89 -->
+<p><!--para 13 -->
EXAMPLE 5 The following three expressions have different meanings:
<pre>
"/tmp/fileXXXXXX"
two have automatic storage duration when they occur within the body of a function, and the first of these
two is modifiable.
-<p><!--para 14-->
+<p><!--para 14 -->
EXAMPLE 6 Like string literals, const-qualified compound literals can be placed into read-only memory
and can even be shared. For example,
<pre>
(const char []){"abc"} == "abc"</pre>
might yield 1 if the literals' storage is shared.
-<p><!--para 15-->
+<p><!--para 15 -->
EXAMPLE 7 Since compound literals are unnamed, a single compound literal cannot specify a circularly
linked object. For example, there is no way to write a self-referential compound literal that could be used
as the function argument in place of the named object endless_zeros below:
struct int_list endless_zeros = {0, &endless_zeros};
eval(endless_zeros);</pre>
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE 8 Each compound literal creates only a single object in a given scope:
<pre>
struct s { int i; };
return p == q && q->i == 1;
}</pre>
The function f() always returns the value 1.
-<p><!--para 17-->
+<p><!--para 17 -->
Note that if an iteration statement were used instead of an explicit goto and a labeled statement, the
lifetime of the unnamed object would be the body of the loop only, and on entry next time around p would
have an indeterminate value, which would result in undefined behavior.
<p><b> Forward references</b>: type names (<a href="#6.7.6">6.7.6</a>), initialization (<a href="#6.7.8">6.7.8</a>).
-<!--page 90 indent 4-->
+<!--page 90 -->
<h6>footnotes</h6>
<p><small><a name="note84" href="#note84">84)</a> Note that this differs from a cast expression. For example, a cast specifies a conversion to scalar types
<a name="6.5.3" href="#6.5.3"><h4>6.5.3 Unary operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
unary-expression:
postfix-expression
<a name="6.5.3.1" href="#6.5.3.1"><h5>6.5.3.1 Prefix increment and decrement operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The operand of the prefix increment or decrement operator shall have qualified or
unqualified real or pointer type and shall be a modifiable lvalue.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The value of the operand of the prefix ++ operator is incremented. The result is the new
value of the operand after incrementation. The expression ++E is equivalent to (E+=1).
See the discussions of additive operators and compound assignment for information on
constraints, types, side effects, and conversions and the effects of operations on pointers.
-<p><!--para 3-->
+<p><!--para 3 -->
The prefix -- operator is analogous to the prefix ++ operator, except that the value of the
operand is decremented.
<p><b> Forward references</b>: additive operators (<a href="#6.5.6">6.5.6</a>), compound assignment (<a href="#6.5.16.2">6.5.16.2</a>).
<a name="6.5.3.2" href="#6.5.3.2"><h5>6.5.3.2 Address and indirection operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The operand of the unary & operator shall be either a function designator, the result of a
[] or unary * operator, or an lvalue that designates an object that is not a bit-field and is
not declared with the register storage-class specifier.
-<p><!--para 2-->
+<p><!--para 2 -->
The operand of the unary * operator shall have pointer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The unary & operator yields the address of its operand. If the operand has type ''type'',
the result has type ''pointer to type''. If the operand is the result of a unary * operator,
neither that operator nor the & operator is evaluated and the result is as if both were
omitted, except that the constraints on the operators still apply and the result is not an
lvalue. Similarly, if the operand is the result of a [] operator, neither the & operator nor
-<!--page 91 indent 4-->
+<!--page 91 -->
the unary * that is implied by the [] is evaluated and the result is as if the & operator
were removed and the [] operator were changed to a + operator. Otherwise, the result is
a pointer to the object or function designated by its operand.
-<p><!--para 4-->
+<p><!--para 4 -->
The unary * operator denotes indirection. If the operand points to a function, the result is
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
<a name="6.5.3.3" href="#6.5.3.3"><h5>6.5.3.3 Unary arithmetic operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The operand of the unary + or - operator shall have arithmetic type; of the ~ operator,
integer type; of the ! operator, scalar type.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The result of the unary + operator is the value of its (promoted) operand. The integer
promotions are performed on the operand, and the result has the promoted type.
-<p><!--para 3-->
+<p><!--para 3 -->
The result of the unary - operator is the negative of its (promoted) operand. The integer
promotions are performed on the operand, and the result has the promoted type.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the ~ operator is the bitwise complement of its (promoted) operand (that is,
each bit in the result is set if and only if the corresponding bit in the converted operand is
not set). The integer promotions are performed on the operand, and the result has the
promoted type. If the promoted type is an unsigned type, the expression ~E is equivalent
to the maximum value representable in that type minus E.
-<p><!--para 5-->
+<p><!--para 5 -->
The result of the logical negation operator ! is 0 if the value of its operand compares
unequal to 0, 1 if the value of its operand compares equal to 0. The result has type int.
The expression !E is equivalent to (0==E).
-<!--page 92 indent 4-->
+<!--page 92 -->
<a name="6.5.3.4" href="#6.5.3.4"><h5>6.5.3.4 The sizeof operator</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The sizeof operator shall not be applied to an expression that has function type or an
incomplete type, to the parenthesized name of such a type, or to an expression that
designates a bit-field member.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sizeof operator yields the size (in bytes) of its operand, which may be an
expression or the parenthesized name of a type. The size is determined from the type of
the operand. The result is an integer. If the type of the operand is a variable length array
type, the operand is evaluated; otherwise, the operand is not evaluated and the result is an
integer constant.
-<p><!--para 3-->
+<p><!--para 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.<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.
-<p><!--para 4-->
+<p><!--para 4 -->
The value of the result is implementation-defined, and its type (an unsigned integer type)
is size_t, defined in <a href="#7.17"><stddef.h></a> (and other headers).
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 1 A principal use of the sizeof operator is in communication with routines such as storage
allocators and I/O systems. A storage-allocation function might accept a size (in bytes) of an object to
allocate and return a pointer to void. For example:
The implementation of the alloc function should ensure that its return value is aligned suitably for
conversion to a pointer to double.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 2 Another use of the sizeof operator is to compute the number of elements in an array:
<pre>
sizeof array / sizeof array[0]</pre>
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 3 In this example, the size of a variable length array is computed and returned from a
function:
<pre>
-<!--page 93 indent 4-->
+<!--page 93 -->
<pre>
int main()
{
<a name="6.5.4" href="#6.5.4"><h4>6.5.4 Cast operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
cast-expression:
unary-expression
( type-name ) cast-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Unless the type name specifies a void type, the type name shall specify qualified or
unqualified scalar type and the operand shall have scalar type.
-<p><!--para 3-->
+<p><!--para 3 -->
Conversions that involve pointers, other than where permitted by the constraints of
<a href="#6.5.16.1">6.5.16.1</a>, shall be specified by means of an explicit cast.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
Preceding an expression by a parenthesized type name converts the value of the
expression to the named type. This construction is called a cast.<sup><a href="#note89"><b>89)</b></a></sup> A cast that specifies
no conversion has no effect on the type or value of an expression.
-<p><!--para 5-->
+<p><!--para 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
type of the expression is the same as the named type.
-<!--page 94 indent 4-->
+<!--page 94 -->
<h6>footnotes</h6>
<p><small><a name="note89" href="#note89">89)</a> A cast does not yield an lvalue. Thus, a cast to a qualified type has the same effect as a cast to the
<a name="6.5.5" href="#6.5.5"><h4>6.5.5 Multiplicative operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
multiplicative-expression:
cast-expression
multiplicative-expression / cast-expression
multiplicative-expression % cast-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have arithmetic type. The operands of the % operator shall
have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the binary * operator is the product of the operands.
-<p><!--para 5-->
+<p><!--para 5 -->
The result of the / operator is the quotient from the division of the first operand by the
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.
-<p><!--para 6-->
+<p><!--para 6 -->
When integers are divided, the result of the / operator is the algebraic quotient with any
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"><h4>6.5.6 Additive operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
additive-expression:
multiplicative-expression
additive-expression + multiplicative-expression
additive-expression - multiplicative-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
For addition, either both operands shall have arithmetic type, or one operand shall be a
pointer to an object type and the other shall have integer type. (Incrementing is
equivalent to adding 1.)
-<p><!--para 3-->
+<p><!--para 3 -->
For subtraction, one of the following shall hold:
<ul>
<li> both operands have arithmetic type;
-<!--page 95 indent 4-->
+<!--page 95 -->
<li> both operands are pointers to qualified or unqualified versions of compatible object
types; or
<li> the left operand is a pointer to an object type and the right operand has integer type.
</ul>
(Decrementing is equivalent to subtracting 1.)
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If both operands have arithmetic type, the usual arithmetic conversions are performed on
them.
-<p><!--para 5-->
+<p><!--para 5 -->
The result of the binary + operator is the sum of the operands.
-<p><!--para 6-->
+<p><!--para 6 -->
The result of the binary - operator is the difference resulting from the subtraction of the
second operand from the first.
-<p><!--para 7-->
+<p><!--para 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.
-<p><!--para 8-->
+<p><!--para 8 -->
When an expression that has integer type is added to or subtracted from a pointer, the
result has the type of the pointer operand. If the pointer operand points to an element of
an array object, and the array is large enough, the result points to an element offset from
element of the array object, the evaluation shall not produce an overflow; otherwise, the
behavior is undefined. If the result points one past the last element of the array object, it
shall not be used as the operand of a unary * operator that is evaluated.
-<p><!--para 9-->
+<p><!--para 9 -->
When two pointers are subtracted, both shall point to elements of the same array object,
or one past the last element of the array object; the result is the difference of the
subscripts of the two array elements. The size of the result is implementation-defined,
object of type ptrdiff_t. Moreover, if the expression P points either to an element of
an array object or one past the last element of an array object, and the expression Q points
to the last element of the same array object, the expression ((Q)+1)-(P) has the same
-<!--page 96 indent 5-->
+<!--page 96 -->
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.<sup><a href="#note91"><b>91)</b></a></sup>
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE Pointer arithmetic is well defined with pointers to variable length array types.
-<p><!--para 11-->
+<p><!--para 11 -->
<pre>
{
int n = 4, m = 3;
<a name="6.5.7" href="#6.5.7"><h4>6.5.7 Bitwise shift operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
shift-expression:
additive-expression
shift-expression << additive-expression
shift-expression >> additive-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The integer promotions are performed on each of the operands. The type of the result is
that of the promoted left operand. If the value of the right operand is negative or is
greater than or equal to the width of the promoted left operand, the behavior is undefined.
-<!--page 97 indent 4-->
-<p><!--para 4-->
+<!--page 97 -->
+<p><!--para 4 -->
The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits are filled with
zeros. If E1 has an unsigned type, the value of the result is E1 x 2E2 , reduced modulo
one more than the maximum value representable in the result type. If E1 has a signed
type and nonnegative value, and E1 x 2E2 is representable in the result type, then that is
the resulting value; otherwise, the behavior is undefined.
-<p><!--para 5-->
+<p><!--para 5 -->
The result of E1 >> E2 is E1 right-shifted E2 bit positions. If E1 has an unsigned type
or if E1 has a signed type and a nonnegative value, the value of the result is the integral
part of the quotient of E1 / 2E2 . If E1 has a signed type and a negative value, the
<a name="6.5.8" href="#6.5.8"><h4>6.5.8 Relational operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
relational-expression:
shift-expression
relational-expression <= shift-expression
relational-expression >= shift-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
One of the following shall hold:
<ul>
<li> both operands have real type;
incomplete types.
</ul>
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If both of the operands have arithmetic type, the usual arithmetic conversions are
performed.
-<p><!--para 4-->
+<p><!--para 4 -->
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.
-<p><!--para 5-->
+<p><!--para 5 -->
When two pointers are compared, the result depends on the relative locations in the
address space of the objects pointed to. If two pointers to object or incomplete types both
point to the same object, or both point one past the last element of the same array object,
they compare equal. If the objects pointed to are members of the same aggregate object,
pointers to structure members declared later compare greater than pointers to members
declared earlier in the structure, and pointers to array elements with larger subscript
-<!--page 98 indent 4-->
+<!--page 98 -->
values compare greater than pointers to elements of the same array with lower subscript
values. All pointers to members of the same union object compare equal. If the
expression P points to an element of an array object and the expression Q points to the
last element of the same array object, the pointer expression Q+1 compares greater than
P. In all other cases, the behavior is undefined.
-<p><!--para 6-->
+<p><!--para 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.<sup><a href="#note92"><b>92)</b></a></sup>
The result has type int.
<a name="6.5.9" href="#6.5.9"><h4>6.5.9 Equality operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
equality-expression:
relational-expression
equality-expression == relational-expression
equality-expression != relational-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
One of the following shall hold:
<ul>
<li> both operands have arithmetic type;
<li> one operand is a pointer and the other is a null pointer constant.
</ul>
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The == (equal to) and != (not equal to) operators are analogous to the relational
operators except for their lower precedence.<sup><a href="#note93"><b>93)</b></a></sup> Each of the operators yields 1 if the
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.
-<p><!--para 4-->
+<p><!--para 4 -->
If both of the operands have arithmetic type, the usual arithmetic conversions are
performed. Values of complex types are equal if and only if both their real parts are equal
and also their imaginary parts are equal. Any two values of arithmetic types from
(complex) result type determined by the usual arithmetic conversions are equal.
-<!--page 99 indent 4-->
-<p><!--para 5-->
+<!--page 99 -->
+<p><!--para 5 -->
Otherwise, at least one operand is a pointer. If one operand is a pointer and the other is a
null pointer constant, the null pointer constant is converted to the type of the pointer. If
one operand is a pointer to an object or incomplete type and the other is a pointer to a
qualified or unqualified version of void, the former is converted to the type of the latter.
-<p><!--para 6-->
+<p><!--para 6 -->
Two pointers compare equal if and only if both are null pointers, both are pointers to the
same object (including a pointer to an object and a subobject at its beginning) or function,
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.<sup><a href="#note94"><b>94)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 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.
<a name="6.5.10" href="#6.5.10"><h4>6.5.10 Bitwise AND operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
AND-expression:
equality-expression
AND-expression & equality-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the binary & operator is the bitwise AND of the operands (that is, each bit in
the result is set if and only if each of the corresponding bits in the converted operands is
set).
-<!--page 100 indent 4-->
+<!--page 100 -->
<a name="6.5.11" href="#6.5.11"><h4>6.5.11 Bitwise exclusive OR operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
exclusive-OR-expression:
AND-expression
exclusive-OR-expression ^ AND-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the ^ operator is the bitwise exclusive OR of the operands (that is, each bit
in the result is set if and only if exactly one of the corresponding bits in the converted
operands is set).
<a name="6.5.12" href="#6.5.12"><h4>6.5.12 Bitwise inclusive OR operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
inclusive-OR-expression:
exclusive-OR-expression
inclusive-OR-expression | exclusive-OR-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the | operator is the bitwise inclusive OR of the operands (that is, each bit in
the result is set if and only if at least one of the corresponding bits in the converted
operands is set).
-<!--page 101 indent 4-->
+<!--page 101 -->
<a name="6.5.13" href="#6.5.13"><h4>6.5.13 Logical AND operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
logical-AND-expression:
inclusive-OR-expression
logical-AND-expression && inclusive-OR-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have scalar type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The && operator shall yield 1 if both of its operands compare unequal to 0; otherwise, it
yields 0. The result has type int.
-<p><!--para 4-->
+<p><!--para 4 -->
Unlike the bitwise binary & operator, the && operator guarantees left-to-right evaluation;
there is a sequence point after the evaluation of the first operand. If the first operand
compares equal to 0, the second operand is not evaluated.
<a name="6.5.14" href="#6.5.14"><h4>6.5.14 Logical OR operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
logical-OR-expression:
logical-AND-expression
logical-OR-expression || logical-AND-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have scalar type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The || operator shall yield 1 if either of its operands compare unequal to 0; otherwise, it
yields 0. The result has type int.
-<p><!--para 4-->
+<p><!--para 4 -->
Unlike the bitwise | operator, the || operator guarantees left-to-right evaluation; there is
a sequence point after the evaluation of the first operand. If the first operand compares
unequal to 0, the second operand is not evaluated.
-<!--page 102 indent 4-->
+<!--page 102 -->
<a name="6.5.15" href="#6.5.15"><h4>6.5.15 Conditional operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
conditional-expression:
logical-OR-expression
logical-OR-expression ? expression : conditional-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The first operand shall have scalar type.
-<p><!--para 3-->
+<p><!--para 3 -->
One of the following shall hold for the second and third operands:
<ul>
<li> both operands have arithmetic type;
qualified or unqualified version of void.
</ul>
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The first operand is evaluated; there is a sequence point after its evaluation. The second
operand is evaluated only if the first compares unequal to 0; the third operand is evaluated
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.<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.
-<p><!--para 5-->
+<p><!--para 5 -->
If both the second and third operands have arithmetic type, the result type that would be
determined by the usual arithmetic conversions, were they applied to those two operands,
is the type of the result. If both the operands have structure or union type, the result has
that type. If both operands have void type, the result has void type.
-<p><!--para 6-->
+<p><!--para 6 -->
If both the second and third operands are pointers or one is a null pointer constant and the
other is a pointer, the result type is a pointer to a type qualified with all the type qualifiers
of the types pointed-to by both operands. Furthermore, if both operands are pointers to
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
-<!--page 103 indent 4-->
+<!--page 103 -->
pointer to an appropriately qualified version of void.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE The common type that results when the second and third operands are pointers is determined
in two independent stages. The appropriate qualifiers, for example, do not depend on whether the two
pointers have compatible types.
-<p><!--para 8-->
+<p><!--para 8 -->
Given the declarations
<pre>
const void *c_vp;
<a name="6.5.16" href="#6.5.16"><h4>6.5.16 Assignment operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
assignment-expression:
conditional-expression
assignment-operator: one of
= *= /= %= += -= <<= >>= &= ^= |=</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An assignment operator shall have a modifiable lvalue as its left operand.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
An assignment operator stores a value in the object designated by the left operand. An
assignment expression has the value of the left operand after the assignment, but is not an
lvalue. The type of an assignment expression is the type of the left operand unless the
left operand has qualified type, in which case it is the unqualified version of the type of
the left operand. The side effect of updating the stored value of the left operand shall
occur between the previous and the next sequence point.
-<p><!--para 4-->
+<p><!--para 4 -->
The order of evaluation of the operands is unspecified. If an attempt is made to modify
the result of an assignment operator or to access it after the next sequence point, the
behavior is undefined.
-<!--page 104 indent 4-->
+<!--page 104 -->
<a name="6.5.16.1" href="#6.5.16.1"><h5>6.5.16.1 Simple assignment</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
One of the following shall hold:<sup><a href="#note96"><b>96)</b></a></sup>
<ul>
<li> the left operand has qualified or unqualified arithmetic type and the right has
<li> the left operand has type _Bool and the right is a pointer.
</ul>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
In simple assignment (=), the value of the right operand is converted to the type of the
assignment expression and replaces the value stored in the object designated by the left
operand.
-<p><!--para 3-->
+<p><!--para 3 -->
If the value being stored in an object is read from another object that overlaps in any way
the storage of the first object, then the overlap shall be exact and the two objects shall
have qualified or unqualified versions of a compatible type; otherwise, the behavior is
undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE 1 In the program fragment
<pre>
int f(void);
-<!--page 105 indent 4-->
+<!--page 105 -->
negative, so the operands of the comparison can never compare equal. Therefore, for full portability, the
variable c should be declared as int.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 2 In the fragment:
<pre>
char c;
of the expression enclosed in parentheses is then converted to the type of the outer assignment expression,
that is, long int type.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 3 Consider the fragment:
<pre>
const char **cpp;
<a name="6.5.16.2" href="#6.5.16.2"><h5>6.5.16.2 Compound assignment</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
For the operators += and -= only, either the left operand shall be a pointer to an object
type and the right shall have integer type, or the left operand shall have qualified or
unqualified arithmetic type and the right shall have arithmetic type.
-<p><!--para 2-->
+<p><!--para 2 -->
For the other operators, each operand shall have arithmetic type consistent with those
allowed by the corresponding binary operator.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A compound assignment of the form E1 op = E2 differs from the simple assignment
expression E1 = E1 op (E2) only in that the lvalue E1 is evaluated only once.
-<!--page 106 indent 4-->
+<!--page 106 -->
<a name="6.5.17" href="#6.5.17"><h4>6.5.17 Comma operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
expression:
assignment-expression
expression , assignment-expression</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The left operand of a comma operator is evaluated as a void expression; there is a
sequence point after its evaluation. Then the right operand is evaluated; the result has its
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.
-<p><!--para 3-->
+<p><!--para 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
of initializers). On the other hand, it can be used within a parenthesized expression or within the second
-<!--page 107 indent 4-->
+<!--page 107 -->
<h6>footnotes</h6>
<p><small><a name="note97" href="#note97">97)</a> A comma operator does not yield an lvalue.
<a name="6.6" href="#6.6"><h3>6.6 Constant expressions</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
constant-expression:
conditional-expression</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A constant expression can be evaluated during translation rather than runtime, and
accordingly may be used in any place that a constant may be.
<h6>Constraints</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Constant expressions shall not contain assignment, increment, decrement, function-call,
or comma operators, except when they are contained within a subexpression that is not
evaluated.<sup><a href="#note98"><b>98)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
Each constant expression shall evaluate to a constant that is in the range of representable
values for its type.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
An expression that evaluates to a constant is required in several contexts. If a floating
expression is evaluated in the translation environment, the arithmetic precision and range
shall be at least as great as if the expression were being evaluated in the execution
environment.
-<p><!--para 6-->
+<p><!--para 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
convert arithmetic types to integer types, except as part of an operand to the sizeof
operator.
-<p><!--para 7-->
+<p><!--para 7 -->
More latitude is permitted for constant expressions in initializers. Such a constant
expression shall be, or evaluate to, one of the following:
<ul>
-<!--page 108 indent 5-->
+<!--page 108 -->
<li> an address constant, or
<li> an address constant for an object type plus or minus an integer constant expression.
</ul>
-<p><!--para 8-->
+<p><!--para 8 -->
An arithmetic constant expression shall have arithmetic type and shall only have
operands that are integer constants, floating constants, enumeration constants, character
constants, and sizeof expressions. Cast operators in an arithmetic constant expression
shall only convert arithmetic types to arithmetic types, except as part of an operand to a
sizeof operator whose result is an integer constant.
-<p><!--para 9-->
+<p><!--para 9 -->
An address constant is a null pointer, a pointer to an lvalue designating an object of static
storage duration, or a pointer to a function designator; it shall be created explicitly using
the unary & operator or an integer constant cast to pointer type, or implicitly by the use of
and -> operators, the address & and indirection * unary operators, and pointer casts may
be used in the creation of an address constant, but the value of an object shall not be
accessed by use of these operators.
-<p><!--para 10-->
+<p><!--para 10 -->
An implementation may accept other forms of constant expressions.
-<p><!--para 11-->
+<p><!--para 11 -->
The semantic rules for the evaluation of a constant expression are the same as for
nonconstant expressions.<sup><a href="#note100"><b>100)</b></a></sup>
<p><b> Forward references</b>: array declarators (<a href="#6.7.5.2">6.7.5.2</a>), initialization (<a href="#6.7.8">6.7.8</a>).
-<!--page 109 indent 4-->
+<!--page 109 -->
<h6>footnotes</h6>
<p><small><a name="note98" href="#note98">98)</a> The operand of a sizeof operator is usually not evaluated (<a href="#6.5.3.4">6.5.3.4</a>).
<a name="6.7" href="#6.7"><h3>6.7 Declarations</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
declaration:
declaration-specifiers init-declarator-listopt ;
declarator
declarator = initializer</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A declaration shall declare at least a declarator (other than the parameters of a function or
the members of a structure or union), a tag, or the members of an enumeration.
-<p><!--para 3-->
+<p><!--para 3 -->
If an identifier has no linkage, there shall be no more than one declaration of the identifier
(in a declarator or type specifier) with the same scope and in the same name space, except
for tags as specified in <a href="#6.7.2.3">6.7.2.3</a>.
-<p><!--para 4-->
+<p><!--para 4 -->
All declarations in the same scope that refer to the same object or function shall specify
compatible types.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
A declaration specifies the interpretation and attributes of a set of identifiers. A definition
of an identifier is a declaration for that identifier that:
<ul>
<li> for an enumeration constant or typedef name, is the (only) declaration of the
identifier.
</ul>
-<p><!--para 6-->
+<p><!--para 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
-<!--page 110 indent 4-->
+<!--page 110 -->
additional type information, or an initializer, or both. The declarators contain the
identifiers (if any) being declared.
-<p><!--para 7-->
+<p><!--para 7 -->
If an identifier for an object is declared with no linkage, the type for the object shall be
complete by the end of its declarator, or by the end of its init-declarator if it has an
initializer; in the case of function parameters (including in prototypes), it is the adjusted
<a name="6.7.1" href="#6.7.1"><h4>6.7.1 Storage-class specifiers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
storage-class-specifier:
typedef
auto
register</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
At most, one storage-class specifier may be given in the declaration specifiers in a
declaration.<sup><a href="#note102"><b>102)</b></a></sup>
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The typedef specifier is called a ''storage-class specifier'' for syntactic convenience
only; it is discussed in <a href="#6.7.7">6.7.7</a>. The meanings of the various linkages and storage durations
were discussed in <a href="#6.2.2">6.2.2</a> and <a href="#6.2.4">6.2.4</a>.
-<p><!--para 4-->
+<p><!--para 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.<sup><a href="#note103"><b>103)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
The declaration of an identifier for a function that has block scope shall have no explicit
storage-class specifier other than extern.
-<!--page 111 indent 4-->
-<p><!--para 6-->
+<!--page 111 -->
+<p><!--para 6 -->
If an aggregate or union object is declared with a storage-class specifier other than
typedef, the properties resulting from the storage-class specifier, except with respect to
linkage, also apply to the members of the object, and so on recursively for any aggregate
<a name="6.7.2" href="#6.7.2"><h4>6.7.2 Type specifiers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
type-specifier:
void
enum-specifier
typedef-name</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
At least one type specifier shall be given in the declaration specifiers in each declaration,
and in the specifier-qualifier list in each struct declaration and type name. Each list of
type specifiers shall be one of the following sets (delimited by commas, when there is
<li> short, signed short, short int, or signed short int
<li> unsigned short, or unsigned short int
<li> int, signed, or signed int
-<!--page 112 indent 4-->
+<!--page 112 -->
<li> unsigned, or unsigned int
<li> long, signed long, long int, or signed long int
<li> unsigned long, or unsigned long int
<li> enum specifier
<li> typedef name
</ul>
-<p><!--para 3-->
+<p><!--para 3 -->
The type specifier _Complex shall not be used if the implementation does not provide
complex types.<sup><a href="#note104"><b>104)</b></a></sup>
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
Specifiers for structures, unions, and enumerations are discussed in <a href="#6.7.2.1">6.7.2.1</a> through
<a href="#6.7.2.3">6.7.2.3</a>. Declarations of typedef names are discussed in <a href="#6.7.7">6.7.7</a>. The characteristics of the
other types are discussed in <a href="#6.2.5">6.2.5</a>.
-<p><!--para 5-->
+<p><!--para 5 -->
Each of the comma-separated sets designates the same type, except that for bit-fields, it is
implementation-defined whether the specifier int designates the same type as signed
int or the same type as unsigned int.
-<!--page 113 indent 4-->
+<!--page 113 -->
<h6>footnotes</h6>
<p><small><a name="note104" href="#note104">104)</a> Freestanding implementations are not required to provide complex types. *
<a name="6.7.2.1" href="#6.7.2.1"><h5>6.7.2.1 Structure and union specifiers</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
struct-or-union-specifier:
struct-or-union identifieropt { struct-declaration-list }
declarator
declaratoropt : constant-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A structure or union shall not contain a member with incomplete or function type (hence,
a structure shall not contain an instance of itself, but may contain a pointer to an instance
of itself), except that the last member of a structure with more than one named member
may have incomplete array type; such a structure (and any union containing, possibly
recursively, a member that is such a structure) shall not be a member of a structure or an
element of an array.
-<p><!--para 3-->
+<p><!--para 3 -->
The expression that specifies the width of a bit-field shall be an integer constant
expression with a nonnegative value that does not exceed the width of an object of the
type that would be specified were the colon and expression omitted. If the value is zero,
the declaration shall have no declarator.
-<p><!--para 4-->
+<p><!--para 4 -->
A bit-field shall have a type that is a qualified or unqualified version of _Bool, signed
int, unsigned int, or some other implementation-defined type.
-<!--page 114 indent 5-->
+<!--page 114 -->
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
As discussed in <a href="#6.2.5">6.2.5</a>, a structure is a type consisting of a sequence of members, whose
storage is allocated in an ordered sequence, and a union is a type consisting of a sequence
of members whose storage overlap.
-<p><!--para 6-->
+<p><!--para 6 -->
Structure and union specifiers have the same form. The keywords struct and union
indicate that the type being specified is, respectively, a structure type or a union type.
-<p><!--para 7-->
+<p><!--para 7 -->
The presence of a struct-declaration-list in a struct-or-union-specifier declares a new type,
within a translation unit. The struct-declaration-list is a sequence of declarations for the
members of the structure or union. If the struct-declaration-list contains no named
members, the behavior is undefined. The type is incomplete until after the } that
terminates the list.
-<p><!--para 8-->
+<p><!--para 8 -->
A member of a structure or union may have any object type other than a variably
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.
-<p><!--para 9-->
+<p><!--para 9 -->
A bit-field is interpreted as a signed or unsigned integer type consisting of the specified
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.
-<p><!--para 10-->
+<p><!--para 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
structure shall be packed into adjacent bits of the same unit. If insufficient space remains,
implementation-defined. The order of allocation of bit-fields within a unit (high-order to
low-order or low-order to high-order) is implementation-defined. The alignment of the
addressable storage unit is unspecified.
-<p><!--para 11-->
+<p><!--para 11 -->
A bit-field declaration with no declarator, but only a colon and a width, indicates an
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.
-<!--page 115 indent 5-->
-<p><!--para 12-->
+<!--page 115 -->
+<p><!--para 12 -->
Each non-bit-field member of a structure or union object is aligned in an implementation-
defined manner appropriate to its type.
-<p><!--para 13-->
+<p><!--para 13 -->
Within a structure object, the non-bit-field members and the units in which bit-fields
reside have addresses that increase in the order in which they are declared. A pointer to a
structure object, suitably converted, points to its initial member (or if that member is a
bit-field, then to the unit in which it resides), and vice versa. There may be unnamed
padding within a structure object, but not at its beginning.
-<p><!--para 14-->
+<p><!--para 14 -->
The size of a union is sufficient to contain the largest of its members. The value of at
most one of the members can be stored in a union object at any time. A pointer to a
union object, suitably converted, points to each of its members (or if a member is a bit-
field, then to the unit in which it resides), and vice versa.
-<p><!--para 15-->
+<p><!--para 15 -->
There may be unnamed padding at the end of a structure or union.
-<p><!--para 16-->
+<p><!--para 16 -->
As a special case, the last element of a structure with more than one named member may
have an incomplete array type; this is called a flexible array member. In most situations,
the flexible array member is ignored. In particular, the size of the structure is as if the
from that of the replacement array. If this array would have no elements, it behaves as if
it had one element but the behavior is undefined if any attempt is made to access that
element or to generate a pointer one past it.
-<p><!--para 17-->
+<p><!--para 17 -->
EXAMPLE After the declaration:
<pre>
struct s { int n; double d[]; };</pre>
struct { int n; double d[m]; } *p;</pre>
(there are circumstances in which this equivalence is broken; in particular, the offsets of member d might
not be the same).
-<p><!--para 18-->
+<p><!--para 18 -->
Following the above declaration:
-<!--page 116 indent 5-->
+<!--page 116 -->
<pre>
struct s t1 = { 0 }; // valid
struct s t2 = { 1, { <a href="#4.2">4.2</a> }}; // invalid
sizeof (struct s) >= offsetof(struct s, d) + sizeof (double)</pre>
in which case the assignment would be legitimate. Nevertheless, it cannot appear in strictly conforming
code.
-<p><!--para 19-->
+<p><!--para 19 -->
After the further declaration:
<pre>
struct ss { int n; };</pre>
sizeof (struct s) >= sizeof (struct ss)
sizeof (struct s) >= offsetof(struct s, d)</pre>
are always equal to 1.
-<p><!--para 20-->
+<p><!--para 20 -->
If sizeof (double) is 8, then after the following code is executed:
<pre>
struct s *s1;
s2 = malloc(sizeof (struct s) + 46);</pre>
and assuming that the calls to malloc succeed, the objects pointed to by s1 and s2 behave, for most
purposes, as if the identifiers had been declared as:
-<p><!--para 21-->
+<p><!--para 21 -->
<pre>
struct { int n; double d[8]; } *s1;
struct { int n; double d[5]; } *s2;</pre>
<pre>
struct { int n; double d[1]; } *s1, *s2;</pre>
and:
-<p><!--para 22-->
+<p><!--para 22 -->
<pre>
double *dp;
dp = &(s1->d[0]); // valid
of the structure, they might be copied or simply overwritten with indeterminate values.
<p><b> Forward references</b>: tags (<a href="#6.7.2.3">6.7.2.3</a>).
-<!--page 117 indent 4-->
+<!--page 117 -->
<h6>footnotes</h6>
<p><small><a name="note105" href="#note105">105)</a> A structure or union can not contain a member with a variably modified type because member names
<a name="6.7.2.2" href="#6.7.2.2"><h5>6.7.2.2 Enumeration specifiers</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
enum-specifier:
enum identifieropt { enumerator-list }
enumeration-constant
enumeration-constant = constant-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The expression that defines the value of an enumeration constant shall be an integer
constant expression that has a value representable as an int.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The identifiers in an enumerator list are declared as constants that have type int and
may appear wherever such are permitted.<sup><a href="#note109"><b>109)</b></a></sup> An enumerator with = defines its
enumeration constant as the value of the constant expression. If the first enumerator has
adding 1 to the value of the previous enumeration constant. (The use of enumerators with
= 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.
-<p><!--para 4-->
+<p><!--para 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,<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
-<!--page 118 indent 4-->
-<p><!--para 5-->
+<!--page 118 -->
+<p><!--para 5 -->
EXAMPLE The following fragment:
<pre>
enum hue { chartreuse, burgundy, claret=20, winedark };
<a name="6.7.2.3" href="#6.7.2.3"><h5>6.7.2.3 Tags</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A specific type shall have its content defined at most once.
-<p><!--para 2-->
+<p><!--para 2 -->
Where two declarations that use the same tag declare the same type, they shall both use
the same choice of struct, union, or enum.
-<p><!--para 3-->
+<p><!--para 3 -->
A type specifier of the form
<pre>
enum identifier</pre>
without an enumerator list shall only appear after the type it specifies is complete.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
All declarations of structure, union, or enumerated types that have the same scope and
use the same tag declare the same type. The type is incomplete<sup><a href="#note111"><b>111)</b></a></sup> until the closing brace
of the list defining the content, and complete thereafter.
-<p><!--para 5-->
+<p><!--para 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
enumerated type which does not include a tag declares a distinct type.
-<p><!--para 6-->
+<p><!--para 6 -->
A type specifier of the form
<pre>
struct-or-union identifieropt { struct-declaration-list }</pre>
enum identifier { enumerator-list , }</pre>
declares a structure, union, or enumerated type. The list defines the structure content,
-<!--page 119 indent 5-->
+<!--page 119 -->
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.
-<p><!--para 7-->
+<p><!--para 7 -->
A declaration of the form
<pre>
struct-or-union identifier ;</pre>
specifies a structure or union type and declares the identifier as a tag of that type.<sup><a href="#note113"><b>113)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
If a type specifier of the form
<pre>
struct-or-union identifier</pre>
occurs other than as part of one of the above forms, and no other declaration of the
identifier as a tag is visible, then it declares an incomplete structure or union type, and
declares the identifier as the tag of that type.113)
-<p><!--para 9-->
+<p><!--para 9 -->
If a type specifier of the form
<pre>
struct-or-union identifier</pre>
occurs other than as part of one of the above forms, and a declaration of the identifier as a
tag is visible, then it specifies the same type as that other declaration, and does not
redeclare the tag.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 1 This mechanism allows declaration of a self-referential structure.
<pre>
struct tnode {
these declarations, the expression sp->left refers to the left struct tnode pointer of the object to
which sp points; the expression s.right->count designates the count member of the right struct
tnode pointed to from s.
-<p><!--para 11-->
+<p><!--para 11 -->
The following alternative formulation uses the typedef mechanism:
-<!--page 120 indent 5-->
+<!--page 120 -->
<pre>
typedef struct tnode TNODE;
struct tnode {
};
TNODE s, *sp;</pre>
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE 2 To illustrate the use of prior declaration of a tag to specify a pair of mutually referential
structures, the declarations
<pre>
<a name="6.7.3" href="#6.7.3"><h4>6.7.3 Type qualifiers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
type-qualifier:
const
restrict
volatile</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Types other than pointer types derived from object or incomplete types shall not be
restrict-qualified.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The properties associated with qualified types are meaningful only for expressions that
are lvalues.<sup><a href="#note114"><b>114)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 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.
-<!--page 121 indent 5-->
-<p><!--para 5-->
+<!--page 121 -->
+<p><!--para 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.<sup><a href="#note115"><b>115)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 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,
object shall agree with that prescribed by the abstract machine, except as modified by the
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.
-<p><!--para 7-->
+<p><!--para 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.<sup><a href="#note117"><b>117)</b></a></sup> The intended
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).
-<p><!--para 8-->
+<p><!--para 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.<sup><a href="#note118"><b>118)</b></a></sup>
-<p><!--para 9-->
+<p><!--para 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.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 1 An object declared
<pre>
extern const volatile int real_time_clock;</pre>
-<!--page 122 indent 5-->
-<p><!--para 11-->
+<!--page 122 -->
+<p><!--para 11 -->
EXAMPLE 2 The following declarations and expressions illustrate the behavior when type qualifiers
modify an aggregate type:
<pre>
</small>
<a name="6.7.3.1" href="#6.7.3.1"><h5>6.7.3.1 Formal definition of restrict</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Let D be a declaration of an ordinary identifier that provides a means of designating an
object P as a restrict-qualified pointer to type T.
-<p><!--para 2-->
+<p><!--para 2 -->
If D appears inside a block and does not have storage class extern, let B denote the
block. If D appears in the list of parameter declarations of a function definition, let B
denote the associated block. Otherwise, let B denote the block of main (or the block of
whatever function is called at program startup in a freestanding environment).
-<p><!--para 3-->
+<p><!--para 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.<sup><a href="#note119"><b>119)</b></a></sup>
Note that ''based'' is defined only for expressions with pointer types.
-<p><!--para 4-->
+<p><!--para 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),
then the following requirements apply: T shall not be const-qualified. Every other lvalue
object P2, associated with block B2, then either the execution of B2 shall begin before
the execution of B, or the execution of B2 shall end prior to the assignment. If these
requirements are not met, then the behavior is undefined.
-<p><!--para 5-->
+<p><!--para 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
-<!--page 123 indent 5-->
+<!--page 123 -->
associated with B.
-<p><!--para 6-->
+<p><!--para 6 -->
A translator is free to ignore any or all aliasing implications of uses of restrict.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1 The file scope declarations
<pre>
int * restrict a;
assert that if an object is accessed using one of a, b, or c, and that object is modified anywhere in the
program, then it is never accessed using either of the other two.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 2 The function parameter declarations in the following example
<pre>
void f(int n, int * restrict p, int * restrict q)
}</pre>
assert that, during each execution of the function, if an object is accessed through one of the pointer
parameters, then it is not also accessed through the other.
-<p><!--para 9-->
+<p><!--para 9 -->
The benefit of the restrict qualifiers is that they enable a translator to make an effective dependence
analysis of function f without examining any of the calls of f in the program. The cost is that the
programmer has to examine all of those calls to ensure that none give undefined behavior. For example, the
f(50, d + 1, d); // undefined behavior
}</pre>
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 3 The function parameter declarations
<pre>
void h(int n, int * restrict p, int * restrict q, int * restrict r)
are disjoint arrays, a call of the form h(100, a, b, b) has defined behavior, because array b is not
modified within function h.
-<p><!--para 11-->
+<p><!--para 11 -->
EXAMPLE 4 The rule limiting assignments between restricted pointers does not distinguish between a
function call and an equivalent nested block. With one exception, only ''outer-to-inner'' assignments
between restricted pointers declared in nested blocks have defined behavior.
-<!--page 124 indent 5-->
-<p><!--para 12-->
+<!--page 124 -->
+<p><!--para 12 -->
<pre>
{
int * restrict p1;
<a name="6.7.4" href="#6.7.4"><h4>6.7.4 Function specifiers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
function-specifier:
inline</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Function specifiers shall be used only in the declaration of an identifier for a function.
-<p><!--para 3-->
+<p><!--para 3 -->
An inline definition of a function with external linkage shall not contain a definition of a
modifiable object with static storage duration, and shall not contain a reference to an
identifier with internal linkage.
-<p><!--para 4-->
+<p><!--para 4 -->
In a hosted environment, the inline function specifier shall not appear in a declaration
of main.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
A function declared with an inline function specifier is an inline function. The
function specifier may appear more than once; the behavior is the same as if it appeared
only once. Making a function an inline function suggests that calls to the function be as
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>
-<p><!--para 6-->
+<p><!--para 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
-<!--page 125 indent 4-->
+<!--page 125 -->
function specifier, then it shall also be defined in the same translation unit. If all of the
file scope declarations for a function in a translation unit include the inline function
specifier without extern, then the definition in that translation unit is an inline
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.<sup><a href="#note122"><b>122)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 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.
-<p><!--para 8-->
+<p><!--para 8 -->
<pre>
inline double fahr(double t)
{
<p><b> Forward references</b>: function definitions (<a href="#6.9.1">6.9.1</a>).
-<!--page 126 indent 4-->
+<!--page 126 -->
<h6>footnotes</h6>
<p><small><a name="note120" href="#note120">120)</a> By using, for example, an alternative to the usual function call mechanism, such as ''inline
<a name="6.7.5" href="#6.7.5"><h4>6.7.5 Declarators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
declarator:
pointeropt direct-declarator
identifier
identifier-list , identifier</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each declarator declares one identifier, and asserts that when an operand of the same
form as the declarator appears in an expression, it designates a function or object with the
scope, storage duration, and type indicated by the declaration specifiers.
-<p><!--para 3-->
+<p><!--para 3 -->
A full declarator is a declarator that is not part of another declarator. The end of a full
declarator is a sequence point. If, in the nested sequence of declarators in a full
-<!--page 127 indent 4-->
+<!--page 127 -->
declarator, there is a declarator specifying a variable length array type, the type specified
by the full declarator is said to be variably modified. Furthermore, any type derived by
declarator type derivation from a variably modified type is itself variably modified.
-<p><!--para 4-->
+<p><!--para 4 -->
In the following subclauses, consider a declaration
<pre>
T D1</pre>
where T contains the declaration specifiers that specify a type T (such as int) and D1 is
a declarator that contains an identifier ident. The type specified for the identifier ident in
the various forms of declarator is described inductively using this notation.
-<p><!--para 5-->
+<p><!--para 5 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
identifier</pre>
then the type specified for ident is T .
-<p><!--para 6-->
+<p><!--para 6 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
( D )</pre>
parentheses is identical to the unparenthesized declarator, but the binding of complicated
declarators may be altered by parentheses.
Implementation limits
-<p><!--para 7-->
+<p><!--para 7 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, an implementation may limit the number of pointer, array, and
function declarators that modify an arithmetic, structure, union, or incomplete type, either
directly or via one or more typedefs.
<a name="6.7.5.1" href="#6.7.5.1"><h5>6.7.5.1 Pointer declarators</h5></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
* type-qualifier-listopt D</pre>
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list type-qualifier-list
pointer to T ''. For each type qualifier in the list, ident is a so-qualified pointer.
-<p><!--para 2-->
+<p><!--para 2 -->
For two pointer types to be compatible, both shall be identically qualified and both shall
be pointers to compatible types.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE The following pair of declarations demonstrates the difference between a ''variable pointer
to a constant value'' and a ''constant pointer to a variable value''.
-<!--page 128 indent 4-->
+<!--page 128 -->
<pre>
const int *ptr_to_constant;
int *const constant_ptr;</pre>
but ptr_to_constant itself may be changed to point to another object. Similarly, the contents of the
int pointed to by constant_ptr may be modified, but constant_ptr itself shall always point to the
same location.
-<p><!--para 4-->
+<p><!--para 4 -->
The declaration of the constant pointer constant_ptr may be clarified by including a definition for the
type ''pointer to int''.
<pre>
<a name="6.7.5.2" href="#6.7.5.2"><h5>6.7.5.2 Array declarators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
In addition to optional type qualifiers and the keyword static, the [ and ] may delimit
an expression or *. If they delimit an expression (which specifies the size of an array), the
expression shall have an integer type. If the expression is a constant expression, it shall
type. The optional type qualifiers and the keyword static shall appear only in a
declaration of a function parameter with an array type, and then only in the outermost
array type derivation.
-<p><!--para 2-->
+<p><!--para 2 -->
An ordinary identifier (as defined in <a href="#6.2.3">6.2.3</a>) that has a variably modified type shall have
either block scope and no linkage or function prototype scope. If an identifier is declared
to be an object with static storage duration, it shall not have a variable length array type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If, in the declaration ''T D1'', D1 has one of the forms:
<pre>
D[ type-qualifier-listopt assignment-expressionopt ]
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list array of T ''.<sup><a href="#note123"><b>123)</b></a></sup>
(See <a href="#6.7.5.3">6.7.5.3</a> for the meaning of the optional type qualifiers and the keyword static.)
-<p><!--para 4-->
+<p><!--para 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;<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
-<!--page 129 indent 4-->
+<!--page 129 -->
type has a known constant size, the array type is not a variable length array type;
otherwise, the array type is a variable length array type.
-<p><!--para 5-->
+<p><!--para 5 -->
If the size is an expression that is not an integer constant expression: if it occurs in a
declaration at function prototype scope, it is treated as if it were replaced by *; otherwise,
each time it is evaluated it shall have a value greater than zero. The size of each instance
expression is part of the operand of a sizeof operator and changing the value of the
size expression would not affect the result of the operator, it is unspecified whether or not
the size expression is evaluated.
-<p><!--para 6-->
+<p><!--para 6 -->
For two array types to be compatible, both shall have compatible element types, and if
both size specifiers are present, and are integer constant expressions, then both size
specifiers shall have the same constant value. If the two array types are used in a context
which requires them to be compatible, it is undefined behavior if the two size specifiers
evaluate to unequal values.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1
<pre>
float fa[11], *afp[17];</pre>
declares an array of float numbers and an array of pointers to float numbers.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 2 Note the distinction between the declarations
<pre>
extern int *x;
The first declares x to be a pointer to int; the second declares y to be an array of int of unspecified size
(an incomplete type), the storage for which is defined elsewhere.
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 3 The following declarations demonstrate the compatibility rules for variably modified types.
<pre>
extern int n;
-<!--page 130 indent 5-->
-<p><!--para 10-->
+<!--page 130 -->
+<p><!--para 10 -->
EXAMPLE 4 All declarations of variably modified (VM) types have to be at either block scope or
function prototype scope. Array objects declared with the static or extern storage-class specifier
cannot have a variable length array (VLA) type. However, an object declared with the static storage-
<a name="6.7.5.3" href="#6.7.5.3"><h5>6.7.5.3 Function declarators (including prototypes)</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A function declarator shall not specify a return type that is a function type or an array
type.
-<p><!--para 2-->
+<p><!--para 2 -->
The only storage-class specifier that shall occur in a parameter declaration is register.
-<p><!--para 3-->
+<p><!--para 3 -->
An identifier list in a function declarator that is not part of a definition of that function
shall be empty.
-<p><!--para 4-->
+<p><!--para 4 -->
After adjustment, the parameters in a parameter type list in a function declarator that is
part of a definition of that function shall not have incomplete type.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
D( parameter-type-list )</pre>
or
-<!--page 131 indent 5-->
+<!--page 131 -->
<pre>
D( identifier-listopt )</pre>
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list function returning
T ''.
-<p><!--para 6-->
+<p><!--para 6 -->
A parameter type list specifies the types of, and may declare identifiers for, the
parameters of the function.
-<p><!--para 7-->
+<p><!--para 7 -->
A declaration of a parameter as ''array of type'' shall be adjusted to ''qualified pointer to
type'', where the type qualifiers (if any) are those specified within the [ and ] of the
array type derivation. If the keyword static also appears within the [ and ] of the
array type derivation, then for each call to the function, the value of the corresponding
actual argument shall provide access to the first element of an array with at least as many
elements as specified by the size expression.
-<p><!--para 8-->
+<p><!--para 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>.
-<p><!--para 9-->
+<p><!--para 9 -->
If the list terminates with an ellipsis (, ...), no information about the number or types
of the parameters after the comma is supplied.<sup><a href="#note125"><b>125)</b></a></sup>
-<p><!--para 10-->
+<p><!--para 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.
-<p><!--para 11-->
+<p><!--para 11 -->
If, in a parameter declaration, an identifier can be treated either as a typedef name or as a
parameter name, it shall be taken as a typedef name.
-<p><!--para 12-->
+<p><!--para 12 -->
If the function declarator is not part of a definition of that function, parameters may have
incomplete type and may use the [*] notation in their sequences of declarator specifiers
to specify variable length array types.
-<p><!--para 13-->
+<p><!--para 13 -->
The storage-class specifier in the declaration specifiers for a parameter declaration, if
present, is ignored unless the declared parameter is one of the members of the parameter
type list for a function definition.
-<p><!--para 14-->
+<p><!--para 14 -->
An identifier list declares only the identifiers of the parameters of the function. An empty
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.<sup><a href="#note126"><b>126)</b></a></sup>
-<p><!--para 15-->
+<p><!--para 15 -->
For two function types to be compatible, both shall specify compatible return types.<sup><a href="#note127"><b>127)</b></a></sup>
-<!--page 132 indent 5-->
+<!--page 132 -->
Moreover, the parameter type lists, if both are present, shall agree in the number of
parameters and in use of the ellipsis terminator; corresponding parameters shall have
compatible types. If one type has a parameter type list and the other type is specified by a
compatibility and of a composite type, each parameter declared with function or array
type is taken as having the adjusted type and each parameter declared with qualified type
is taken as having the unqualified version of its declared type.)
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE 1 The declaration
<pre>
int f(void), *fip(), (*pfi)();</pre>
and then using indirection through the pointer result to yield an int. In the declarator (*pfi)(), the
extra parentheses are necessary to indicate that indirection through a pointer to a function yields a function
designator, which is then used to call the function; it returns an int.
-<p><!--para 17-->
+<p><!--para 17 -->
If the declaration occurs outside of any function, the identifiers have file scope and external linkage. If the
declaration occurs inside a function, the identifiers of the functions f and fip have block scope and either
internal or external linkage (depending on what file scope declarations for these identifiers are visible), and
the identifier of the pointer pfi has block scope and no linkage.
-<p><!--para 18-->
+<p><!--para 18 -->
EXAMPLE 2 The declaration
<pre>
int (*apfi[3])(int *x, int *y);</pre>
parameters that are pointers to int. The identifiers x and y are declared for descriptive purposes only and
go out of scope at the end of the declaration of apfi.
-<p><!--para 19-->
+<p><!--para 19 -->
EXAMPLE 3 The declaration
<pre>
int (*fpfi(int (*)(long), int))(int, ...);</pre>
parameters: a pointer to a function returning an int (with one parameter of type long int), and an int.
The pointer returned by fpfi points to a function that has one int parameter and accepts zero or more
additional arguments of any type.
-<!--page 133 indent 5-->
-<p><!--para 20-->
+<!--page 133 -->
+<p><!--para 20 -->
EXAMPLE 4 The following prototype has a variably modified parameter.
<pre>
void addscalar(int n, int m,
a[i][j] += x;
}</pre>
-<p><!--para 21-->
+<p><!--para 21 -->
EXAMPLE 5 The following are all compatible function prototype declarators.
<pre>
double maximum(int n, int m, double a[n][m]);
non-null pointer to the first of at least three arrays of 5 doubles, which the others do not.)
<p><b> Forward references</b>: function definitions (<a href="#6.9.1">6.9.1</a>), type names (<a href="#6.7.6">6.7.6</a>).
-<!--page 134 indent 4-->
+<!--page 134 -->
<h6>footnotes</h6>
<p><small><a name="note125" href="#note125">125)</a> The macros defined in the <a href="#7.15"><stdarg.h></a> header (<a href="#7.15">7.15</a>) may be used to access arguments that
<a name="6.7.6" href="#6.7.6"><h4>6.7.6 Type names</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
type-name:
specifier-qualifier-list abstract-declaratoropt
direct-abstract-declaratoropt [ * ]
direct-abstract-declaratoropt ( parameter-type-listopt )</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
In several contexts, it is necessary to specify a type. This is accomplished using a type
name, which is syntactically a declaration for a function or an object of that type that
omits the identifier.<sup><a href="#note128"><b>128)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE The constructions
<pre>
(a) int
-<!--page 135 indent 4-->
+<!--page 135 -->
<h6>footnotes</h6>
<p><small><a name="note128" href="#note128">128)</a> As indicated by the syntax, empty parentheses in a type name are interpreted as ''function with no
<a name="6.7.7" href="#6.7.7"><h4>6.7.7 Type definitions</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
typedef-name:
identifier</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If a typedef name specifies a variably modified type then it shall have block scope.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
In a declaration whose storage-class specifier is typedef, each declarator defines an
identifier to be a typedef name that denotes the type specified for the identifier in the way
described in <a href="#6.7.5">6.7.5</a>. Any array size expressions associated with variable length array
type-list T '' where the derived-declarator-type-list is specified by the declarators of D. A
typedef name shares the same name space as other identifiers declared in ordinary
declarators.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE 1 After
<pre>
typedef int MILES, KLICKSP();
parameter specification returning int'', and that of x and z is the specified structure; zp is a pointer to
such a structure. The object distance has a type compatible with any other int object.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 2 After the declarations
<pre>
typedef struct s1 { int x; } t1, *tp1;
typedef struct s2 { int x; } t2, *tp2;</pre>
type t1 and the type pointed to by tp1 are compatible. Type t1 is also compatible with type struct
s1, but not compatible with the types struct s2, t2, the type pointed to by tp2, or int.
-<!--page 136 indent 4-->
-<p><!--para 6-->
+<!--page 136 -->
+<p><!--para 6 -->
EXAMPLE 3 The following obscure constructions
<pre>
typedef signed int t;
with type pointer to function returning signed int with one unnamed parameter with type signed
int'', and an identifier t with type long int.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 4 On the other hand, typedef names can be used to improve code readability. All three of the
following declarations of the signal function specify exactly the same type, the first without making use
of any typedef names.
fv *signal(int, fv *);
pfv signal(int, pfv);</pre>
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 5 If a typedef name denotes a variable length array type, the length of the array is fixed at the
time the typedef name is defined, not each time it is used:
-<!--page 137 indent 4-->
+<!--page 137 -->
<pre>
void copyt(int n)
{
<a name="6.7.8" href="#6.7.8"><h4>6.7.8 Initialization</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
initializer:
assignment-expression
[ constant-expression ]
. identifier</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
No initializer shall attempt to provide a value for an object not contained within the entity
being initialized.
-<p><!--para 3-->
+<p><!--para 3 -->
The type of the entity to be initialized shall be an array of unknown size or an object type
that is not a variable length array type.
-<p><!--para 4-->
+<p><!--para 4 -->
All the expressions in an initializer for an object that has static storage duration shall be
constant expressions or string literals.
-<p><!--para 5-->
+<p><!--para 5 -->
If the declaration of an identifier has block scope, and the identifier has external or
internal linkage, the declaration shall have no initializer for the identifier.
-<p><!--para 6-->
+<p><!--para 6 -->
If a designator has the form
<pre>
[ constant-expression ]</pre>
then the current object (defined below) shall have array type and the expression shall be
an integer constant expression. If the array is of unknown size, any nonnegative value is
valid.
-<p><!--para 7-->
+<p><!--para 7 -->
If a designator has the form
<pre>
. identifier</pre>
then the current object (defined below) shall have structure or union type and the
identifier shall be the name of a member of that type.
-<!--page 138 indent 5-->
+<!--page 138 -->
<h6>Semantics</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
An initializer specifies the initial value stored in an object.
-<p><!--para 9-->
+<p><!--para 9 -->
Except where explicitly stated otherwise, for the purposes of this subclause unnamed
members of objects of structure and union type do not participate in initialization.
Unnamed members of structure objects have indeterminate value even after initialization.
-<p><!--para 10-->
+<p><!--para 10 -->
If an object that has automatic storage duration is not initialized explicitly, its value is
indeterminate. If an object that has static storage duration is not initialized explicitly,
then:
<li> if it is a union, the first named member is initialized (recursively) according to these
rules.
</ul>
-<p><!--para 11-->
+<p><!--para 11 -->
The initializer for a scalar shall be a single expression, optionally enclosed in braces. The
initial value of the object is that of the expression (after conversion); the same type
constraints and conversions as for simple assignment apply, taking the type of the scalar
to be the unqualified version of its declared type.
-<p><!--para 12-->
+<p><!--para 12 -->
The rest of this subclause deals with initializers for objects that have aggregate or union
type.
-<p><!--para 13-->
+<p><!--para 13 -->
The initializer for a structure or union object that has automatic storage duration shall be
either an initializer list as described below, or a single expression that has compatible
structure or union type. In the latter case, the initial value of the object, including
unnamed members, is that of the expression.
-<p><!--para 14-->
+<p><!--para 14 -->
An array of character type may be initialized by a character string literal, optionally
enclosed in braces. Successive characters of the character string literal (including the
terminating null character if there is room or if the array is of unknown size) initialize the
elements of the array.
-<p><!--para 15-->
+<p><!--para 15 -->
An array with element type compatible with wchar_t may be initialized by a wide
string literal, optionally enclosed in braces. Successive wide characters of the wide string
literal (including the terminating null wide character if there is room or if the array is of
unknown size) initialize the elements of the array.
-<p><!--para 16-->
+<p><!--para 16 -->
Otherwise, the initializer for an object that has aggregate or union type shall be a brace-
enclosed list of initializers for the elements or named members.
-<p><!--para 17-->
+<p><!--para 17 -->
Each brace-enclosed initializer list has an associated current object. When no
designations are present, subobjects of the current object are initialized in order according
to the type of the current object: array elements in increasing subscript order, structure
-<!--page 139 indent 5-->
+<!--page 139 -->
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.<sup><a href="#note130"><b>130)</b></a></sup>
-<p><!--para 18-->
+<p><!--para 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.<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.
-<p><!--para 19-->
+<p><!--para 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;<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.
-<p><!--para 20-->
+<p><!--para 20 -->
If the aggregate or union contains elements or members that are aggregates or unions,
these rules apply recursively to the subaggregates or contained unions. If the initializer of
a subaggregate or contained union begins with a left brace, the initializers enclosed by
taken to account for the elements or members of the subaggregate or the first member of
the contained union; any remaining initializers are left to initialize the next element or
member of the aggregate of which the current subaggregate or contained union is a part.
-<p><!--para 21-->
+<p><!--para 21 -->
If there are fewer initializers in a brace-enclosed list than there are elements or members
of an aggregate, or fewer characters in a string literal used to initialize an array of known
size than there are elements in the array, the remainder of the aggregate shall be
initialized implicitly the same as objects that have static storage duration.
-<p><!--para 22-->
+<p><!--para 22 -->
If an array of unknown size is initialized, its size is determined by the largest indexed
element with an explicit initializer. At the end of its initializer list, the array no longer
has incomplete type.
-<!--page 140 indent 5-->
-<p><!--para 23-->
+<!--page 140 -->
+<p><!--para 23 -->
The order in which any side effects occur among the initialization list expressions is
unspecified.<sup><a href="#note133"><b>133)</b></a></sup>
-<p><!--para 24-->
+<p><!--para 24 -->
EXAMPLE 1 Provided that <a href="#7.3"><complex.h></a> has been #included, the declarations
<pre>
int i = <a href="#3.5">3.5</a>;
double complex c = 5 + 3 * I;</pre>
define and initialize i with the value 3 and c with the value 5.0 + i3.0.
-<p><!--para 25-->
+<p><!--para 25 -->
EXAMPLE 2 The declaration
<pre>
int x[] = { 1, 3, 5 };</pre>
defines and initializes x as a one-dimensional array object that has three elements, as no size was specified
and there are three initializers.
-<p><!--para 26-->
+<p><!--para 26 -->
EXAMPLE 3 The declaration
<pre>
int y[4][3] = {
The initializer for y[0] does not begin with a left brace, so three items from the list are used. Likewise the
next three are taken successively for y[1] and y[2].
-<p><!--para 27-->
+<p><!--para 27 -->
EXAMPLE 4 The declaration
<pre>
int z[4][3] = {
};</pre>
initializes the first column of z as specified and initializes the rest with zeros.
-<p><!--para 28-->
+<p><!--para 28 -->
EXAMPLE 5 The declaration
<pre>
struct { int a[3], b; } w[] = { { 1 }, 2 };</pre>
-<!--page 141 indent 5-->
-<p><!--para 29-->
+<!--page 141 -->
+<p><!--para 29 -->
EXAMPLE 6 The declaration
<pre>
short q[4][3][2] = {
}
};</pre>
in a fully bracketed form.
-<p><!--para 30-->
+<p><!--para 30 -->
Note that the fully bracketed and minimally bracketed forms of initialization are, in general, less likely to
cause confusion.
-<p><!--para 31-->
+<p><!--para 31 -->
EXAMPLE 7 One form of initialization that completes array types involves typedef names. Given the
declaration
<pre>
<pre>
int a[] = { 1, 2 }, b[] = { 3, 4, 5 };</pre>
due to the rules for incomplete types.
-<!--page 142 indent 5-->
-<p><!--para 32-->
+<!--page 142 -->
+<p><!--para 32 -->
EXAMPLE 8 The declaration
<pre>
char s[] = "abc", t[3] = "abc";</pre>
with length 4 whose elements are initialized with a character string literal. If an attempt is made to use p to
modify the contents of the array, the behavior is undefined.
-<p><!--para 33-->
+<p><!--para 33 -->
EXAMPLE 9 Arrays can be initialized to correspond to the elements of an enumeration by using
designators:
<pre>
[member_one] = "member one",
};</pre>
-<p><!--para 34-->
+<p><!--para 34 -->
EXAMPLE 10 Structure members can be initialized to nonzero values without depending on their order:
<pre>
div_t answer = { .quot = 2, .rem = -1 };</pre>
-<p><!--para 35-->
+<p><!--para 35 -->
EXAMPLE 11 Designators can be used to provide explicit initialization when unadorned initializer lists
might be misunderstood:
<pre>
struct { int a[3], b; } w[] =
{ [0].a = {1}, [1].a[0] = 2 };</pre>
-<p><!--para 36-->
+<p><!--para 36 -->
EXAMPLE 12 Space can be ''allocated'' from both ends of an array by using a single designator:
-<p><!--para 37-->
+<p><!--para 37 -->
<pre>
int a[MAX] = {
1, 3, 5, 7, 9, [MAX-5] = 8, 6, 4, 2, 0
In the above, if MAX is greater than ten, there will be some zero-valued elements in the middle; if it is less
than ten, some of the values provided by the first five initializers will be overridden by the second five.
-<p><!--para 38-->
+<p><!--para 38 -->
EXAMPLE 13 Any member of a union can be initialized:
<pre>
union { /* ... */ } u = { .any_member = 42 };</pre>
<p><b> Forward references</b>: common definitions <a href="#7.17"><stddef.h></a> (<a href="#7.17">7.17</a>).
-<!--page 143 indent 4-->
+<!--page 143 -->
<h6>footnotes</h6>
<p><small><a name="note129" href="#note129">129)</a> If the initializer list for a subaggregate or contained union does not begin with a left brace, its
<a name="6.8" href="#6.8"><h3>6.8 Statements and blocks</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
statement:
labeled-statement
iteration-statement
jump-statement</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A statement specifies an action to be performed. Except as indicated, statements are
executed in sequence.
-<p><!--para 3-->
+<p><!--para 3 -->
A block allows a set of declarations and statements to be grouped into one syntactic unit.
The initializers of objects that have automatic storage duration, and the variable length
array declarators of ordinary identifiers with block scope, are evaluated and the values are
stored in the objects (including storing an indeterminate value in objects without an
initializer) each time the declaration is reached in the order of execution, as if it were a
statement, and within each declaration in the order that declarators appear.
-<p><!--para 4-->
+<p><!--para 4 -->
A full expression is an expression that is not part of another expression or of a declarator.
Each of the following is a full expression: an initializer; the expression in an expression
statement; the controlling expression of a selection statement (if or switch); the
<a name="6.8.1" href="#6.8.1"><h4>6.8.1 Labeled statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
labeled-statement:
identifier : statement
case constant-expression : statement
default : statement</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A case or default label shall appear only in a switch statement. Further
constraints on such labels are discussed under the switch statement.
-<!--page 144 indent 4-->
-<p><!--para 3-->
+<!--page 144 -->
+<p><!--para 3 -->
Label names shall be unique within a function.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
Any statement may be preceded by a prefix that declares an identifier as a label name.
Labels in themselves do not alter the flow of control, which continues unimpeded across
them.
<a name="6.8.2" href="#6.8.2"><h4>6.8.2 Compound statement</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
compound-statement:
{ block-item-listopt }
declaration
statement</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A compound statement is a block.
<a name="6.8.3" href="#6.8.3"><h4>6.8.3 Expression and null statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
expression-statement:
expressionopt ;</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The expression in an expression statement is evaluated as a void expression for its side
effects.<sup><a href="#note134"><b>134)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
A null statement (consisting of just a semicolon) performs no operations.
-<p><!--para 4-->
+<p><!--para 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
a cast:
-<!--page 145 indent 4-->
-<p><!--para 5-->
+<!--page 145 -->
+<p><!--para 5 -->
EXAMPLE 2 In the program fragment
<pre>
char *s;
;</pre>
a null statement is used to supply an empty loop body to the iteration statement.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 3 A null statement may also be used to carry a label just before the closing } of a compound
statement.
<pre>
<a name="6.8.4" href="#6.8.4"><h4>6.8.4 Selection statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
selection-statement:
if ( expression ) statement
if ( expression ) statement else statement
switch ( expression ) statement</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A selection statement selects among a set of statements depending on the value of a
controlling expression.
-<p><!--para 3-->
+<p><!--para 3 -->
A selection statement is a block whose scope is a strict subset of the scope of its
enclosing block. Each associated substatement is also a block whose scope is a strict
subset of the scope of the selection statement.
<a name="6.8.4.1" href="#6.8.4.1"><h5>6.8.4.1 The if statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The controlling expression of an if statement shall have scalar type.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
In both forms, the first substatement is executed if the expression compares unequal to 0.
In the else form, the second substatement is executed if the expression compares equal
-<!--page 146 indent 4-->
+<!--page 146 -->
to 0. If the first substatement is reached via a label, the second substatement is not
executed.
-<p><!--para 3-->
+<p><!--para 3 -->
An else is associated with the lexically nearest preceding if that is allowed by the
syntax.
<a name="6.8.4.2" href="#6.8.4.2"><h5>6.8.4.2 The switch statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The controlling expression of a switch statement shall have integer type.
-<p><!--para 2-->
+<p><!--para 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.<sup><a href="#note135"><b>135)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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.
expressions with values that duplicate case constant expressions in the enclosing
switch statement.)
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
A switch statement causes control to jump to, into, or past the statement that is the
switch body, depending on the value of a controlling expression, and on the presence of a
default label and the values of any case labels on or in the switch body. A case or
default label is accessible only within the closest enclosing switch statement.
-<p><!--para 5-->
+<p><!--para 5 -->
The integer promotions are performed on the controlling expression. The constant
expression in each case label is converted to the promoted type of the controlling
expression. If a converted value matches that of the promoted controlling expression,
expression matches and there is no default label, no part of the switch body is
executed.
Implementation limits
-<p><!--para 6-->
+<p><!--para 6 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, the implementation may limit the number of case values in a
switch statement.
-<!--page 147 indent 4-->
-<p><!--para 7-->
+<!--page 147 -->
+<p><!--para 7 -->
EXAMPLE In the artificial program fragment
<pre>
switch (expr)
<a name="6.8.5" href="#6.8.5"><h4>6.8.5 Iteration statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
iteration-statement:
while ( expression ) statement
for ( expressionopt ; expressionopt ; expressionopt ) statement
for ( declaration expressionopt ; expressionopt ) statement</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The controlling expression of an iteration statement shall have scalar type.
-<p><!--para 3-->
+<p><!--para 3 -->
The declaration part of a for statement shall only declare identifiers for objects having
storage class auto or register.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
An iteration statement causes a statement called the loop body to be executed repeatedly
until the controlling expression compares equal to 0. The repetition occurs regardless of
whether the loop body is entered from the iteration statement or by a jump.<sup><a href="#note136"><b>136)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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.
-<!--page 148 indent 4-->
+<!--page 148 -->
<h6>footnotes</h6>
<p><small><a name="note136" href="#note136">136)</a> Code jumped over is not executed. In particular, the controlling expression of a for or while
</small>
<a name="6.8.5.1" href="#6.8.5.1"><h5>6.8.5.1 The while statement</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The evaluation of the controlling expression takes place before each execution of the loop
body.
<a name="6.8.5.2" href="#6.8.5.2"><h5>6.8.5.2 The do statement</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The evaluation of the controlling expression takes place after each execution of the loop
body.
<a name="6.8.5.3" href="#6.8.5.3"><h5>6.8.5.3 The for statement</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The statement
<pre>
for ( clause-1 ; expression-2 ; expression-3 ) statement</pre>
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.<sup><a href="#note137"><b>137)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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"><h4>6.8.6 Jump statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
jump-statement:
goto identifier ;
break ;
return expressionopt ;</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A jump statement causes an unconditional jump to another place.
-<!--page 149 indent 4-->
+<!--page 149 -->
<a name="6.8.6.1" href="#6.8.6.1"><h5>6.8.6.1 The goto statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The identifier in a goto statement shall name a label located somewhere in the enclosing
function. A goto statement shall not jump from outside the scope of an identifier having
a variably modified type to inside the scope of that identifier.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A goto statement causes an unconditional jump to the statement prefixed by the named
label in the enclosing function.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE 1 It is sometimes convenient to jump into the middle of a complicated set of statements. The
following outline presents one possible approach to a problem based on these three assumptions:
<ol>
// handle other operations
/* ... */</pre>
}
-<!--page 150 indent 4-->
+<!--page 150 -->
</ol>
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE 2 A goto statement is not allowed to jump past any declarations of objects with variably
modified types. A jump within the scope, however, is permitted.
<pre>
<a name="6.8.6.2" href="#6.8.6.2"><h5>6.8.6.2 The continue statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A continue statement shall appear only in or as a loop body.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A continue statement causes a jump to the loop-continuation portion of the smallest
enclosing iteration statement; that is, to the end of the loop body. More precisely, in each
of the statements
<a name="6.8.6.3" href="#6.8.6.3"><h5>6.8.6.3 The break statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A break statement shall appear only in or as a switch body or loop body.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A break statement terminates execution of the smallest enclosing switch or iteration
statement.
-<!--page 151 indent 4-->
+<!--page 151 -->
<a name="6.8.6.4" href="#6.8.6.4"><h5>6.8.6.4 The return statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A return statement with an expression shall not appear in a function whose return type
is void. A return statement without an expression shall only appear in a function
whose return type is void.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A return statement terminates execution of the current function and returns control to
its caller. A function may have any number of return statements.
-<p><!--para 3-->
+<p><!--para 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.<sup><a href="#note139"><b>139)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE In:
<pre>
struct s { double i; } f(void);
-<!--page 152 indent 4-->
+<!--page 152 -->
<h6>footnotes</h6>
<p><small><a name="note139" href="#note139">139)</a> The return statement is not an assignment. The overlap restriction of subclause <a href="#6.5.16.1">6.5.16.1</a> does not
<a name="6.9" href="#6.9"><h3>6.9 External definitions</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
translation-unit:
external-declaration
function-definition
declaration</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The storage-class specifiers auto and register shall not appear in the declaration
specifiers in an external declaration.
-<p><!--para 3-->
+<p><!--para 3 -->
There shall be no more than one external definition for each identifier declared with
internal linkage in a translation unit. Moreover, if an identifier declared with internal
linkage is used in an expression (other than as a part of the operand of a sizeof
operator whose result is an integer constant), there shall be exactly one external definition
for the identifier in the translation unit.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
As discussed in <a href="#5.1.1.1">5.1.1.1</a>, the unit of program text after preprocessing is a translation unit,
which consists of a sequence of external declarations. These are described as ''external''
because they appear outside any function (and hence have file scope). As discussed in
<a href="#6.7">6.7</a>, a declaration that also causes storage to be reserved for an object or a function named
by the identifier is a definition.
-<p><!--para 5-->
+<p><!--para 5 -->
An external definition is an external declaration that is also a definition of a function
(other than an inline definition) or an object. If an identifier declared with external
linkage is used in an expression (other than as part of the operand of a sizeof operator
-<!--page 153 indent 4-->
+<!--page 153 -->
<h6>footnotes</h6>
<p><small><a name="note140" href="#note140">140)</a> Thus, if an identifier declared with external linkage is not used in an expression, there need be no
<a name="6.9.1" href="#6.9.1"><h4>6.9.1 Function definitions</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
function-definition:
declaration-specifiers declarator declaration-listopt compound-statement
declaration
declaration-list declaration</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The identifier declared in a function definition (which is the name of the function) shall
have a function type, as specified by the declarator portion of the function definition.<sup><a href="#note141"><b>141)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The return type of a function shall be void or an object type other than array type.
-<p><!--para 4-->
+<p><!--para 4 -->
The storage-class specifier, if any, in the declaration specifiers shall be either extern or
static.
-<p><!--para 5-->
+<p><!--para 5 -->
If the declarator includes a parameter type list, the declaration of each parameter shall
include an identifier, except for the special case of a parameter list consisting of a single
parameter of type void, in which case there shall not be an identifier. No declaration list
shall follow.
-<p><!--para 6-->
+<p><!--para 6 -->
If the declarator includes an identifier list, each declaration in the declaration list shall
have at least one declarator, those declarators shall declare only identifiers from the
identifier list, and every identifier in the identifier list shall be declared. An identifier
-<!--page 154 indent 5-->
+<!--page 154 -->
<h6>Semantics</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The declarator in a function definition specifies the name of the function being defined
and the identifiers of its parameters. If the declarator includes a parameter type list, the
list also specifies the types of all the parameters; such a declarator also serves as 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.
-<p><!--para 8-->
+<p><!--para 8 -->
If a function that accepts a variable number of arguments is defined without a parameter
type list that ends with the ellipsis notation, the behavior is undefined.
-<p><!--para 9-->
+<p><!--para 9 -->
Each parameter has automatic storage duration. Its identifier is an lvalue, which is in
effect declared at the head of the compound statement that constitutes the function body
(and therefore cannot be redeclared in the function body except in an enclosed block).
The layout of the storage for parameters is unspecified.
-<p><!--para 10-->
+<p><!--para 10 -->
On entry to the function, the size expressions of each variably modified parameter are
evaluated and the value of each argument expression is converted to the type of the
corresponding parameter as if by assignment. (Array expressions and function
designators as arguments were converted to pointers before the call.)
-<p><!--para 11-->
+<p><!--para 11 -->
After all parameters have been assigned, the compound statement that constitutes the
body of the function definition is executed.
-<p><!--para 12-->
+<p><!--para 12 -->
If the } that terminates a function is reached, and the value of the function call is used by
the caller, the behavior is undefined.
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 1 In the following:
<pre>
extern int max(int a, int b)
-<!--page 155 indent 5-->
+<!--page 155 -->
<pre>
extern int max(a, b)
int a, b;
that the first form acts as a prototype declaration that forces conversion of the arguments of subsequent calls
to the function, whereas the second form does not.
-<p><!--para 14-->
+<p><!--para 14 -->
EXAMPLE 2 To pass one function to another, one might say
<pre>
int f(void);
<a name="6.9.2" href="#6.9.2"><h4>6.9.2 External object definitions</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
If the declaration of an identifier for an object has file scope and an initializer, the
declaration is an external definition for the identifier.
-<p><!--para 2-->
+<p><!--para 2 -->
A declaration of an identifier for an object that has file scope without an initializer, and
without a storage-class specifier or with the storage-class specifier static, constitutes a
tentative definition. If a translation unit contains one or more tentative definitions for an
the behavior is exactly as if the translation unit contains a file scope declaration of that
identifier, with the composite type as of the end of the translation unit, with an initializer
equal to 0.
-<p><!--para 3-->
+<p><!--para 3 -->
If the declaration of an identifier for an object is a tentative definition and has internal
linkage, the declared type shall not be an incomplete type.
-<!--page 156 indent 4-->
-<p><!--para 4-->
+<!--page 156 -->
+<p><!--para 4 -->
EXAMPLE 1
<pre>
int i1 = 1; // definition, external linkage
extern int i4; // refers to previous, whose linkage is external
extern int i5; // refers to previous, whose linkage is internal</pre>
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 2 If at the end of the translation unit containing
<pre>
int i[];</pre>
the array i still has incomplete type, the implicit initializer causes it to have one element, which is set to
zero on program startup.
-<!--page 157 indent 4-->
+<!--page 157 -->
<a name="6.10" href="#6.10"><h3>6.10 Preprocessing directives</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 158 indent 4-->
+<p><!--para 1 -->
+<!--page 158 -->
<pre>
preprocessing-file:
groupopt
new-line:
the new-line character</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the
following constraints: The first token in the sequence is a # preprocessing token that (at
the start of translation phase 4) is either the first character in the source file (optionally
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
-<!--page 159 indent 4-->
+<!--page 159 -->
invocation of a function-like macro.
-<p><!--para 3-->
+<p><!--para 3 -->
A text line shall not begin with a # preprocessing token. A non-directive shall not begin
with any of the directive names appearing in the syntax.
-<p><!--para 4-->
+<p><!--para 4 -->
When in a group that is skipped (<a href="#6.10.1">6.10.1</a>), the directive syntax is relaxed to allow any
sequence of preprocessing tokens to occur between the directive name and the following
new-line character.
<h6>Constraints</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The only white-space characters that shall appear between preprocessing tokens within a
preprocessing directive (from just after the introducing # preprocessing token through
just before the terminating new-line character) are space and horizontal-tab (including
spaces that have replaced comments or possibly other white-space characters in
translation phase 3).
<h6>Semantics</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The implementation can process and skip sections of source files conditionally, include
other source files, and replace macros. These capabilities are called preprocessing,
because conceptually they occur before translation of the resulting translation unit.
-<p><!--para 7-->
+<p><!--para 7 -->
The preprocessing tokens within a preprocessing directive are not subject to macro
expansion unless otherwise stated.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE In:
<pre>
#define EMPTY
<a name="6.10.1" href="#6.10.1"><h4>6.10.1 Conditional inclusion</h4></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The expression that controls conditional inclusion shall be an integer constant expression
except that: it shall not contain a cast; identifiers (including those lexically identical to
keywords) are interpreted as described below;<sup><a href="#note144"><b>144)</b></a></sup> and it may contain unary operator
-<!--page 160 indent 4-->
+<!--page 160 -->
<pre>
defined identifier</pre>
or
which evaluate to 1 if the identifier is currently defined as a macro name (that is, if it is
predefined or if it has been the subject of a #define preprocessing directive without an
intervening #undef directive with the same subject identifier), 0 if it is not.
-<p><!--para 2-->
+<p><!--para 2 -->
Each preprocessing token that remains (in the list of preprocessing tokens that will
become the controlling expression) after all macro replacements have occurred shall be in
the lexical form of a token (<a href="#6.4">6.4</a>).
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Preprocessing directives of the forms
<pre>
# if constant-expression new-line groupopt
# elif constant-expression new-line groupopt</pre>
check whether the controlling constant expression evaluates to nonzero.
-<p><!--para 4-->
+<p><!--para 4 -->
Prior to evaluation, macro invocations in the list of preprocessing tokens that will become
the controlling constant expression are replaced (except for those macro names modified
by the defined unary operator), just as in normal text. If the token defined is
the value obtained when an identical character constant occurs in an expression (other
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.
-<p><!--para 5-->
+<p><!--para 5 -->
Preprocessing directives of the forms
-<!--page 161 indent 4-->
+<!--page 161 -->
<pre>
# ifdef identifier new-line groupopt
# ifndef identifier new-line groupopt</pre>
check whether the identifier is or is not currently defined as a macro name. Their
conditions are equivalent to #if defined identifier and #if !defined identifier
respectively.
-<p><!--para 6-->
+<p><!--para 6 -->
Each directive's condition is checked in order. If it evaluates to false (zero), the group
that it controls is skipped: directives are processed only through the name that determines
the directive in order to keep track of the level of nested conditionals; the rest of the
<a name="6.10.2" href="#6.10.2"><h4>6.10.2 Source file inclusion</h4></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A #include directive shall identify a header or source file that can be processed by the
implementation.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A preprocessing directive of the form
<pre>
# include <h-char-sequence> new-line</pre>
the specified sequence between the < and > delimiters, and causes the replacement of that
directive by the entire contents of the header. How the places are specified or the header
identified is implementation-defined.
-<p><!--para 3-->
+<p><!--para 3 -->
A preprocessing directive of the form
-<!--page 162 indent 4-->
+<!--page 162 -->
<pre>
# include "q-char-sequence" new-line</pre>
causes the replacement of that directive by the entire contents of the source file identified
# include <h-char-sequence> new-line</pre>
with the identical contained sequence (including > characters, if any) from the original
directive.
-<p><!--para 4-->
+<p><!--para 4 -->
A preprocessing directive of the form
<pre>
# include pp-tokens new-line</pre>
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.
-<p><!--para 5-->
+<p><!--para 5 -->
The implementation shall provide unique mappings for sequences consisting of one or
more nondigits or digits (<a href="#6.4.2.1">6.4.2.1</a>) followed by a period (.) and a single nondigit. The
first character shall not be a digit. The implementation may ignore distinctions of
alphabetical case and restrict the mapping to eight significant characters before the
period.
-<p><!--para 6-->
+<p><!--para 6 -->
A #include preprocessing directive may appear in a source file that has been read
because of a #include directive in another file, up to an implementation-defined
nesting limit (see <a href="#5.2.4.1">5.2.4.1</a>).
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1 The most common uses of #include preprocessing directives are as in the following:
<pre>
#include <a href="#7.19"><stdio.h></a>
#include "myprog.h"</pre>
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 2 This illustrates macro-replaced #include directives:
-<!--page 163 indent 4-->
+<!--page 163 -->
<pre>
#if VERSION == 1
#define INCFILE "vers1.h"
<a name="6.10.3" href="#6.10.3"><h4>6.10.3 Macro replacement</h4></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
Two replacement lists are identical if and only if the preprocessing tokens in both have
the same number, ordering, spelling, and white-space separation, where all white-space
separations are considered identical.
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier currently defined as an object-like macro shall not be redefined by another
#define preprocessing directive unless the second definition is an object-like macro
definition and the two replacement lists are identical. Likewise, an identifier currently
preprocessing directive unless the second definition is a function-like macro definition
that has the same number and spelling of parameters, and the two replacement lists are
identical.
-<p><!--para 3-->
+<p><!--para 3 -->
There shall be white-space between the identifier and the replacement list in the definition
of an object-like macro.
-<p><!--para 4-->
+<p><!--para 4 -->
If the identifier-list in the macro definition does not end with an ellipsis, the number of
arguments (including those arguments consisting of no preprocessing tokens) in an
invocation of a function-like macro shall equal the number of parameters in the macro
definition. Otherwise, there shall be more arguments in the invocation than there are
parameters in the macro definition (excluding the ...). There shall exist a )
preprocessing token that terminates the invocation.
-<p><!--para 5-->
+<p><!--para 5 -->
The identifier __VA_ARGS__ shall occur only in the replacement-list of a function-like
macro that uses the ellipsis notation in the parameters.
-<p><!--para 6-->
+<p><!--para 6 -->
A parameter identifier in a function-like macro shall be uniquely declared within its
scope.
<h6>Semantics</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The identifier immediately following the define is called the macro name. There is one
name space for macro names. Any white-space characters preceding or following the
replacement list of preprocessing tokens are not considered part of the replacement list
for either form of macro.
-<!--page 164 indent 5-->
-<p><!--para 8-->
+<!--page 164 -->
+<p><!--para 8 -->
If a # preprocessing token, followed by an identifier, occurs lexically at the point at which
a preprocessing directive could begin, the identifier is not subject to macro replacement.
-<p><!--para 9-->
+<p><!--para 9 -->
A preprocessing directive of the form
<pre>
# define identifier replacement-list new-line</pre>
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.
-<p><!--para 10-->
+<p><!--para 10 -->
A preprocessing directive of the form
<pre>
# define identifier lparen identifier-listopt ) replacement-list new-line
left and right parenthesis preprocessing tokens. Within the sequence of preprocessing
tokens making up an invocation of a function-like macro, new-line is considered a normal
white-space character.
-<p><!--para 11-->
+<p><!--para 11 -->
The sequence of preprocessing tokens bounded by the outside-most matching parentheses
forms the list of arguments for the function-like macro. The individual arguments within
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,<sup><a href="#note150"><b>150)</b></a></sup> the behavior is undefined.
-<p><!--para 12-->
+<p><!--para 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
-<!--page 165 indent 4-->
+<!--page 165 -->
merger, the number of arguments is one more than the number of parameters in the macro
definition (excluding the ...).
</small>
<a name="6.10.3.1" href="#6.10.3.1"><h5>6.10.3.1 Argument substitution</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
After the arguments for the invocation of a function-like macro have been identified,
argument substitution takes place. A parameter in the replacement list, unless preceded
by a # or ## preprocessing token or followed by a ## preprocessing token (see below), is
expanded. Before being substituted, each argument's preprocessing tokens are
completely macro replaced as if they formed the rest of the preprocessing file; no other
preprocessing tokens are available.
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier __VA_ARGS__ that occurs in the replacement list shall be treated as if it
were a parameter, and the variable arguments shall form the preprocessing tokens used to
replace it.
<a name="6.10.3.2" href="#6.10.3.2"><h5>6.10.3.2 The # operator</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
Each # preprocessing token in the replacement list for a function-like macro shall be
followed by a parameter as the next preprocessing token in the replacement list.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If, in the replacement list, a parameter is immediately preceded by a # preprocessing
token, both are replaced by a single character string literal preprocessing token that
contains the spelling of the preprocessing token sequence for the corresponding
results is not a valid character string literal, the behavior is undefined. The character
string literal corresponding to an empty argument is "". The order of evaluation of # and
## operators is unspecified.
-<!--page 166 indent 4-->
+<!--page 166 -->
<a name="6.10.3.3" href="#6.10.3.3"><h5>6.10.3.3 The ## operator</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A ## preprocessing token shall not occur at the beginning or at the end of a replacement
list for either form of macro definition.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If, in the replacement list of a function-like macro, a parameter is immediately preceded
or followed by a ## preprocessing token, the parameter is replaced by the corresponding
argument's preprocessing token sequence; however, if an argument consists of no
preprocessing tokens, the parameter is replaced by a placemarker preprocessing token
instead.<sup><a href="#note151"><b>151)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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
If the result is not a valid preprocessing token, the behavior is undefined. The resulting
token is available for further macro replacement. The order of evaluation of ## operators
is unspecified.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE In the following fragment:
<pre>
#define hash_hash # ## #
this new token is not the ## operator.
-<!--page 167 indent 4-->
+<!--page 167 -->
<h6>footnotes</h6>
<p><small><a name="note151" href="#note151">151)</a> Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that
</small>
<a name="6.10.3.4" href="#6.10.3.4"><h5>6.10.3.4 Rescanning and further replacement</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
After all parameters in the replacement list have been substituted and # and ##
processing has taken place, all placemarker preprocessing tokens are removed. Then, the
resulting preprocessing token sequence is rescanned, along with all subsequent
preprocessing tokens of the source file, for more macro names to replace.
-<p><!--para 2-->
+<p><!--para 2 -->
If the name of the macro being replaced is found during this scan of the replacement list
(not including the rest of the source file's preprocessing tokens), it is not replaced.
Furthermore, if any nested replacements encounter the name of the macro being replaced,
it is not replaced. These nonreplaced macro name preprocessing tokens are no longer
available for further replacement even if they are later (re)examined in contexts in which
that macro name preprocessing token would otherwise have been replaced.
-<p><!--para 3-->
+<p><!--para 3 -->
The resulting completely macro-replaced preprocessing token sequence is not processed
as a preprocessing directive even if it resembles one, but all pragma unary operator
expressions within it are then processed as specified in <a href="#6.10.9">6.10.9</a> below.
<a name="6.10.3.5" href="#6.10.3.5"><h5>6.10.3.5 Scope of macro definitions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A macro definition lasts (independent of block structure) until a corresponding #undef
directive is encountered or (if none is encountered) until the end of the preprocessing
translation unit. Macro definitions have no significance after translation phase 4.
-<p><!--para 2-->
+<p><!--para 2 -->
A preprocessing directive of the form
<pre>
# undef identifier new-line</pre>
causes the specified identifier no longer to be defined as a macro name. It is ignored if
the specified identifier is not currently defined as a macro name.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE 1 The simplest use of this facility is to define a ''manifest constant'', as in
<pre>
#define TABSIZE 100
int table[TABSIZE];</pre>
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE 2 The following defines a function-like macro whose value is the maximum of its arguments.
It has the advantages of working for any compatible types of the arguments and of generating in-line code
without the overhead of function calling. It has the disadvantages of evaluating one or the other of its
<pre>
#define max(a, b) ((a) > (b) ? (a) : (b))</pre>
The parentheses ensure that the arguments and the resulting expression are bound properly.
-<!--page 168 indent 4-->
-<p><!--para 5-->
+<!--page 168 -->
+<p><!--para 5 -->
EXAMPLE 3 To illustrate the rules for redefinition and reexamination, the sequence
<pre>
#define x 3
int i[] = { 1, 23, 4, 5, };
char c[2][6] = { "hello", "" };</pre>
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 4 To illustrate the rules for creating character string literals and concatenating tokens, the
sequence
<pre>
glue(HIGH, LOW);
xglue(HIGH, LOW)</pre>
results in
-<!--page 169 indent 4-->
+<!--page 169 -->
<pre>
printf("x" "1" "= %d, x" "2" "= %s", x1, x2);
fputs(
"hello, world"</pre>
Space around the # and ## tokens in the macro definition is optional.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 5 To illustrate the rules for placemarker preprocessing tokens, the sequence
<pre>
#define t(x,y,z) x ## y ## z
int j[] = { 123, 45, 67, 89,
10, 11, 12, };</pre>
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 6 To demonstrate the redefinition rules, the following sequence is valid.
<pre>
#define OBJ_LIKE (1-1)
#define FUNC_LIKE(b) ( a ) // different parameter usage
#define FUNC_LIKE(b) ( b ) // different parameter spelling</pre>
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 7 Finally, to show the variable argument list macro facilities:
-<!--page 170 indent 4-->
+<!--page 170 -->
<pre>
#define debug(...) fprintf(stderr, __VA_ARGS__)
#define showlist(...) puts(#__VA_ARGS__)
<a name="6.10.4" href="#6.10.4"><h4>6.10.4 Line control</h4></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The string literal of a #line directive, if present, shall be a character string literal.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The line number of the current source line is one greater than the number of new-line
characters read or introduced in translation phase 1 (<a href="#5.1.1.2">5.1.1.2</a>) while processing the source
file to the current token.
-<p><!--para 3-->
+<p><!--para 3 -->
A preprocessing directive of the form
<pre>
# line digit-sequence new-line</pre>
with a source line that has a line number as specified by the digit sequence (interpreted as
a decimal integer). The digit sequence shall not specify zero, nor a number greater than
2147483647.
-<p><!--para 4-->
+<p><!--para 4 -->
A preprocessing directive of the form
<pre>
# line digit-sequence "s-char-sequenceopt" new-line</pre>
sets the presumed line number similarly and changes the presumed name of the source
file to be the contents of the character string literal.
-<p><!--para 5-->
+<p><!--para 5 -->
A preprocessing directive of the form
<pre>
# line pp-tokens new-line</pre>
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 and is then processed as appropriate.
-<!--page 171 indent 4-->
+<!--page 171 -->
<a name="6.10.5" href="#6.10.5"><h4>6.10.5 Error directive</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A preprocessing directive of the form
<pre>
# error pp-tokensopt new-line</pre>
<a name="6.10.6" href="#6.10.6"><h4>6.10.6 Pragma directive</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A preprocessing directive of the form
<pre>
# pragma pp-tokensopt new-line</pre>
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.
-<p><!--para 2-->
+<p><!--para 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 forms<sup><a href="#note153"><b>153)</b></a></sup> whose meanings are described
-<!--page 172 indent 4-->
+<!--page 172 -->
<h6>footnotes</h6>
<p><small><a name="note152" href="#note152">152)</a> An implementation is not required to perform macro replacement in pragmas, but it is permitted
<a name="6.10.7" href="#6.10.7"><h4>6.10.7 Null directive</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A preprocessing directive of the form
<pre>
# new-line</pre>
has no effect.
<a name="6.10.8" href="#6.10.8"><h4>6.10.8 Predefined macro names</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following macro names<sup><a href="#note154"><b>154)</b></a></sup> shall be defined by the implementation:
__DATE__ The date of translation of the preprocessing translation unit: a character
<pre>
-<!--page 173 indent 4-->
-<p><!--para 2-->
+<!--page 173 -->
+<p><!--para 2 -->
The following macro names are conditionally defined by the implementation:
__STDC_IEC_559__ The integer constant 1, intended to indicate conformance to the
<pre>
adherence to the specifications in informative <a href="#G">annex G</a> (IEC 60559
compatible complex arithmetic).</pre>
__STDC_ISO_10646__ An integer constant of the form yyyymmL (for example,
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
199712L). If this symbol is defined, then every character in the Unicode
required set, when stored in an object of type wchar_t, has the same
month.</pre>
The values of the predefined macros (except for __FILE__ and __LINE__) remain
constant throughout the translation unit.
-<p><!--para 4-->
+<p><!--para 4 -->
None of these macro names, nor the identifier defined, shall be the subject of a
#define or a #undef preprocessing directive. Any other predefined macro names
shall begin with a leading underscore followed by an uppercase letter or a second
underscore.
-<p><!--para 5-->
+<p><!--para 5 -->
The implementation shall not predefine the macro __cplusplus, nor shall it define it
in any standard header.
<p><b> Forward references</b>: the asctime function (<a href="#7.23.3.1">7.23.3.1</a>), standard headers (<a href="#7.1.2">7.1.2</a>).
<a name="6.10.9" href="#6.10.9"><h4>6.10.9 Pragma operator</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A unary operator expression of the form:
<pre>
_Pragma ( string-literal )</pre>
preprocessing tokens that are executed as if they were the pp-tokens in a pragma
directive. The original four preprocessing tokens in the unary operator expression are
removed.
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE A directive of the form:
<pre>
#pragma listing on "..\listing.dir"</pre>
can also be expressed as:
-<!--page 174 indent 0-->
+<!--page 174 -->
<pre>
_Pragma ( "listing on \"..\\listing.dir\"" )</pre>
The latter form is processed in the same way whether it appears literally as shown, or results from macro
replacement, as in:
-<!--page 175 indent 4-->
+<!--page 175 -->
<pre>
#define LISTING(x) PRAGMA(listing on #x)
#define PRAGMA(x) _Pragma(#x)
<a name="6.11" href="#6.11"><h3>6.11 Future language directions</h3></a>
<a name="6.11.1" href="#6.11.1"><h4>6.11.1 Floating types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Future standardization may include additional floating-point types, including those with
greater range, precision, or both than long double.
<a name="6.11.2" href="#6.11.2"><h4>6.11.2 Linkages of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Declaring an identifier with internal linkage at file scope without the static storage-
class specifier is an obsolescent feature.
<a name="6.11.3" href="#6.11.3"><h4>6.11.3 External names</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Restriction of the significance of an external name to fewer than 255 characters
(considering each universal character name or extended source character as a single
character) is an obsolescent feature that is a concession to existing implementations.
<a name="6.11.4" href="#6.11.4"><h4>6.11.4 Character escape sequences</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Lowercase letters as escape sequences are reserved for future standardization. Other
characters may be used in extensions.
<a name="6.11.5" href="#6.11.5"><h4>6.11.5 Storage-class specifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The placement of a storage-class specifier other than at the beginning of the declaration
specifiers in a declaration is an obsolescent feature.
<a name="6.11.6" href="#6.11.6"><h4>6.11.6 Function declarators</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The use of function declarators with empty parentheses (not prototype-format parameter
type declarators) is an obsolescent feature.
<a name="6.11.7" href="#6.11.7"><h4>6.11.7 Function definitions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The use of function definitions with separate parameter identifier and declaration lists
(not prototype-format parameter type and identifier declarators) is an obsolescent feature.
<a name="6.11.8" href="#6.11.8"><h4>6.11.8 Pragma directives</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Pragmas whose first preprocessing token is STDC are reserved for future standardization.
<a name="6.11.9" href="#6.11.9"><h4>6.11.9 Predefined macro names</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macro names beginning with __STDC_ are reserved for future standardization.
-<!--page 176 indent 4-->
+<!--page 176 -->
<a name="7" href="#7"><h2>7. Library</h2></a>
<a name="7.1" href="#7.1"><h3>7.1 Introduction</h3></a>
<a name="7.1.1" href="#7.1.1"><h4>7.1.1 Definitions of terms</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A string is a contiguous sequence of characters terminated by and including the first null
character. The term multibyte string is sometimes used instead to emphasize special
processing given to multibyte characters contained in the string or to avoid confusion
with a wide string. A pointer to a string is a pointer to its initial (lowest addressed)
character. The length of a string is the number of bytes preceding the null character and
the value of a string is the sequence of the values of the contained characters, in order.
-<p><!--para 2-->
+<p><!--para 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.<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.
-<p><!--para 3-->
+<p><!--para 3 -->
A null wide character is a wide character with code value zero.
-<p><!--para 4-->
+<p><!--para 4 -->
A wide string is a contiguous sequence of wide characters terminated by and including
the first null wide character. A pointer to a wide string is a pointer to its initial (lowest
addressed) wide character. The length of a wide string is the number of wide characters
preceding the null wide character and the value of a wide string is the sequence of code
values of the contained wide characters, in order.
-<p><!--para 5-->
+<p><!--para 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
-<!--page 177 indent 4-->
+<!--page 177 -->
<h6>footnotes</h6>
<p><small><a name="note157" href="#note157">157)</a> The functions that make use of the decimal-point character are the numeric conversion functions
</small>
<a name="7.1.2" href="#7.1.2"><h4>7.1.2 Standard headers</h4></a>
-<p><!--para 1-->
+<p><!--para 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
include type qualifiers, unless explicitly stated otherwise.
-<p><!--para 2-->
+<p><!--para 2 -->
The standard headers are
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
<a href="#7.2"><assert.h></a> <a href="#7.8"><inttypes.h></a> <a href="#7.14"><signal.h></a> <a href="#7.20"><stdlib.h></a>
<a href="#7.3"><complex.h></a> <a href="#7.9"><iso646.h></a> <a href="#7.15"><stdarg.h></a> <a href="#7.21"><string.h></a>
If a file with the same name as one of the above < and > delimited sequences, not
provided as part of the implementation, is placed in any of the standard places that are
searched for included source files, the behavior is undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
Standard headers may be included in any order; each may be included more than once in
a given scope, with no effect different from being included only once, except that the
effect of including <a href="#7.2"><assert.h></a> depends on the definition of NDEBUG (see <a href="#7.2">7.2</a>). If
included after the initial reference to the identifier. The program shall not have any
macros with names lexically identical to keywords currently defined prior to the
inclusion.
-<p><!--para 5-->
+<p><!--para 5 -->
Any definition of an object-like macro described in this clause shall expand to code that is
fully protected by parentheses where necessary, so that it groups in an arbitrary
expression as if it were a single identifier.
-<p><!--para 6-->
+<p><!--para 6 -->
Any declaration of a library function shall have external linkage.
-<p><!--para 7-->
+<p><!--para 7 -->
A summary of the contents of the standard headers is given in <a href="#B">annex B</a>.
<p><b> Forward references</b>: diagnostics (<a href="#7.2">7.2</a>).
-<!--page 178 indent 4-->
+<!--page 178 -->
<h6>footnotes</h6>
<p><small><a name="note159" href="#note159">159)</a> A header is not necessarily a source file, nor are the < and > delimited sequences in header names
</small>
<a name="7.1.3" href="#7.1.3"><h4>7.1.3 Reserved identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Each header declares or defines all identifiers listed in its associated subclause, and
optionally declares or defines identifiers listed in its associated future library directions
subclause and identifiers which are always reserved either for any use or for use as file
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.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
No other identifiers are reserved. If the program declares or defines an identifier in a
context in which it is reserved (other than as allowed by <a href="#7.1.4">7.1.4</a>), or defines a reserved
identifier as a macro name, the behavior is undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
If the program removes (with #undef) any macro definition of an identifier in the first
group listed above, the behavior is undefined.
</small>
<a name="7.1.4" href="#7.1.4"><h4>7.1.4 Use of library functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Each of the following statements applies unless explicitly stated otherwise in the detailed
descriptions that follow: If an argument to a function has an invalid value (such as a value
outside the domain of the function, or a pointer outside the address space of the program,
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
-<!--page 179 indent 4-->
+<!--page 179 -->
the header, so if a library function is declared explicitly when its header is included, one
of the techniques shown below can be used to ensure the declaration is not affected by
such a macro. Any macro definition of a function can be suppressed locally by enclosing
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.
-<p><!--para 2-->
+<p><!--para 2 -->
Provided that a library function can be declared without reference to any type defined in a
header, it is also permissible to declare the function and use it without including its
associated header.
-<p><!--para 3-->
+<p><!--para 3 -->
There is a sequence point immediately before a library function returns.
-<p><!--para 4-->
+<p><!--para 4 -->
The functions in the standard library are not guaranteed to be reentrant and may modify
objects with static storage duration.<sup><a href="#note164"><b>164)</b></a></sup>
-<!--page 180 indent 4-->
-<p><!--para 5-->
+<!--page 180 -->
+<p><!--para 5 -->
EXAMPLE The function atoi may be used in any of several ways:
<ul>
<li> by use of its associated header (possibly generating a macro expansion)
/* ... */
i = (atoi)(str);</pre>
<li> by explicit declaration
-<!--page 181 indent 4-->
+<!--page 181 -->
<pre>
extern int atoi(const char *);
const char *str;
</small>
<a name="7.2" href="#7.2"><h3>7.2 Diagnostics <assert.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.2"><assert.h></a> defines the assert macro and refers to another macro,
<pre>
NDEBUG</pre>
#define assert(ignore) ((void)0)</pre>
The assert macro is redefined according to the current state of NDEBUG each time that
<a href="#7.2"><assert.h></a> is included.
-<p><!--para 2-->
+<p><!--para 2 -->
The assert macro shall be implemented as a macro, not as an actual function. If the
macro definition is suppressed in order to access an actual function, the behavior is
undefined.
<a name="7.2.1.1" href="#7.2.1.1"><h5>7.2.1.1 The assert macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.2"><assert.h></a>
void assert(scalar expression);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The assert macro puts diagnostic tests into programs; it expands to a void expression.
When it is executed, if expression (which shall have a scalar type) is false (that is,
compares equal to 0), the assert macro writes information about the particular call that
__func__) on the standard error stream in an implementation-defined format.<sup><a href="#note165"><b>165)</b></a></sup> It
then calls the abort function.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The assert macro returns no value.
<p><b> Forward references</b>: the abort function (<a href="#7.20.4.1">7.20.4.1</a>).
-<!--page 182 indent 4-->
+<!--page 182 -->
<h6>footnotes</h6>
<p><small><a name="note165" href="#note165">165)</a> The message written might be of the form:
<a name="7.3" href="#7.3"><h3>7.3 Complex arithmetic <complex.h></h3></a>
<a name="7.3.1" href="#7.3.1"><h4>7.3.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.3"><complex.h></a> defines macros and declares functions that support complex
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
return values.
-<p><!--para 2-->
+<p><!--para 2 -->
The macro
<pre>
complex</pre>
_Complex_I</pre>
expands to a constant expression of type const float _Complex, with the value of
the imaginary unit.<sup><a href="#note167"><b>167)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The macros
<pre>
imaginary</pre>
are defined if and only if the implementation supports imaginary types;<sup><a href="#note168"><b>168)</b></a></sup> if defined,
they expand to _Imaginary and a constant expression of type const float
_Imaginary with the value of the imaginary unit.
-<p><!--para 4-->
+<p><!--para 4 -->
The macro
<pre>
I</pre>
expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is not
defined, I shall expand to _Complex_I.
-<p><!--para 5-->
+<p><!--para 5 -->
Notwithstanding the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and perhaps then
redefine the macros complex, imaginary, and I.
<p><b> Forward references</b>: IEC 60559-compatible complex arithmetic (<a href="#G">annex G</a>).
-<!--page 183 indent 4-->
+<!--page 183 -->
<h6>footnotes</h6>
<p><small><a name="note166" href="#note166">166)</a> See ''future library directions'' (<a href="#7.26.1">7.26.1</a>).
</small>
<a name="7.3.2" href="#7.3.2"><h4>7.3.2 Conventions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Values are interpreted as radians, not degrees. An implementation may set errno but is
not required to.
<a name="7.3.3" href="#7.3.3"><h4>7.3.3 Branch cuts</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Some of the functions below have branch cuts, across which the function is
discontinuous. For implementations with a signed zero (including all IEC 60559
implementations) that follow the specifications of <a href="#G">annex G</a>, the sign of zero distinguishes
function, which has a branch cut along the negative real axis, the top of the cut, with
imaginary part +0, maps to the positive imaginary axis, and the bottom of the cut, with
imaginary part -0, maps to the negative imaginary axis.
-<p><!--para 2-->
+<p><!--para 2 -->
Implementations that do not support a signed zero (see <a href="#F">annex F</a>) cannot distinguish the
sides of branch cuts. These implementations shall map a cut so the function is continuous
as the cut is approached coming around the finite endpoint of the cut in a counter
<a name="7.3.4" href="#7.3.4"><h4>7.3.4 The CX_LIMITED_RANGE pragma</h4></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
#pragma STDC CX_LIMITED_RANGE on-off-switch</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The usual mathematical formulas for complex multiply, divide, and absolute value are
problematic because of their treatment of infinities and because of undue overflow and
underflow. The CX_LIMITED_RANGE pragma can be used to inform the
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
-<!--page 184 indent 4-->
+<!--page 184 -->
declarations, the pragma takes effect from its occurrence until another
CX_LIMITED_RANGE pragma is encountered, or until the end of the translation unit.
When inside a compound statement, the pragma takes effect from its occurrence until
<a name="7.3.5.1" href="#7.3.5.1"><h5>7.3.5.1 The cacos functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacos(double complex z);
float complex cacosf(float complex z);
long double complex cacosl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cacos functions compute the complex arc cosine of z, with branch cuts outside the
interval [-1, +1] along the real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cacos functions return the complex arc cosine value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [0, pi ] along the
real axis.
<a name="7.3.5.2" href="#7.3.5.2"><h5>7.3.5.2 The casin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casin(double complex z);
float complex casinf(float complex z);
long double complex casinl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The casin functions compute the complex arc sine of z, with branch cuts outside the
interval [-1, +1] along the real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The casin functions return the complex arc sine value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
along the real axis.
-<!--page 185 indent 4-->
+<!--page 185 -->
<a name="7.3.5.3" href="#7.3.5.3"><h5>7.3.5.3 The catan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catan(double complex z);
float complex catanf(float complex z);
long double complex catanl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The catan functions compute the complex arc tangent of z, with branch cuts outside the
interval [-i, +i] along the imaginary axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The catan functions return the complex arc tangent value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
along the real axis.
<a name="7.3.5.4" href="#7.3.5.4"><h5>7.3.5.4 The ccos functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccos(double complex z);
float complex ccosf(float complex z);
long double complex ccosl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ccos functions compute the complex cosine of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ccos functions return the complex cosine value.
<a name="7.3.5.5" href="#7.3.5.5"><h5>7.3.5.5 The csin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csin(double complex z);
float complex csinf(float complex z);
long double complex csinl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The csin functions compute the complex sine of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The csin functions return the complex sine value.
-<!--page 186 indent 4-->
+<!--page 186 -->
<a name="7.3.5.6" href="#7.3.5.6"><h5>7.3.5.6 The ctan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctan(double complex z);
float complex ctanf(float complex z);
long double complex ctanl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ctan functions compute the complex tangent of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ctan functions return the complex tangent value.
<a name="7.3.6" href="#7.3.6"><h4>7.3.6 Hyperbolic functions</h4></a>
<a name="7.3.6.1" href="#7.3.6.1"><h5>7.3.6.1 The cacosh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacosh(double complex z);
float complex cacoshf(float complex z);
long double complex cacoshl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cacosh functions compute the complex arc hyperbolic cosine of z, with a branch
cut at values less than 1 along the real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cacosh functions return the complex arc hyperbolic cosine value, in the range of a
half-strip of non-negative values along the real axis and in the interval [-ipi , +ipi ] along
the imaginary axis.
<a name="7.3.6.2" href="#7.3.6.2"><h5>7.3.6.2 The casinh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casinh(double complex z);
float complex casinhf(float complex z);
long double complex casinhl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The casinh functions compute the complex arc hyperbolic sine of z, with branch cuts
outside the interval [-i, +i] along the imaginary axis.
-<!--page 187 indent 4-->
+<!--page 187 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The casinh functions return the complex arc hyperbolic sine value, in the range of a
strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
along the imaginary axis.
<a name="7.3.6.3" href="#7.3.6.3"><h5>7.3.6.3 The catanh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catanh(double complex z);
float complex catanhf(float complex z);
long double complex catanhl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The catanh functions compute the complex arc hyperbolic tangent of z, with branch
cuts outside the interval [-1, +1] along the real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The catanh functions return the complex arc hyperbolic tangent value, in the range of a
strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
along the imaginary axis.
<a name="7.3.6.4" href="#7.3.6.4"><h5>7.3.6.4 The ccosh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccosh(double complex z);
float complex ccoshf(float complex z);
long double complex ccoshl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ccosh functions compute the complex hyperbolic cosine of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ccosh functions return the complex hyperbolic cosine value.
<a name="7.3.6.5" href="#7.3.6.5"><h5>7.3.6.5 The csinh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 188 indent 4-->
+<p><!--para 1 -->
+<!--page 188 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csinh(double complex z);
float complex csinhf(float complex z);
long double complex csinhl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The csinh functions compute the complex hyperbolic sine of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The csinh functions return the complex hyperbolic sine value.
<a name="7.3.6.6" href="#7.3.6.6"><h5>7.3.6.6 The ctanh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctanh(double complex z);
float complex ctanhf(float complex z);
long double complex ctanhl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ctanh functions compute the complex hyperbolic tangent of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ctanh functions return the complex hyperbolic tangent value.
<a name="7.3.7" href="#7.3.7"><h4>7.3.7 Exponential and logarithmic functions</h4></a>
<a name="7.3.7.1" href="#7.3.7.1"><h5>7.3.7.1 The cexp functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cexp(double complex z);
float complex cexpf(float complex z);
long double complex cexpl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cexp functions compute the complex base-e exponential of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cexp functions return the complex base-e exponential value.
<a name="7.3.7.2" href="#7.3.7.2"><h5>7.3.7.2 The clog functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 189 indent 4-->
+<p><!--para 1 -->
+<!--page 189 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex clog(double complex z);
float complex clogf(float complex z);
long double complex clogl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The clog functions compute the complex natural (base-e) logarithm of z, with a branch
cut along the negative real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The clog functions return the complex natural logarithm value, in the range of a strip
mathematically unbounded along the real axis and in the interval [-ipi , +ipi ] along the
imaginary axis.
<a name="7.3.8.1" href="#7.3.8.1"><h5>7.3.8.1 The cabs functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cabs(double complex z);
float cabsf(float complex z);
long double cabsl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cabs functions compute the complex absolute value (also called norm, modulus, or
magnitude) of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cabs functions return the complex absolute value.
<a name="7.3.8.2" href="#7.3.8.2"><h5>7.3.8.2 The cpow functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cpow(double complex x, double complex y);
long double complex cpowl(long double complex x,
long double complex y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cpow functions compute the complex power function xy , with a branch cut for the
first parameter along the negative real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cpow functions return the complex power function value.
-<!--page 190 indent 4-->
+<!--page 190 -->
<a name="7.3.8.3" href="#7.3.8.3"><h5>7.3.8.3 The csqrt functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csqrt(double complex z);
float complex csqrtf(float complex z);
long double complex csqrtl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The csqrt functions compute the complex square root of z, with a branch cut along the
negative real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The csqrt functions return the complex square root value, in the range of the right half-
plane (including the imaginary axis).
<a name="7.3.9.1" href="#7.3.9.1"><h5>7.3.9.1 The carg functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double carg(double complex z);
float cargf(float complex z);
long double cargl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The carg functions compute the argument (also called phase angle) of z, with a branch
cut along the negative real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The carg functions return the value of the argument in the interval [-pi , +pi ].
<a name="7.3.9.2" href="#7.3.9.2"><h5>7.3.9.2 The cimag functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 191 indent 4-->
+<p><!--para 1 -->
+<!--page 191 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cimag(double complex z);
float cimagf(float complex z);
long double cimagl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cimag functions compute the imaginary part of z.<sup><a href="#note170"><b>170)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cimag functions return the imaginary part value (as a real).
<h6>footnotes</h6>
<a name="7.3.9.3" href="#7.3.9.3"><h5>7.3.9.3 The conj functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex conj(double complex z);
float complex conjf(float complex z);
long double complex conjl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The conj functions compute the complex conjugate of z, by reversing the sign of its
imaginary part.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The conj functions return the complex conjugate value.
<a name="7.3.9.4" href="#7.3.9.4"><h5>7.3.9.4 The cproj functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cproj(double complex z);
float complex cprojf(float complex z);
long double complex cprojl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cproj functions compute a projection of z onto the Riemann sphere: z projects to
z except that all complex infinities (even those with one infinite part and one NaN part)
project to positive infinity on the real axis. If z has an infinite part, then cproj(z) is
<pre>
INFINITY + I * copysign(0.0, cimag(z))</pre>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cproj functions return the value of the projection onto the Riemann sphere.
-<!--page 192 indent 4-->
+<!--page 192 -->
<a name="7.3.9.5" href="#7.3.9.5"><h5>7.3.9.5 The creal functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double creal(double complex z);
float crealf(float complex z);
long double creall(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The creal functions compute the real part of z.<sup><a href="#note171"><b>171)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The creal functions return the real part value.
-<!--page 193 indent 4-->
+<!--page 193 -->
<h6>footnotes</h6>
<p><small><a name="note171" href="#note171">171)</a> For a variable z of complex type, z == creal(z) + cimag(z)*I.
</small>
<a name="7.4" href="#7.4"><h3>7.4 Character handling <ctype.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.4"><ctype.h></a> declares several functions useful for classifying and mapping
characters.<sup><a href="#note172"><b>172)</b></a></sup> In all cases the argument is an int, the value of which shall be
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.
-<p><!--para 2-->
+<p><!--para 2 -->
The behavior of these functions is affected by the current locale. Those functions that
have locale-specific aspects only when not in the "C" locale are noted below.
-<p><!--para 3-->
+<p><!--para 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
</small>
<a name="7.4.1" href="#7.4.1"><h4>7.4.1 Character classification functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions in this subclause return nonzero (true) if and only if the value of the
argument c conforms to that in the description of the function.
<a name="7.4.1.1" href="#7.4.1.1"><h5>7.4.1.1 The isalnum function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isalnum(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isalnum function tests for any character for which isalpha or isdigit is true.
<a name="7.4.1.2" href="#7.4.1.2"><h5>7.4.1.2 The isalpha function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isalpha(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isalpha function tests for any character for which isupper or islower is true,
or any character that is one of a locale-specific set of alphabetic characters for which
-<!--page 194 indent 4-->
+<!--page 194 -->
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"><h5>7.4.1.3 The isblank function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isblank(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isblank function tests for any character that is a standard blank character or is one
of a locale-specific set of characters for which isspace is true and that is used to
separate words within a line of text. The standard blank characters are the following:
<a name="7.4.1.4" href="#7.4.1.4"><h5>7.4.1.4 The iscntrl function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int iscntrl(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iscntrl function tests for any control character.
<a name="7.4.1.5" href="#7.4.1.5"><h5>7.4.1.5 The isdigit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isdigit(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isdigit function tests for any decimal-digit character (as defined in <a href="#5.2.1">5.2.1</a>).
<a name="7.4.1.6" href="#7.4.1.6"><h5>7.4.1.6 The isgraph function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isgraph(int c);</pre>
-<!--page 195 indent 4-->
+<!--page 195 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isgraph function tests for any printing character except space (' ').
<a name="7.4.1.7" href="#7.4.1.7"><h5>7.4.1.7 The islower function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int islower(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The islower function tests for any character that is a lowercase letter or is one of a
locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
isspace is true. In the "C" locale, islower returns true only for the lowercase
<a name="7.4.1.8" href="#7.4.1.8"><h5>7.4.1.8 The isprint function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isprint(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isprint function tests for any printing character including space (' ').
<a name="7.4.1.9" href="#7.4.1.9"><h5>7.4.1.9 The ispunct function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int ispunct(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ispunct function tests for any printing character that is one of a locale-specific set
of punctuation characters for which neither isspace nor isalnum is true. In the "C"
locale, ispunct returns true for every printing character for which neither isspace
<a name="7.4.1.10" href="#7.4.1.10"><h5>7.4.1.10 The isspace function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isspace(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isspace function tests for any character that is a standard white-space character or
is one of a locale-specific set of characters for which isalnum is false. The standard
-<!--page 196 indent 4-->
+<!--page 196 -->
white-space characters are the following: space (' '), form feed ('\f'), new-line
('\n'), carriage return ('\r'), horizontal tab ('\t'), and vertical tab ('\v'). In the
"C" locale, isspace returns true only for the standard white-space characters.
<a name="7.4.1.11" href="#7.4.1.11"><h5>7.4.1.11 The isupper function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isupper(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isupper function tests for any character that is an uppercase letter or is one of a
locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
isspace is true. In the "C" locale, isupper returns true only for the uppercase
<a name="7.4.1.12" href="#7.4.1.12"><h5>7.4.1.12 The isxdigit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isxdigit(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isxdigit function tests for any hexadecimal-digit character (as defined in <a href="#6.4.4.1">6.4.4.1</a>).
<a name="7.4.2" href="#7.4.2"><h4>7.4.2 Character case mapping functions</h4></a>
<a name="7.4.2.1" href="#7.4.2.1"><h5>7.4.2.1 The tolower function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int tolower(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tolower function converts an uppercase letter to a corresponding lowercase letter.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a character for which isupper is true and there are one or more
corresponding characters, as specified by the current locale, for which islower is true,
the tolower function returns one of the corresponding characters (always the same one
for any given locale); otherwise, the argument is returned unchanged.
-<!--page 197 indent 4-->
+<!--page 197 -->
<a name="7.4.2.2" href="#7.4.2.2"><h5>7.4.2.2 The toupper function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int toupper(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The toupper function converts a lowercase letter to a corresponding uppercase letter.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a character for which islower is true and there are one or more
corresponding characters, as specified by the current locale, for which isupper is true,
the toupper function returns one of the corresponding characters (always the same one
for any given locale); otherwise, the argument is returned unchanged.
-<!--page 198 indent 4-->
+<!--page 198 -->
<a name="7.5" href="#7.5"><h3>7.5 Errors <errno.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.5"><errno.h></a> defines several macros, all relating to the reporting of error
conditions.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros are
<pre>
EDOM
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.
-<p><!--para 3-->
+<p><!--para 3 -->
The value of errno is zero at program startup, but is never set to zero by any library
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.
-<p><!--para 4-->
+<p><!--para 4 -->
Additional macro definitions, beginning with E and a digit or E and an uppercase
letter,<sup><a href="#note177"><b>177)</b></a></sup> may also be specified by the implementation.
-<!--page 199 indent 4-->
+<!--page 199 -->
<h6>footnotes</h6>
<p><small><a name="note175" href="#note175">175)</a> The macro errno need not be the identifier of an object. It might expand to a modifiable lvalue
</small>
<a name="7.6" href="#7.6"><h3>7.6 Floating-point environment <fenv.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.6"><fenv.h></a> declares two types and several macros and functions to provide
access to the floating-point environment. The floating-point environment refers
collectively to any floating-point status flags and control modes supported by the
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.
-<p><!--para 2-->
+<p><!--para 2 -->
Certain programming conventions support the intended model of use for the floating-
point environment:<sup><a href="#note180"><b>180)</b></a></sup>
<ul>
<li> a function call is assumed to have the potential for raising floating-point exceptions,
unless its documentation promises otherwise.
</ul>
-<p><!--para 3-->
+<p><!--para 3 -->
The type
<pre>
fenv_t</pre>
represents the entire floating-point environment.
-<p><!--para 4-->
+<p><!--para 4 -->
The type
<pre>
fexcept_t</pre>
-<!--page 200 indent 4-->
-<p><!--para 5-->
+<!--page 200 -->
+<p><!--para 5 -->
Each of the macros
<pre>
FE_DIVBYZERO
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.<sup><a href="#note182"><b>182)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 6 -->
The macro
<pre>
FE_ALL_EXCEPT</pre>
is simply the bitwise OR of all floating-point exception macros defined by the
implementation. If no such macros are defined, FE_ALL_EXCEPT shall be defined as 0.
-<p><!--para 7-->
+<p><!--para 7 -->
Each of the macros
<pre>
FE_DOWNWARD
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.<sup><a href="#note183"><b>183)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
The macro
-<!--page 201 indent 4-->
+<!--page 201 -->
<pre>
FE_DFL_ENV</pre>
represents the default floating-point environment -- the one installed at program startup
<li> and has type ''pointer to const-qualified fenv_t''. It can be used as an argument to
</ul>
<a href="#7.6"><fenv.h></a> functions that manage the floating-point environment.
-<p><!--para 9-->
+<p><!--para 9 -->
Additional implementation-defined environments, with macro definitions beginning with
FE_ and an uppercase letter, and having type ''pointer to const-qualified fenv_t'', may
also be specified by the implementation.
<a name="7.6.1" href="#7.6.1"><h4>7.6.1 The FENV_ACCESS pragma</h4></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS on-off-switch</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The FENV_ACCESS pragma provides a means to inform the implementation when a
program might access the floating-point environment to test floating-point status flags or
run under non-default floating-point control modes.<sup><a href="#note184"><b>184)</b></a></sup> The pragma shall occur either
-<!--page 202 indent 4-->
-<p><!--para 3-->
+<!--page 202 -->
+<p><!--para 3 -->
EXAMPLE
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
void f(double x)
</small>
<a name="7.6.2" href="#7.6.2"><h4>7.6.2 Floating-point exceptions</h4></a>
-<p><!--para 1-->
+<p><!--para 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
<a name="7.6.2.1" href="#7.6.2.1"><h5>7.6.2.1 The feclearexcept function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int feclearexcept(int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feclearexcept function attempts to clear the supported floating-point exceptions
represented by its argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feclearexcept function returns zero if the excepts argument is zero or if all
the specified exceptions were successfully cleared. Otherwise, it returns a nonzero value.
-<!--page 203 indent 4-->
+<!--page 203 -->
<a name="7.6.2.2" href="#7.6.2.2"><h5>7.6.2.2 The fegetexceptflag function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetexceptflag(fexcept_t *flagp,
int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fegetexceptflag function attempts to store an implementation-defined
representation of the states of the floating-point status flags indicated by the argument
excepts in the object pointed to by the argument flagp.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fegetexceptflag function returns zero if the representation was successfully
stored. Otherwise, it returns a nonzero value.
<a name="7.6.2.3" href="#7.6.2.3"><h5>7.6.2.3 The feraiseexcept function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int feraiseexcept(int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feraiseexcept function attempts to raise the supported floating-point exceptions
represented by its argument.<sup><a href="#note187"><b>187)</b></a></sup> The order in which these floating-point exceptions are
raised is unspecified, except as stated in <a href="#F.7.6">F.7.6</a>. Whether the feraiseexcept function
additionally raises the ''inexact'' floating-point exception whenever it raises the
''overflow'' or ''underflow'' floating-point exception is implementation-defined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feraiseexcept function returns zero if the excepts argument is zero or if all
the specified exceptions were successfully raised. Otherwise, it returns a nonzero value.
-<!--page 204 indent 4-->
+<!--page 204 -->
<h6>footnotes</h6>
<p><small><a name="note187" href="#note187">187)</a> The effect is intended to be similar to that of floating-point exceptions raised by arithmetic operations.
<a name="7.6.2.4" href="#7.6.2.4"><h5>7.6.2.4 The fesetexceptflag function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetexceptflag(const fexcept_t *flagp,
int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fesetexceptflag function attempts to set the floating-point status flags
indicated by the argument excepts to the states stored in the object pointed to by
flagp. The value of *flagp shall have been set by a previous call to
exceptions represented by the argument excepts. This function does not raise floating-
point exceptions, but only sets the state of the flags.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fesetexceptflag function returns zero if the excepts argument is zero or if
all the specified flags were successfully set to the appropriate state. Otherwise, it returns
a nonzero value.
<a name="7.6.2.5" href="#7.6.2.5"><h5>7.6.2.5 The fetestexcept function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fetestexcept(int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fetestexcept function determines which of a specified subset of the floating-
point exception flags are currently set. The excepts argument specifies the floating-
point status flags to be queried.<sup><a href="#note188"><b>188)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fetestexcept function returns the value of the bitwise OR of the floating-point
exception macros corresponding to the currently set floating-point exceptions included in
excepts.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE Call f if ''invalid'' is set, then g if ''overflow'' is set:
-<!--page 205 indent 4-->
+<!--page 205 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
/* ... */
</small>
<a name="7.6.3" href="#7.6.3"><h4>7.6.3 Rounding</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The fegetround and fesetround functions provide control of rounding direction
modes.
<a name="7.6.3.1" href="#7.6.3.1"><h5>7.6.3.1 The fegetround function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetround(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fegetround function gets the current rounding direction.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fegetround function returns the value of the rounding direction macro
representing the current rounding direction or a negative value if there is no such
rounding direction macro or the current rounding direction is not determinable.
<a name="7.6.3.2" href="#7.6.3.2"><h5>7.6.3.2 The fesetround function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetround(int round);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fesetround function establishes the rounding direction represented by its
argument round. If the argument is not equal to the value of a rounding direction macro,
the rounding direction is not changed.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fesetround function returns zero if and only if the requested rounding direction
was established.
-<!--page 206 indent 4-->
-<p><!--para 4-->
+<!--page 206 -->
+<p><!--para 4 -->
EXAMPLE Save, set, and restore the rounding direction. Report an error and abort if setting the
rounding direction fails.
<pre>
<a name="7.6.4" href="#7.6.4"><h4>7.6.4 Environment</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions in this section manage the floating-point environment -- status flags and
control modes -- as one entity.
<a name="7.6.4.1" href="#7.6.4.1"><h5>7.6.4.1 The fegetenv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetenv(fenv_t *envp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fegetenv function attempts to store the current floating-point environment in the
object pointed to by envp.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fegetenv function returns zero if the environment was successfully stored.
Otherwise, it returns a nonzero value.
<a name="7.6.4.2" href="#7.6.4.2"><h5>7.6.4.2 The feholdexcept function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int feholdexcept(fenv_t *envp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feholdexcept function saves the current floating-point environment in the object
pointed to by envp, clears the floating-point status flags, and then installs a non-stop
(continue on floating-point exceptions) mode, if available, for all floating-point
exceptions.<sup><a href="#note189"><b>189)</b></a></sup>
-<!--page 207 indent 4-->
+<!--page 207 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feholdexcept function returns zero if and only if non-stop floating-point
exception handling was successfully installed.
<a name="7.6.4.3" href="#7.6.4.3"><h5>7.6.4.3 The fesetenv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetenv(const fenv_t *envp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fesetenv function attempts to establish the floating-point environment represented
by the object pointed to by envp. The argument envp shall point to an object set by a
call to fegetenv or feholdexcept, or equal a floating-point environment macro.
Note that fesetenv merely installs the state of the floating-point status flags
represented through its argument, and does not raise these floating-point exceptions.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fesetenv function returns zero if the environment was successfully established.
Otherwise, it returns a nonzero value.
<a name="7.6.4.4" href="#7.6.4.4"><h5>7.6.4.4 The feupdateenv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int feupdateenv(const fenv_t *envp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feupdateenv function attempts to save the currently raised floating-point
exceptions in its automatic storage, install the floating-point environment represented by
the object pointed to by envp, and then raise the saved floating-point exceptions. The
argument envp shall point to an object set by a call to feholdexcept or fegetenv,
or equal a floating-point environment macro.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feupdateenv function returns zero if all the actions were successfully carried out.
Otherwise, it returns a nonzero value.
-<!--page 208 indent 4-->
-<p><!--para 4-->
+<!--page 208 -->
+<p><!--para 4 -->
EXAMPLE Hide spurious underflow floating-point exceptions:
-<!--page 209 indent 4-->
+<!--page 209 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
double f(double x)
}</pre>
<a name="7.7" href="#7.7"><h3>7.7 Characteristics of floating types <float.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.7"><float.h></a> defines several macros that expand to various limits and
parameters of the standard floating-point types.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros, their meanings, and the constraints (or restrictions) on their values are listed
in <a href="#5.2.4.2.2">5.2.4.2.2</a>.
-<!--page 210 indent 4-->
+<!--page 210 -->
<a name="7.8" href="#7.8"><h3>7.8 Format conversion of integer types <inttypes.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.8"><inttypes.h></a> includes the header <a href="#7.18"><stdint.h></a> and extends it with
additional facilities provided by hosted implementations.
-<p><!--para 2-->
+<p><!--para 2 -->
It declares functions for manipulating greatest-width integers and converting numeric
character strings to greatest-width integers, and it declares the type
<pre>
</small>
<a name="7.8.1" href="#7.8.1"><h4>7.8.1 Macros for format specifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 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
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.
-<p><!--para 2-->
+<p><!--para 2 -->
The fprintf macros for signed integers are:
<pre>
PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR
-<!--page 211 indent 4-->
-<p><!--para 3-->
+<!--page 211 -->
+<p><!--para 3 -->
The fprintf macros for unsigned integers are:
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR
PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR
PRIxN PRIxLEASTN PRIxFASTN PRIxMAX PRIxPTR
PRIXN PRIXLEASTN PRIXFASTN PRIXMAX PRIXPTR</pre>
The fscanf macros for signed integers are:
-<p><!--para 5-->
+<p><!--para 5 -->
<pre>
SCNdN SCNdLEASTN SCNdFASTN SCNdMAX SCNdPTR
SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR</pre>
The fscanf macros for unsigned integers are:
-<p><!--para 6-->
+<p><!--para 6 -->
<pre>
SCNoN SCNoLEASTN SCNoFASTN SCNoMAX SCNoPTR
SCNuN SCNuLEASTN SCNuFASTN SCNuMAX SCNuPTR
fprintf macros shall be defined and the corresponding fscanf macros shall be
defined unless the implementation does not have a suitable fscanf length modifier for
the type.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE
<pre>
#include <a href="#7.8"><inttypes.h></a>
<a name="7.8.2.1" href="#7.8.2.1"><h5>7.8.2.1 The imaxabs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
intmax_t imaxabs(intmax_t j);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The imaxabs function computes the absolute value of an integer j. If the result cannot
be represented, the behavior is undefined.<sup><a href="#note193"><b>193)</b></a></sup>
-<!--page 212 indent 4-->
+<!--page 212 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The imaxabs function returns the absolute value.
<h6>footnotes</h6>
<a name="7.8.2.2" href="#7.8.2.2"><h5>7.8.2.2 The imaxdiv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The imaxdiv function computes numer / denom and numer % denom in a single
operation.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The imaxdiv function returns a structure of type imaxdiv_t comprising both the
quotient and the remainder. The structure shall contain (in either order) the members
quot (the quotient) and rem (the remainder), each of which has type intmax_t. If
<a name="7.8.2.3" href="#7.8.2.3"><h5>7.8.2.3 The strtoimax and strtoumax functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
intmax_t strtoimax(const char * restrict nptr,
uintmax_t strtoumax(const char * restrict nptr,
char ** restrict endptr, int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strtoimax and strtoumax functions are equivalent to the strtol, strtoll,
strtoul, and strtoull functions, except that the initial portion of the string is
converted to intmax_t and uintmax_t representation, respectively.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strtoimax and strtoumax functions return the converted value, if any. If no
conversion could be performed, zero is returned. If the correct value is outside the range
of representable values, INTMAX_MAX, INTMAX_MIN, or UINTMAX_MAX is returned
ERANGE is stored in errno.
<p><b> Forward references</b>: the strtol, strtoll, strtoul, and strtoull functions
(<a href="#7.20.1.4">7.20.1.4</a>).
-<!--page 213 indent 4-->
+<!--page 213 -->
<a name="7.8.2.4" href="#7.8.2.4"><h5>7.8.2.4 The wcstoimax and wcstoumax functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stddef.h></a> // for wchar_t
#include <a href="#7.8"><inttypes.h></a>
uintmax_t wcstoumax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcstoimax and wcstoumax functions are equivalent to the wcstol, wcstoll,
wcstoul, and wcstoull functions except that the initial portion of the wide string is
converted to intmax_t and uintmax_t representation, respectively.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcstoimax function returns the converted value, if any. If no conversion could be
performed, zero is returned. If the correct value is outside the range of representable
values, INTMAX_MAX, INTMAX_MIN, or UINTMAX_MAX is returned (according to the
errno.
<p><b> Forward references</b>: the wcstol, wcstoll, wcstoul, and wcstoull functions
(<a href="#7.24.4.1.2">7.24.4.1.2</a>).
-<!--page 214 indent 4-->
+<!--page 214 -->
<a name="7.9" href="#7.9"><h3>7.9 Alternative spellings <iso646.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.9"><iso646.h></a> defines the following eleven macros (on the left) that expand
to the corresponding tokens (on the right):
-<!--page 215 indent 4-->
+<!--page 215 -->
<pre>
and &&
and_eq &=
xor_eq ^=</pre>
<a name="7.10" href="#7.10"><h3>7.10 Sizes of integer types <limits.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.10"><limits.h></a> defines several macros that expand to various limits and
parameters of the standard integer types.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros, their meanings, and the constraints (or restrictions) on their values are listed
in <a href="#5.2.4.2.1">5.2.4.2.1</a>.
-<!--page 216 indent 4-->
+<!--page 216 -->
<a name="7.11" href="#7.11"><h3>7.11 Localization <locale.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.11"><locale.h></a> declares two functions, one type, and defines several macros.
-<p><!--para 2-->
+<p><!--para 2 -->
The type is
<pre>
struct lconv</pre>
contain at least the following members, in any order. The semantics of the members and
their normal ranges are explained in <a href="#7.11.2.1">7.11.2.1</a>. In the "C" locale, the members shall have
the values specified in the comments.
-<!--page 217 indent 4-->
-<p><!--para 3-->
+<!--page 217 -->
+<p><!--para 3 -->
<pre>
char *decimal_point; // "."
char *thousands_sep; // ""
<a name="7.11.1.1" href="#7.11.1.1"><h5>7.11.1.1 The setlocale function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.11"><locale.h></a>
char *setlocale(int category, const char *locale);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The setlocale function selects the appropriate portion of the program's locale as
specified by the category and locale arguments. The setlocale function may be
used to change or query the program's entire current locale or portions thereof. The value
formatted input/output functions and the string conversion functions, as well as the
nonmonetary formatting information returned by the localeconv function. LC_TIME
affects the behavior of the strftime and wcsftime functions.
-<p><!--para 3-->
+<p><!--para 3 -->
A value of "C" for locale specifies the minimal environment for C translation; a value
of "" for locale specifies the locale-specific native environment. Other
implementation-defined strings may be passed as the second argument to setlocale.
-<!--page 218 indent 4-->
-<p><!--para 4-->
+<!--page 218 -->
+<p><!--para 4 -->
At program startup, the equivalent of
<pre>
setlocale(LC_ALL, "C");</pre>
is executed.
-<p><!--para 5-->
+<p><!--para 5 -->
The implementation shall behave as if no library function calls the setlocale function.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
If a pointer to a string is given for locale and the selection can be honored, the
setlocale function returns a pointer to the string associated with the specified
category for the new locale. If the selection cannot be honored, the setlocale
function returns a null pointer and the program's locale is not changed.
-<p><!--para 7-->
+<p><!--para 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.<sup><a href="#note197"><b>197)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 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
<a name="7.11.2.1" href="#7.11.2.1"><h5>7.11.2.1 The localeconv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.11"><locale.h></a>
struct lconv *localeconv(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The localeconv function sets the components of an object with type struct lconv
with values appropriate for the formatting of numeric quantities (monetary and otherwise)
according to the rules of the current locale.
-<p><!--para 3-->
+<p><!--para 3 -->
The members of the structure with type char * are pointers to strings, any of which
(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
-<!--page 219 indent 0-->
+<!--page 219 -->
strings shall start and end in the initial shift state. The members with type char are
nonnegative numbers, any of which can be CHAR_MAX to indicate that the value is not
available in the current locale. The members include the following:
Set to 1 or 0 if the currency_symbol respectively precedes or
succeeds the value for a nonnegative locally formatted monetary quantity.</pre>
char n_cs_precedes
-<!--page 220 indent 0-->
+<!--page 220 -->
<pre>
Set to 1 or 0 if the currency_symbol respectively precedes or
succeeds the value for a negative locally formatted monetary quantity.</pre>
succeeds the value for a negative internationally formatted monetary
quantity.</pre>
char int_p_sep_by_space
-<!--page 221 indent 4-->
+<!--page 221 -->
<pre>
Set to a value indicating the separation of the int_curr_symbol, the
sign string, and the value for a nonnegative internationally formatted
Set to a value indicating the positioning of the positive_sign for a
nonnegative internationally formatted monetary quantity.</pre>
char int_n_sign_posn
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
Set to a value indicating the positioning of the negative_sign for a
negative internationally formatted monetary quantity.</pre>
<pre>
digits.</pre>
other The integer value is the number of digits that compose the current group.
-<p><!--para 5-->
+<p><!--para 5 -->
<pre>
The next element is examined to determine the size of the next group of
digits before the current group.</pre>
otherwise, a space separates the sign string from the value.</pre>
For int_p_sep_by_space and int_n_sep_by_space, the fourth character of
int_curr_symbol is used instead of a space.
-<p><!--para 6-->
+<p><!--para 6 -->
The values of p_sign_posn, n_sign_posn, int_p_sign_posn, and
int_n_sign_posn are interpreted according to the following:
0 Parentheses surround the quantity and currency symbol.
2 The sign string succeeds the quantity and currency symbol.
3 The sign string immediately precedes the currency symbol.
4 The sign string immediately succeeds the currency symbol.
-<!--page 222 indent 5-->
-<p><!--para 7-->
+<!--page 222 -->
+<p><!--para 7 -->
The implementation shall behave as if no library function calls the localeconv
function.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The localeconv function returns a pointer to the filled-in object. The structure
pointed to by the return value shall not be modified by the program, but may be
overwritten by a subsequent call to the localeconv function. In addition, calls to the
setlocale function with categories LC_ALL, LC_MONETARY, or LC_NUMERIC may
overwrite the contents of the structure.
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 1 The following table illustrates rules which may well be used by four countries to format
monetary quantities.
<pre>
Country2 L.1.234 -L.1.234 ITL 1.234 -ITL 1.234
Country3 fl. 1.234,56 fl. -1.234,56 NLG 1.234,56 NLG -1.234,56
Country4 SFrs.1,234.56 SFrs.1,234.56C CHF 1,234.56 CHF 1,234.56C
-<p><!--para 10-->
+<p><!--para 10 -->
For these four countries, the respective values for the monetary members of the structure returned by
localeconv could be:
<pre>
int_n_sep_by_space 2 1 2 1
int_p_sign_posn 1 1 1 1
int_n_sign_posn 4 1 4 2
-<!--page 223 indent 5-->
-<p><!--para 11-->
+<!--page 223 -->
+<p><!--para 11 -->
EXAMPLE 2 The following table illustrates how the cs_precedes, sep_by_space, and sign_posn members
affect the formatted value.
<pre>
3 <a href="#1.25">1.25</a>+$ <a href="#1.25">1.25</a> +$ <a href="#1.25">1.25</a>+ $
4 <a href="#1.25">1.25</a>$+ <a href="#1.25">1.25</a> $+ <a href="#1.25">1.25</a>$ +</pre>
-<!--page 224 indent 4-->
+<!--page 224 -->
<pre>
1 0 ($1.25) ($ <a href="#1.25">1.25</a>) ($1.25)
1 +$1.25 +$ <a href="#1.25">1.25</a> + $1.25
4 $+1.25 $+ <a href="#1.25">1.25</a> $ +1.25</pre>
<a name="7.12" href="#7.12"><h3>7.12 Mathematics <math.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.12"><math.h></a> declares two types and many mathematical functions and defines
several macros. Most synopses specify a family of functions consisting of a principal
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.<sup><a href="#note198"><b>198)</b></a></sup>
Integer arithmetic functions and conversion functions are discussed later.
-<p><!--para 2-->
+<p><!--para 2 -->
The types
<pre>
float_t
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.<sup><a href="#note199"><b>199)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The macro
<pre>
HUGE_VAL</pre>
HUGE_VALF
HUGE_VALL</pre>
are respectively float and long double analogs of HUGE_VAL.<sup><a href="#note200"><b>200)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
The macro
<pre>
INFINITY</pre>
-<!--page 225 indent 4-->
+<!--page 225 -->
translation time.<sup><a href="#note201"><b>201)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
The macro
<pre>
NAN</pre>
is defined if and only if the implementation supports quiet NaNs for the float type. It
expands to a constant expression of type float representing a quiet NaN.
-<p><!--para 6-->
+<p><!--para 6 -->
The number classification macros
<pre>
FP_INFINITE
constant expressions with distinct values. Additional implementation-defined floating-
point classifications, with macro definitions beginning with FP_ and an uppercase letter,
may also be specified by the implementation.
-<p><!--para 7-->
+<p><!--para 7 -->
The macro
<pre>
FP_FAST_FMA</pre>
FP_FAST_FMAL</pre>
are, respectively, float and long double analogs of FP_FAST_FMA. If defined,
these macros expand to the integer constant 1.
-<p><!--para 8-->
+<p><!--para 8 -->
The macros
<pre>
FP_ILOGB0
-INT_MAX. The value of FP_ILOGBNAN shall be either INT_MAX or INT_MIN.
-<!--page 226 indent 4-->
-<p><!--para 9-->
+<!--page 226 -->
+<p><!--para 9 -->
The macros
<pre>
MATH_ERRNO
</small>
<a name="7.12.1" href="#7.12.1"><h4>7.12.1 Treatment of error conditions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior of each of the functions in <a href="#7.12"><math.h></a> is specified for all representable
values of its input arguments, except where stated otherwise. Each function shall execute
as if it were a single operation without generating any externally visible exceptional
conditions.
-<p><!--para 2-->
+<p><!--para 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
expression math_errhandling & MATH_ERRNO is nonzero, the integer expression
errno acquires the value EDOM; if the integer expression math_errhandling &
MATH_ERREXCEPT is nonzero, the ''invalid'' floating-point exception is raised.
-<p><!--para 3-->
+<p><!--para 3 -->
Similarly, a range error occurs if the mathematical result of the function cannot be
represented in an object of the specified type, due to extreme magnitude.
-<p><!--para 4-->
+<p><!--para 4 -->
A floating result overflows if the magnitude of the mathematical result is finite but so
large that the mathematical result cannot be represented without extraordinary roundoff
error in an object of the specified type. If a floating result overflows and default rounding
example log(0.0)), then the function returns the value of the macro HUGE_VAL,
-<!--page 227 indent 4-->
+<!--page 227 -->
HUGE_VALF, or HUGE_VALL according to the return type, with the same sign as the
correct value of the function; if the integer expression math_errhandling &
MATH_ERRNO is nonzero, the integer expression errno acquires the value ERANGE; if
the integer expression math_errhandling & MATH_ERREXCEPT is nonzero, the
''divide-by-zero'' floating-point exception is raised if the mathematical result is an exact
infinity and the ''overflow'' floating-point exception is raised otherwise.
-<p><!--para 5-->
+<p><!--para 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.<sup><a href="#note204"><b>204)</b></a></sup> If the result underflows, the function returns an
<a name="7.12.2" href="#7.12.2"><h4>7.12.2 The FP_CONTRACT pragma</h4></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
#pragma STDC FP_CONTRACT on-off-switch</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The FP_CONTRACT pragma can be used to allow (if the state is ''on'') or disallow (if the
state is ''off'') the implementation to contract expressions (<a href="#6.5">6.5</a>). Each pragma can occur
either outside external declarations or preceding all explicit declarations and statements
-<!--page 228 indent 4-->
+<!--page 228 -->
<a name="7.12.3" href="#7.12.3"><h4>7.12.3 Classification macros</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In the synopses in this subclause, real-floating indicates that the argument shall be an
expression of real floating type.
<a name="7.12.3.1" href="#7.12.3.1"><h5>7.12.3.1 The fpclassify macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int fpclassify(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fpclassify macro classifies its argument value as NaN, infinite, normal,
subnormal, zero, or into another implementation-defined category. First, an argument
represented in a format wider than its semantic type is converted to its semantic type.
Then classification is based on the type of the argument.<sup><a href="#note205"><b>205)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fpclassify macro returns the value of the number classification macro
appropriate to the value of its argument.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The fpclassify macro might be implemented in terms of ordinary functions as
<pre>
#define fpclassify(x) \
<a name="7.12.3.2" href="#7.12.3.2"><h5>7.12.3.2 The isfinite macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isfinite(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isfinite macro determines whether its argument has a finite value (zero,
subnormal, or normal, and not infinite or NaN). First, an argument represented in a
format wider than its semantic type is converted to its semantic type. Then determination
-<!--page 229 indent 4-->
+<!--page 229 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isfinite macro returns a nonzero value if and only if its argument has a finite
value.
<a name="7.12.3.3" href="#7.12.3.3"><h5>7.12.3.3 The isinf macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isinf(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isinf macro determines whether its argument value is an infinity (positive or
negative). First, an argument represented in a format wider than its semantic type is
converted to its semantic type. Then determination is based on the type of the argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isinf macro returns a nonzero value if and only if its argument has an infinite
value.
<a name="7.12.3.4" href="#7.12.3.4"><h5>7.12.3.4 The isnan macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isnan(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isnan macro determines whether its argument value is a NaN. First, an argument
represented in a format wider than its semantic type is converted to its semantic type.
Then determination is based on the type of the argument.<sup><a href="#note206"><b>206)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isnan macro returns a nonzero value if and only if its argument has a NaN value.
<h6>footnotes</h6>
<a name="7.12.3.5" href="#7.12.3.5"><h5>7.12.3.5 The isnormal macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isnormal(real-floating x);</pre>
-<!--page 230 indent 4-->
+<!--page 230 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isnormal macro determines whether its argument value is normal (neither zero,
subnormal, infinite, nor NaN). First, an argument represented in a format wider than its
semantic type is converted to its semantic type. Then determination is based on the type
of the argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isnormal macro returns a nonzero value if and only if its argument has a normal
value.
<a name="7.12.3.6" href="#7.12.3.6"><h5>7.12.3.6 The signbit macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int signbit(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The signbit macro determines whether the sign of its argument value is negative.<sup><a href="#note207"><b>207)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The signbit macro returns a nonzero value if and only if the sign of its argument value
is negative.
<a name="7.12.4.1" href="#7.12.4.1"><h5>7.12.4.1 The acos functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double acos(double x);
float acosf(float x);
long double acosl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The acos functions compute the principal value of the arc cosine of x. A domain error
occurs for arguments not in the interval [-1, +1].
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The acos functions return arccos x in the interval [0, pi ] radians.
-<!--page 231 indent 4-->
+<!--page 231 -->
<a name="7.12.4.2" href="#7.12.4.2"><h5>7.12.4.2 The asin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double asin(double x);
float asinf(float x);
long double asinl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The asin functions compute the principal value of the arc sine of x. A domain error
occurs for arguments not in the interval [-1, +1].
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The asin functions return arcsin x in the interval [-pi /2, +pi /2] radians.
<a name="7.12.4.3" href="#7.12.4.3"><h5>7.12.4.3 The atan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atan(double x);
float atanf(float x);
long double atanl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atan functions compute the principal value of the arc tangent of x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atan functions return arctan x in the interval [-pi /2, +pi /2] radians.
<a name="7.12.4.4" href="#7.12.4.4"><h5>7.12.4.4 The atan2 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atan2(double y, double x);
float atan2f(float y, float x);
long double atan2l(long double y, long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atan2 functions compute the value of the arc tangent of y/x, using the signs of both
arguments to determine the quadrant of the return value. A domain error may occur if
both arguments are zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atan2 functions return arctan y/x in the interval [-pi , +pi ] radians.
-<!--page 232 indent 4-->
+<!--page 232 -->
<a name="7.12.4.5" href="#7.12.4.5"><h5>7.12.4.5 The cos functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cos(double x);
float cosf(float x);
long double cosl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cos functions compute the cosine of x (measured in radians).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cos functions return cos x.
<a name="7.12.4.6" href="#7.12.4.6"><h5>7.12.4.6 The sin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sin(double x);
float sinf(float x);
long double sinl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sin functions compute the sine of x (measured in radians).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sin functions return sin x.
<a name="7.12.4.7" href="#7.12.4.7"><h5>7.12.4.7 The tan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tan(double x);
float tanf(float x);
long double tanl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tan functions return the tangent of x (measured in radians).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tan functions return tan x.
-<!--page 233 indent 4-->
+<!--page 233 -->
<a name="7.12.5" href="#7.12.5"><h4>7.12.5 Hyperbolic functions</h4></a>
<a name="7.12.5.1" href="#7.12.5.1"><h5>7.12.5.1 The acosh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double acosh(double x);
float acoshf(float x);
long double acoshl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain
error occurs for arguments less than 1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The acosh functions return arcosh x in the interval [0, +(inf)].
<a name="7.12.5.2" href="#7.12.5.2"><h5>7.12.5.2 The asinh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double asinh(double x);
float asinhf(float x);
long double asinhl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The asinh functions compute the arc hyperbolic sine of x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The asinh functions return arsinh x.
<a name="7.12.5.3" href="#7.12.5.3"><h5>7.12.5.3 The atanh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atanh(double x);
float atanhf(float x);
long double atanhl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atanh functions compute the arc hyperbolic tangent of x. A domain error occurs
for arguments not in the interval [-1, +1]. A range error may occur if the argument
equals -1 or +1.
-<!--page 234 indent 4-->
+<!--page 234 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atanh functions return artanh x.
<a name="7.12.5.4" href="#7.12.5.4"><h5>7.12.5.4 The cosh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cosh(double x);
float coshf(float x);
long double coshl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cosh functions compute the hyperbolic cosine of x. A range error occurs if the
magnitude of x is too large.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cosh functions return cosh x.
<a name="7.12.5.5" href="#7.12.5.5"><h5>7.12.5.5 The sinh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sinh(double x);
float sinhf(float x);
long double sinhl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sinh functions compute the hyperbolic sine of x. A range error occurs if the
magnitude of x is too large.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sinh functions return sinh x.
<a name="7.12.5.6" href="#7.12.5.6"><h5>7.12.5.6 The tanh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tanh(double x);
float tanhf(float x);
long double tanhl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tanh functions compute the hyperbolic tangent of x.
-<!--page 235 indent 4-->
+<!--page 235 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tanh functions return tanh x.
<a name="7.12.6" href="#7.12.6"><h4>7.12.6 Exponential and logarithmic functions</h4></a>
<a name="7.12.6.1" href="#7.12.6.1"><h5>7.12.6.1 The exp functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double exp(double x);
float expf(float x);
long double expl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The exp functions compute the base-e exponential of x. A range error occurs if the
magnitude of x is too large.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The exp functions return ex .
<a name="7.12.6.2" href="#7.12.6.2"><h5>7.12.6.2 The exp2 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double exp2(double x);
float exp2f(float x);
long double exp2l(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The exp2 functions compute the base-2 exponential of x. A range error occurs if the
magnitude of x is too large.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The exp2 functions return 2x .
<a name="7.12.6.3" href="#7.12.6.3"><h5>7.12.6.3 The expm1 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 236 indent 4-->
+<p><!--para 1 -->
+<!--page 236 -->
<pre>
#include <a href="#7.12"><math.h></a>
double expm1(double x);
float expm1f(float x);
long double expm1l(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The expm1 functions compute the base-e exponential of the argument, minus 1. A range
error occurs if x is too large.<sup><a href="#note208"><b>208)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The expm1 functions return ex - 1.
<h6>footnotes</h6>
<a name="7.12.6.4" href="#7.12.6.4"><h5>7.12.6.4 The frexp functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double frexp(double value, int *exp);
float frexpf(float value, int *exp);
long double frexpl(long double value, int *exp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The frexp functions break a floating-point number into a normalized fraction and an
integral power of 2. They store the integer in the int object pointed to by exp.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If value is not a floating-point number, the results are unspecified. Otherwise, the
frexp functions return the value x, such that x has a magnitude in the interval [1/2, 1) or
zero, and value equals x x 2*exp . If value is zero, both parts of the result are zero.
<a name="7.12.6.5" href="#7.12.6.5"><h5>7.12.6.5 The ilogb functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int ilogb(double x);
int ilogbf(float x);
int ilogbl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ilogb functions extract the exponent of x as a signed int value. If x is zero they
compute the value FP_ILOGB0; if x is infinite they compute the value INT_MAX; if x is
a NaN they compute the value FP_ILOGBNAN; otherwise, they are equivalent to calling
-<!--page 237 indent 4-->
+<!--page 237 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ilogb functions return the exponent of x as a signed int value.
<p><b> Forward references</b>: the logb functions (<a href="#7.12.6.11">7.12.6.11</a>).
<a name="7.12.6.6" href="#7.12.6.6"><h5>7.12.6.6 The ldexp functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double ldexp(double x, int exp);
float ldexpf(float x, int exp);
long double ldexpl(long double x, int exp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ldexp functions multiply a floating-point number by an integral power of 2. A
range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ldexp functions return x x 2exp .
<a name="7.12.6.7" href="#7.12.6.7"><h5>7.12.6.7 The log functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log(double x);
float logf(float x);
long double logl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The log functions compute the base-e (natural) logarithm of x. A domain error occurs if
the argument is negative. A range error may occur if the argument is zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The log functions return loge x.
<a name="7.12.6.8" href="#7.12.6.8"><h5>7.12.6.8 The log10 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 238 indent 4-->
+<p><!--para 1 -->
+<!--page 238 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log10(double x);
float log10f(float x);
long double log10l(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The log10 functions compute the base-10 (common) logarithm of x. A domain error
occurs if the argument is negative. A range error may occur if the argument is zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The log10 functions return log10 x.
<a name="7.12.6.9" href="#7.12.6.9"><h5>7.12.6.9 The log1p functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log1p(double x);
float log1pf(float x);
long double log1pl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.<sup><a href="#note209"><b>209)</b></a></sup>
A domain error occurs if the argument is less than -1. A range error may occur if the
argument equals -1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The log1p functions return loge (1 + x).
<h6>footnotes</h6>
<a name="7.12.6.10" href="#7.12.6.10"><h5>7.12.6.10 The log2 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log2(double x);
float log2f(float x);
long double log2l(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The log2 functions compute the base-2 logarithm of x. A domain error occurs if the
argument is less than zero. A range error may occur if the argument is zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The log2 functions return log2 x.
-<!--page 239 indent 4-->
+<!--page 239 -->
<a name="7.12.6.11" href="#7.12.6.11"><h5>7.12.6.11 The logb functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double logb(double x);
float logbf(float x);
long double logbl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The logb functions extract the exponent of x, as a signed integer value in floating-point
format. If x is subnormal it is treated as though it were normalized; thus, for positive
finite x,
1 <= x x FLT_RADIX-logb(x) < FLT_RADIX</pre>
A domain error or range error may occur if the argument is zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The logb functions return the signed exponent of x.
<a name="7.12.6.12" href="#7.12.6.12"><h5>7.12.6.12 The modf functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double modf(double value, double *iptr);
float modff(float value, float *iptr);
long double modfl(long double value, long double *iptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The modf functions break the argument value into integral and fractional parts, each of
which has the same type and sign as the argument. They store the integral part (in
floating-point format) in the object pointed to by iptr.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The modf functions return the signed fractional part of value.
-<!--page 240 indent 4-->
+<!--page 240 -->
<a name="7.12.6.13" href="#7.12.6.13"><h5>7.12.6.13 The scalbn and scalbln functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double scalbn(double x, int n);
float scalblnf(float x, long int n);
long double scalblnl(long double x, long int n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The scalbn and scalbln functions compute x x FLT_RADIXn efficiently, not
normally by computing FLT_RADIXn explicitly. A range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The scalbn and scalbln functions return x x FLT_RADIXn .
<a name="7.12.7" href="#7.12.7"><h4>7.12.7 Power and absolute-value functions</h4></a>
<a name="7.12.7.1" href="#7.12.7.1"><h5>7.12.7.1 The cbrt functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cbrt(double x);
float cbrtf(float x);
long double cbrtl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cbrt functions compute the real cube root of x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cbrt functions return x1/3 .
<a name="7.12.7.2" href="#7.12.7.2"><h5>7.12.7.2 The fabs functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fabs(double x);
float fabsf(float x);
long double fabsl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fabs functions compute the absolute value of a floating-point number x.
-<!--page 241 indent 4-->
+<!--page 241 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fabs functions return | x |.
<a name="7.12.7.3" href="#7.12.7.3"><h5>7.12.7.3 The hypot functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double hypot(double x, double y);
float hypotf(float x, float y);
long double hypotl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The hypot functions compute the square root of the sum of the squares of x and y,
without undue overflow or underflow. A range error may occur.
-<p><!--para 3-->
+<p><!--para 3 -->
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The hypot functions return (sqrt)x2 + y2 .
<pre>
???
<a name="7.12.7.4" href="#7.12.7.4"><h5>7.12.7.4 The pow functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double pow(double x, double y);
float powf(float x, float y);
long double powl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The pow functions compute x raised to the power y. A domain error occurs if x is finite
and negative and y is finite and not an integer value. A range error may occur. A domain
error may occur if x is zero and y is zero. A domain error or range error may occur if x
is zero and y is less than zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The pow functions return xy .
<a name="7.12.7.5" href="#7.12.7.5"><h5>7.12.7.5 The sqrt functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 242 indent 4-->
+<p><!--para 1 -->
+<!--page 242 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sqrt(double x);
float sqrtf(float x);
long double sqrtl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sqrt functions compute the nonnegative square root of x. A domain error occurs if
the argument is less than zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sqrt functions return (sqrt)x.
<pre>
???
<a name="7.12.8.1" href="#7.12.8.1"><h5>7.12.8.1 The erf functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double erf(double x);
float erff(float x);
long double erfl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The erf functions compute the error function of x.
<h6>Returns</h6>
<pre>
<a name="7.12.8.2" href="#7.12.8.2"><h5>7.12.8.2 The erfc functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double erfc(double x);
float erfcf(float x);
long double erfcl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The erfc functions compute the complementary error function of x. A range error
occurs if x is too large.
<h6>Returns</h6>
2</pre>
-<!--page 243 indent 4-->
+<!--page 243 -->
<pre>
(sqrt)pi
???
<a name="7.12.8.3" href="#7.12.8.3"><h5>7.12.8.3 The lgamma functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double lgamma(double x);
float lgammaf(float x);
long double lgammal(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The lgamma functions compute the natural logarithm of the absolute value of gamma of
x. A range error occurs if x is too large. A range error may occur if x is a negative
integer or zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The lgamma functions return loge | (Gamma)(x) |.
<a name="7.12.8.4" href="#7.12.8.4"><h5>7.12.8.4 The tgamma functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tgamma(double x);
float tgammaf(float x);
long double tgammal(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tgamma functions compute the gamma function of x. A domain error or range error
may occur if x is a negative integer or zero. A range error may occur if the magnitude of
x is too large or too small.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tgamma functions return (Gamma)(x).
<a name="7.12.9" href="#7.12.9"><h4>7.12.9 Nearest integer functions</h4></a>
<a name="7.12.9.1" href="#7.12.9.1"><h5>7.12.9.1 The ceil functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double ceil(double x);
float ceilf(float x);
long double ceill(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ceil functions compute the smallest integer value not less than x.
-<!--page 244 indent 4-->
+<!--page 244 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ceil functions return ???x???, expressed as a floating-point number.
<a name="7.12.9.2" href="#7.12.9.2"><h5>7.12.9.2 The floor functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double floor(double x);
float floorf(float x);
long double floorl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The floor functions compute the largest integer value not greater than x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The floor functions return ???x???, expressed as a floating-point number.
<a name="7.12.9.3" href="#7.12.9.3"><h5>7.12.9.3 The nearbyint functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nearbyint(double x);
float nearbyintf(float x);
long double nearbyintl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The nearbyint functions round their argument to an integer value in floating-point
format, using the current rounding direction and without raising the ''inexact'' floating-
point exception.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The nearbyint functions return the rounded integer value.
<a name="7.12.9.4" href="#7.12.9.4"><h5>7.12.9.4 The rint functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double rint(double x);
float rintf(float x);
long double rintl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The rint functions differ from the nearbyint functions (<a href="#7.12.9.3">7.12.9.3</a>) only in that the
rint functions may raise the ''inexact'' floating-point exception if the result differs in
value from the argument.
-<!--page 245 indent 4-->
+<!--page 245 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The rint functions return the rounded integer value.
<a name="7.12.9.5" href="#7.12.9.5"><h5>7.12.9.5 The lrint and llrint functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
long int lrint(double x);
long long int llrintf(float x);
long long int llrintl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The lrint and llrint functions round their argument to the nearest integer value,
rounding according to the current rounding direction. If the rounded value is outside the
range of the return type, the numeric result is unspecified and a domain error or range
error may occur. *
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The lrint and llrint functions return the rounded integer value.
<a name="7.12.9.6" href="#7.12.9.6"><h5>7.12.9.6 The round functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double round(double x);
float roundf(float x);
long double roundl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The round functions round their argument to the nearest integer value in floating-point
format, rounding halfway cases away from zero, regardless of the current rounding
direction.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The round functions return the rounded integer value.
-<!--page 246 indent 4-->
+<!--page 246 -->
<a name="7.12.9.7" href="#7.12.9.7"><h5>7.12.9.7 The lround and llround functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
long int lround(double x);
long long int llroundf(float x);
long long int llroundl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The lround and llround functions round their argument to the nearest integer value,
rounding halfway cases away from zero, regardless of the current rounding direction. If
the rounded value is outside the range of the return type, the numeric result is unspecified
and a domain error or range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The lround and llround functions return the rounded integer value.
<a name="7.12.9.8" href="#7.12.9.8"><h5>7.12.9.8 The trunc functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double trunc(double x);
float truncf(float x);
long double truncl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The trunc functions round their argument to the integer value, in floating format,
nearest to but no larger in magnitude than the argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The trunc functions return the truncated integer value.
-<!--page 247 indent 4-->
+<!--page 247 -->
<a name="7.12.10" href="#7.12.10"><h4>7.12.10 Remainder functions</h4></a>
<a name="7.12.10.1" href="#7.12.10.1"><h5>7.12.10.1 The fmod functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmod(double x, double y);
float fmodf(float x, float y);
long double fmodl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fmod functions compute the floating-point remainder of x/y.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fmod functions return the value x - ny, for some integer n such that, if y is nonzero,
the result has the same sign as x and magnitude less than the magnitude of y. If y is zero,
whether a domain error occurs or the fmod functions return zero is implementation-
<a name="7.12.10.2" href="#7.12.10.2"><h5>7.12.10.2 The remainder functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remainder(double x, double y);
float remainderf(float x, float y);
long double remainderl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The remainder functions compute the remainder x REM y required by IEC 60559.<sup><a href="#note210"><b>210)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The remainder functions return x REM y. If y is zero, whether a domain error occurs
or the functions return zero is implementation defined.
-<!--page 248 indent 4-->
+<!--page 248 -->
<h6>footnotes</h6>
<p><small><a name="note210" href="#note210">210)</a> ''When y != 0, the remainder r = x REM y is defined regardless of the rounding mode by the
<a name="7.12.10.3" href="#7.12.10.3"><h5>7.12.10.3 The remquo functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remquo(double x, double y, int *quo);
long double remquol(long double x, long double y,
int *quo);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The remquo functions compute the same remainder as the remainder functions. In
the object pointed to by quo they store a value whose sign is the sign of x/y and whose
magnitude is congruent modulo 2n to the magnitude of the integral quotient of x/y, where
n is an implementation-defined integer greater than or equal to 3.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The remquo functions return x REM y. If y is zero, the value stored in the object
pointed to by quo is unspecified and whether a domain error occurs or the functions
return zero is implementation defined.
<a name="7.12.11.1" href="#7.12.11.1"><h5>7.12.11.1 The copysign functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double copysign(double x, double y);
float copysignf(float x, float y);
long double copysignl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The copysign functions produce a value with the magnitude of x and the sign of y.
They produce a NaN (with the sign of y) if x is a NaN. On implementations that
represent a signed zero but do not treat negative zero consistently in arithmetic
operations, the copysign functions regard the sign of zero as positive.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The copysign functions return a value with the magnitude of x and the sign of y.
-<!--page 249 indent 4-->
+<!--page 249 -->
<a name="7.12.11.2" href="#7.12.11.2"><h5>7.12.11.2 The nan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nan(const char *tagp);
float nanf(const char *tagp);
long double nanl(const char *tagp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The call nan("n-char-sequence") is equivalent to strtod("NAN(n-char-
sequence)", (char**) NULL); the call nan("") is equivalent to
strtod("NAN()", (char**) NULL). If tagp does not point to an n-char
NULL). Calls to nanf and nanl are equivalent to the corresponding calls to strtof
and strtold.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The nan functions return a quiet NaN, if available, with content indicated through tagp.
If the implementation does not support quiet NaNs, the functions return zero.
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.20.1.3">7.20.1.3</a>).
<a name="7.12.11.3" href="#7.12.11.3"><h5>7.12.11.3 The nextafter functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nextafter(double x, double y);
float nextafterf(float x, float y);
long double nextafterl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The nextafter functions determine the next representable value, in the type of the
function, after x in the direction of y, where x and y are first converted to the type of the
function.<sup><a href="#note211"><b>211)</b></a></sup> The nextafter functions return y if x equals y. A range error may occur
if the magnitude of x is the largest finite value representable in the type and the result is
infinite or not representable in the type.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The nextafter functions return the next representable value in the specified format
after x in the direction of y.
-<!--page 250 indent 4-->
+<!--page 250 -->
<h6>footnotes</h6>
<p><small><a name="note211" href="#note211">211)</a> The argument values are converted to the type of the function, even by a macro implementation of the
<a name="7.12.11.4" href="#7.12.11.4"><h5>7.12.11.4 The nexttoward functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nexttoward(double x, long double y);
float nexttowardf(float x, long double y);
long double nexttowardl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The nexttoward functions are equivalent to the nextafter functions except that the
second parameter has type long double and the functions return y converted to the
type of the function if x equals y.<sup><a href="#note212"><b>212)</b></a></sup>
<a name="7.12.12.1" href="#7.12.12.1"><h5>7.12.12.1 The fdim functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fdim(double x, double y);
float fdimf(float x, float y);
long double fdiml(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fdim functions determine the positive difference between their arguments:
<pre>
???x - y if x > y
???+0 if x <= y</pre>
A range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fdim functions return the positive difference value.
<a name="7.12.12.2" href="#7.12.12.2"><h5>7.12.12.2 The fmax functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmax(double x, double y);
-<!--page 251 indent 4-->
+<!--page 251 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fmax functions determine the maximum numeric value of their arguments.<sup><a href="#note213"><b>213)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fmax functions return the maximum numeric value of their arguments.
<h6>footnotes</h6>
<a name="7.12.12.3" href="#7.12.12.3"><h5>7.12.12.3 The fmin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmin(double x, double y);
float fminf(float x, float y);
long double fminl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fmin functions determine the minimum numeric value of their arguments.<sup><a href="#note214"><b>214)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fmin functions return the minimum numeric value of their arguments.
<h6>footnotes</h6>
<a name="7.12.13.1" href="#7.12.13.1"><h5>7.12.13.1 The fma functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fma(double x, double y, double z);
long double fmal(long double x, long double y,
long double z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fma functions compute (x x y) + z, rounded as one ternary operation: they compute
the value (as if) to infinite precision and round once to the result format, according to the
current rounding mode. A range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fma functions return (x x y) + z, rounded as one ternary operation.
-<!--page 252 indent 4-->
+<!--page 252 -->
<a name="7.12.14" href="#7.12.14"><h4>7.12.14 Comparison macros</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The relational and equality operators support the usual mathematical relationships
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
<a name="7.12.14.1" href="#7.12.14.1"><h5>7.12.14.1 The isgreater macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isgreater(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isgreater macro determines whether its first argument is greater than its second
argument. The value of isgreater(x, y) is always equal to (x) > (y); however,
unlike (x) > (y), isgreater(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isgreater macro returns the value of (x) > (y).
<a name="7.12.14.2" href="#7.12.14.2"><h5>7.12.14.2 The isgreaterequal macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isgreaterequal(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isgreaterequal macro determines whether its first argument is greater than or
equal to its second argument. The value of isgreaterequal(x, y) is always equal
to (x) >= (y); however, unlike (x) >= (y), isgreaterequal(x, y) does
-<!--page 253 indent 4-->
+<!--page 253 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isgreaterequal macro returns the value of (x) >= (y).
<a name="7.12.14.3" href="#7.12.14.3"><h5>7.12.14.3 The isless macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isless(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isless macro determines whether its first argument is less than its second
argument. The value of isless(x, y) is always equal to (x) < (y); however,
unlike (x) < (y), isless(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isless macro returns the value of (x) < (y).
<a name="7.12.14.4" href="#7.12.14.4"><h5>7.12.14.4 The islessequal macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int islessequal(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The islessequal macro determines whether its first argument is less than or equal to
its second argument. The value of islessequal(x, y) is always equal to
(x) <= (y); however, unlike (x) <= (y), islessequal(x, y) does not raise
the ''invalid'' floating-point exception when x and y are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The islessequal macro returns the value of (x) <= (y).
<a name="7.12.14.5" href="#7.12.14.5"><h5>7.12.14.5 The islessgreater macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int islessgreater(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The islessgreater macro determines whether its first argument is less than or
greater than its second argument. The islessgreater(x, y) macro is similar to
(x) < (y) || (x) > (y); however, islessgreater(x, y) does not raise
the ''invalid'' floating-point exception when x and y are unordered (nor does it evaluate x
and y twice).
-<!--page 254 indent 4-->
+<!--page 254 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The islessgreater macro returns the value of (x) < (y) || (x) > (y).
<a name="7.12.14.6" href="#7.12.14.6"><h5>7.12.14.6 The isunordered macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isunordered(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isunordered macro determines whether its arguments are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isunordered macro returns 1 if its arguments are unordered and 0 otherwise.
-<!--page 255 indent 4-->
+<!--page 255 -->
<a name="7.13" href="#7.13"><h3>7.13 Nonlocal jumps <setjmp.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.13"><setjmp.h></a> defines the macro setjmp, and declares one function and
one type, for bypassing the normal function call and return discipline.<sup><a href="#note216"><b>216)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
The type declared is
<pre>
jmp_buf</pre>
invocation of that block, were it called recursively. It does not include the state of the
floating-point status flags, of open files, or of any other component of the abstract
machine.
-<p><!--para 3-->
+<p><!--para 3 -->
It is unspecified whether setjmp is a macro or an identifier declared with external
linkage. If a macro definition is suppressed in order to access an actual function, or a
program defines an external identifier with the name setjmp, the behavior is undefined.
<a name="7.13.1.1" href="#7.13.1.1"><h5>7.13.1.1 The setjmp macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.13"><setjmp.h></a>
int setjmp(jmp_buf env);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The setjmp macro saves its calling environment in its jmp_buf argument for later use
by the longjmp function.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the return is from a direct invocation, the setjmp macro returns the value zero. If the
return is from a call to the longjmp function, the setjmp macro returns a nonzero
value.
Environmental limits
-<p><!--para 4-->
+<p><!--para 4 -->
An invocation of the setjmp macro shall appear only in one of the following contexts:
<ul>
<li> the entire controlling expression of a selection or iteration statement;
constant expression, with the resulting expression being the entire controlling
-<!--page 256 indent 4-->
+<!--page 256 -->
expression of a selection or iteration statement;
<li> the operand of a unary ! operator with the resulting expression being the entire
controlling expression of a selection or iteration statement; or
<li> the entire expression of an expression statement (possibly cast to void).
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
If the invocation appears in any other context, the behavior is undefined.
<a name="7.13.2" href="#7.13.2"><h4>7.13.2 Restore calling environment</h4></a>
<a name="7.13.2.1" href="#7.13.2.1"><h5>7.13.2.1 The longjmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.13"><setjmp.h></a>
void longjmp(jmp_buf env, int val);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The longjmp function restores the environment saved by the most recent invocation of
the setjmp macro in the same invocation of the program with the corresponding
jmp_buf argument. If there has been no such invocation, or if the function containing
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.
-<p><!--para 3-->
+<p><!--para 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
and have been changed between the setjmp invocation and longjmp call are
indeterminate.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
After longjmp is completed, program execution continues as if the corresponding
invocation of the setjmp macro had just returned the value specified by val. The
longjmp function cannot cause the setjmp macro to return the value 0; if val is 0,
the setjmp macro returns the value 1.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE The longjmp function that returns control back to the point of the setjmp invocation
might cause memory associated with a variable length array object to be squandered.
-<!--page 257 indent -1-->
-<!--page 258 indent 4-->
+<!--page 257 -->
+<!--page 258 -->
<pre>
#include <a href="#7.13"><setjmp.h></a>
jmp_buf buf;
</small>
<a name="7.14" href="#7.14"><h3>7.14 Signal handling <signal.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.14"><signal.h></a> declares a type and two functions and defines several macros,
for handling various signals (conditions that may be reported during program execution).
-<p><!--para 2-->
+<p><!--para 2 -->
The type defined is
<pre>
sig_atomic_t</pre>
which is the (possibly volatile-qualified) integer type of an object that can be accessed as
an atomic entity, even in the presence of asynchronous interrupts.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros defined are
<pre>
SIG_DFL
compare unequal to the address of any declarable function; and the following, which
expand to positive integer constant expressions with type int and distinct values that are
the signal numbers, each corresponding to the specified condition:
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
SIGABRT abnormal termination, such as is initiated by the abort function
SIGFPE an erroneous arithmetic operation, such as zero divide or an operation
-<!--page 259 indent 4-->
+<!--page 259 -->
<h6>footnotes</h6>
<p><small><a name="note219" href="#note219">219)</a> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>). The names of the signal numbers reflect the following terms
<a name="7.14.1.1" href="#7.14.1.1"><h5>7.14.1.1 The signal function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.14"><signal.h></a>
void (*signal(int sig, void (*func)(int)))(int);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The signal function chooses one of three ways in which receipt of the signal number
sig is to be subsequently handled. If the value of func is SIG_DFL, default handling
for that signal will occur. If the value of func is SIG_IGN, the signal will be ignored.
invocation of such a function because of a signal, or (recursively) of any further functions
called by that invocation (other than functions in the standard library), is called a signal
handler.
-<p><!--para 3-->
+<p><!--para 3 -->
When a signal occurs and func points to a function, it is implementation-defined
whether the equivalent of signal(sig, SIG_DFL); is executed or the
implementation prevents some implementation-defined set of signals (at least including
value of sig is SIGFPE, SIGILL, SIGSEGV, or any other implementation-defined
value corresponding to a computational exception, the behavior is undefined; otherwise
the program will resume execution at the point it was interrupted.
-<p><!--para 4-->
+<p><!--para 4 -->
If the signal occurs as the result of calling the abort or raise function, the signal
handler shall not call the raise function.
-<p><!--para 5-->
+<p><!--para 5 -->
If the signal occurs other than as the result of calling the abort or raise function, the
behavior is undefined if the signal handler refers to any object with static storage duration
other than by assigning a value to an object declared as volatile sig_atomic_t, or
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.<sup><a href="#note220"><b>220)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 6 -->
At program startup, the equivalent of
<pre>
signal(sig, SIG_IGN);</pre>
-<!--page 260 indent 4-->
+<!--page 260 -->
may be executed for some signals selected in an implementation-defined manner; the
equivalent of
<pre>
signal(sig, SIG_DFL);</pre>
is executed for all other signals defined by the implementation.
-<p><!--para 7-->
+<p><!--para 7 -->
The implementation shall behave as if no library function calls the signal function.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
If the request can be honored, the signal function returns the value of func for the
most recent successful call to signal for the specified signal sig. Otherwise, a value of
SIG_ERR is returned and a positive value is stored in errno.
<a name="7.14.2.1" href="#7.14.2.1"><h5>7.14.2.1 The raise function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.14"><signal.h></a>
int raise(int sig);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The raise function carries out the actions described in <a href="#7.14.1.1">7.14.1.1</a> for the signal sig. If a
signal handler is called, the raise function shall not return until after the signal handler
does.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The raise function returns zero if successful, nonzero if unsuccessful.
-<!--page 261 indent 4-->
+<!--page 261 -->
<a name="7.15" href="#7.15"><h3>7.15 Variable arguments <stdarg.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.15"><stdarg.h></a> declares a type and defines four macros, for advancing
through a list of arguments whose number and types are not known to the called function
when it is translated.
-<p><!--para 2-->
+<p><!--para 2 -->
A function may be called with a variable number of arguments of varying types. As
described in <a href="#6.9.1">6.9.1</a>, its parameter list contains one or more parameters. The rightmost
parameter plays a special role in the access mechanism, and will be designated parmN in
this description.
-<p><!--para 3-->
+<p><!--para 3 -->
The type declared is
<pre>
va_list</pre>
</small>
<a name="7.15.1" href="#7.15.1"><h4>7.15.1 Variable argument list access macros</h4></a>
-<p><!--para 1-->
+<p><!--para 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
identifiers declared with external linkage. If a macro definition is suppressed in order to
<a name="7.15.1.1" href="#7.15.1.1"><h5>7.15.1.1 The va_arg macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
type va_arg(va_list ap, type);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The va_arg macro expands to an expression that has the specified type and the value of
the next argument in the call. The parameter ap shall have been initialized by the
va_start or va_copy macro (without an intervening invocation of the va_end
-<!--page 262 indent 4-->
+<!--page 262 -->
macro for the same ap). Each invocation of the va_arg macro modifies ap so that the
values of successive arguments are returned in turn. The parameter type shall be a type
name specified such that the type of a pointer to an object that has the specified type can
<li> one type is pointer to void and the other is a pointer to a character type.
</ul>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The first invocation of the va_arg macro after that of the va_start macro returns the
value of the argument after that specified by parmN . Successive invocations return the
values of the remaining arguments in succession.
<a name="7.15.1.2" href="#7.15.1.2"><h5>7.15.1.2 The va_copy macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
void va_copy(va_list dest, va_list src);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The va_copy macro initializes dest as a copy of src, as if the va_start macro had
been applied to dest followed by the same sequence of uses of the va_arg macro as
had previously been used to reach the present state of src. Neither the va_copy nor
va_start macro shall be invoked to reinitialize dest without an intervening
invocation of the va_end macro for the same dest.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The va_copy macro returns no value.
<a name="7.15.1.3" href="#7.15.1.3"><h5>7.15.1.3 The va_end macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
void va_end(va_list ap);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The va_end macro facilitates a normal return from the function whose variable
argument list was referred to by the expansion of the va_start macro, or the function
containing the expansion of the va_copy macro, that initialized the va_list ap. The
va_end macro may modify ap so that it is no longer usable (without being reinitialized
-<!--page 263 indent 4-->
+<!--page 263 -->
by the va_start or va_copy macro). If there is no corresponding invocation of the
va_start or va_copy macro, or if the va_end macro is not invoked before the
return, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The va_end macro returns no value.
<a name="7.15.1.4" href="#7.15.1.4"><h5>7.15.1.4 The va_start macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
void va_start(va_list ap, parmN);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The va_start macro shall be invoked before any access to the unnamed arguments.
-<p><!--para 3-->
+<p><!--para 3 -->
The va_start macro initializes ap for subsequent use by the va_arg and va_end
macros. Neither the va_start nor va_copy macro shall be invoked to reinitialize ap
without an intervening invocation of the va_end macro for the same ap.
-<p><!--para 4-->
+<p><!--para 4 -->
The parameter parmN is the identifier of the rightmost parameter in the variable
parameter list in the function definition (the one just before the , ...). If the parameter
parmN is declared with the register storage class, with a function or array type, or
with a type that is not compatible with the type that results after application of the default
argument promotions, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The va_start macro returns no value.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 1 The function f1 gathers into an array a list of arguments that are pointers to strings (but not
more than MAXARGS arguments), then passes the array as a single argument to function f2. The number of
pointers is specified by the first argument to f1.
-<!--page 264 indent 4-->
+<!--page 264 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#define MAXARGS 31
<pre>
void f1(int, ...);</pre>
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 2 The function f3 is similar, but saves the status of the variable argument list after the
indicated number of arguments; after f2 has been called once with the whole list, the trailing part of the list
is gathered again and passed to function f4.
-<!--page 265 indent 4-->
+<!--page 265 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#define MAXARGS 31
}</pre>
<a name="7.16" href="#7.16"><h3>7.16 Boolean type and values <stdbool.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.16"><stdbool.h></a> defines four macros.
-<p><!--para 2-->
+<p><!--para 2 -->
The macro
<pre>
bool</pre>
expands to _Bool.
-<p><!--para 3-->
+<p><!--para 3 -->
The remaining three macros are suitable for use in #if preprocessing directives. They
are
<pre>
<pre>
__bool_true_false_are_defined</pre>
which expands to the integer constant 1.
-<p><!--para 4-->
+<p><!--para 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.<sup><a href="#note222"><b>222)</b></a></sup>
-<!--page 266 indent 4-->
+<!--page 266 -->
<h6>footnotes</h6>
<p><small><a name="note222" href="#note222">222)</a> See ''future library directions'' (<a href="#7.26.7">7.26.7</a>).
</small>
<a name="7.17" href="#7.17"><h3>7.17 Common definitions <stddef.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following types and macros are defined in the standard header <a href="#7.17"><stddef.h></a>. Some
are also defined in other headers, as noted in their respective subclauses.
-<p><!--para 2-->
+<p><!--para 2 -->
The types are
<pre>
ptrdiff_t</pre>
shall have a code value equal to its value when used as the lone character in an integer
character constant if an implementation does not define
__STDC_MB_MIGHT_NEQ_WC__.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros are
<pre>
NULL</pre>
then the expression &(t.member-designator) evaluates to an address constant. (If the
specified member is a bit-field, the behavior is undefined.)
Recommended practice
-<p><!--para 4-->
+<p><!--para 4 -->
The types used for size_t and ptrdiff_t should not have an integer conversion rank
greater than that of signed long int unless the implementation supports objects
large enough to make this necessary.
<p><b> Forward references</b>: localization (<a href="#7.11">7.11</a>).
-<!--page 267 indent 4-->
+<!--page 267 -->
<a name="7.18" href="#7.18"><h3>7.18 Integer types <stdint.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.18"><stdint.h></a> declares sets of integer types having specified widths, and
defines corresponding sets of macros.<sup><a href="#note223"><b>223)</b></a></sup> It also defines macros that specify limits of
integer types corresponding to types defined in other standard headers.
-<p><!--para 2-->
+<p><!--para 2 -->
Types are defined in the following categories:
<ul>
<li> integer types having certain exact widths;
<li> integer types having greatest width.
</ul>
(Some of these types may denote the same type.)
-<p><!--para 3-->
+<p><!--para 3 -->
Corresponding macros specify limits of the declared types and construct suitable
constants.
-<p><!--para 4-->
+<p><!--para 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
</small>
<a name="7.18.1" href="#7.18.1"><h4>7.18.1 Integer types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When typedef names differing only in the absence or presence of the initial u are defined,
they shall denote corresponding signed and unsigned types as described in <a href="#6.2.5">6.2.5</a>; an
implementation providing one of these corresponding types shall also provide the other.
-<p><!--para 2-->
+<p><!--para 2 -->
In the following descriptions, the symbol N represents an unsigned decimal integer with
no leading zeros (e.g., 8 or 24, but not 04 or 048).
-<!--page 268 indent 4-->
+<!--page 268 -->
<a name="7.18.1.1" href="#7.18.1.1"><h5>7.18.1.1 Exact-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The typedef name intN_t designates a signed integer type with width N , no padding
bits, and a two's complement representation. Thus, int8_t denotes a signed integer
type with a width of exactly 8 bits.
-<p><!--para 2-->
+<p><!--para 2 -->
The typedef name uintN_t designates an unsigned integer type with width N . Thus,
uint24_t denotes an unsigned integer type with a width of exactly 24 bits.
-<p><!--para 3-->
+<p><!--para 3 -->
These types are optional. However, if an implementation provides integer types with
widths of 8, 16, 32, or 64 bits, no padding bits, and (for the signed types) that have a
two's complement representation, it shall define the corresponding typedef names.
<a name="7.18.1.2" href="#7.18.1.2"><h5>7.18.1.2 Minimum-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The typedef name int_leastN_t designates a signed integer type with a width of at
least N , such that no signed integer type with lesser size has at least the specified width.
Thus, int_least32_t denotes a signed integer type with a width of at least 32 bits.
-<p><!--para 2-->
+<p><!--para 2 -->
The typedef name uint_leastN_t designates an unsigned integer type with a width
of at least N , such that no unsigned integer type with lesser size has at least the specified
width. Thus, uint_least16_t denotes an unsigned integer type with a width of at
least 16 bits.
-<p><!--para 3-->
+<p><!--para 3 -->
The following types are required:
<pre>
int_least8_t uint_least8_t
All other types of this form are optional.
<a name="7.18.1.3" href="#7.18.1.3"><h5>7.18.1.3 Fastest minimum-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 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.
-<p><!--para 2-->
+<p><!--para 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
type with a width of at least N .
-<!--page 269 indent 4-->
-<p><!--para 3-->
+<!--page 269 -->
+<p><!--para 3 -->
The following types are required:
<pre>
int_fast8_t uint_fast8_t
</small>
<a name="7.18.1.4" href="#7.18.1.4"><h5>7.18.1.4 Integer types capable of holding object pointers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following type designates a signed integer type with the property that any valid
pointer to void can be converted to this type, then converted back to pointer to void,
and the result will compare equal to the original pointer:
These types are optional.
<a name="7.18.1.5" href="#7.18.1.5"><h5>7.18.1.5 Greatest-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following type designates a signed integer type capable of representing any value of
any signed integer type:
<pre>
These types are required.
<a name="7.18.2" href="#7.18.2"><h4>7.18.2 Limits of specified-width integer types</h4></a>
-<p><!--para 1-->
+<p><!--para 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>.
-<p><!--para 2-->
+<p><!--para 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
-<!--page 270 indent 4-->
+<!--page 270 -->
the integer 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,
except where stated to be exactly the given value.
</small>
<a name="7.18.2.1" href="#7.18.2.1"><h5>7.18.2.1 Limits of exact-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum values of exact-width signed integer types
INTN_MIN exactly -(2 N -1 )
</ul>
<a name="7.18.2.2" href="#7.18.2.2"><h5>7.18.2.2 Limits of minimum-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum values of minimum-width signed integer types
INT_LEASTN_MIN -(2 N -1 - 1)
</ul>
<a name="7.18.2.3" href="#7.18.2.3"><h5>7.18.2.3 Limits of fastest minimum-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum values of fastest minimum-width signed integer types
INT_FASTN_MIN -(2 N -1 - 1)
</ul>
<a name="7.18.2.4" href="#7.18.2.4"><h5>7.18.2.4 Limits of integer types capable of holding object pointers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum value of pointer-holding signed integer type
<pre>
INTPTR_MIN -(215 - 1)</pre>
<li> maximum value of pointer-holding signed integer type
-<!--page 271 indent 4-->
+<!--page 271 -->
<pre>
INTPTR_MAX 215 - 1</pre>
<li> maximum value of pointer-holding unsigned integer type
</ul>
<a name="7.18.2.5" href="#7.18.2.5"><h5>7.18.2.5 Limits of greatest-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum value of greatest-width signed integer type
INTMAX_MIN -(263 - 1)
</ul>
<a name="7.18.3" href="#7.18.3"><h4>7.18.3 Limits of other integer types</h4></a>
-<p><!--para 1-->
+<p><!--para 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.
-<p><!--para 2-->
+<p><!--para 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
expression that is an object of the corresponding type converted according to the integer
-<!--page 272 indent 4-->
+<!--page 272 -->
WCHAR_MIN see below
WCHAR_MAX see below
<li> limits of wint_t
WINT_MIN see below
WINT_MAX see below
</ul>
-<p><!--para 3-->
+<p><!--para 3 -->
If sig_atomic_t (see <a href="#7.14">7.14</a>) is defined as a signed integer type, the value of
SIG_ATOMIC_MIN shall be no greater than -127 and the value of SIG_ATOMIC_MAX
shall be no less than 127; otherwise, sig_atomic_t is defined as an unsigned integer
type, and the value of SIG_ATOMIC_MIN shall be 0 and the value of
SIG_ATOMIC_MAX shall be no less than 255.
-<p><!--para 4-->
+<p><!--para 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.<sup><a href="#note229"><b>229)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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
</small>
<a name="7.18.4" href="#7.18.4"><h4>7.18.4 Macros for integer constants</h4></a>
-<p><!--para 1-->
+<p><!--para 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>.
-<p><!--para 2-->
+<p><!--para 2 -->
The argument in any instance of these macros shall be an unsuffixed integer constant (as
defined in <a href="#6.4.4.1">6.4.4.1</a>) with a value that does not exceed the limits for the corresponding type.
-<p><!--para 3-->
+<p><!--para 3 -->
Each invocation of one of these macros shall expand to an integer constant expression
suitable for use in #if preprocessing directives. The type of the expression shall have
the same type as would an expression of the corresponding type converted according to
-<!--page 273 indent 4-->
+<!--page 273 -->
<h6>footnotes</h6>
<p><small><a name="note230" href="#note230">230)</a> C++ implementations should define these macros only when __STDC_CONSTANT_MACROS is
</small>
<a name="7.18.4.1" href="#7.18.4.1"><h5>7.18.4.1 Macros for minimum-width integer constants</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The macro INTN_C(value) shall expand to an integer constant expression
corresponding to the type int_leastN_t. The macro UINTN_C(value) shall expand
to an integer constant expression corresponding to the type uint_leastN_t. For
then UINT64_C(0x123) might expand to the integer constant 0x123ULL.
<a name="7.18.4.2" href="#7.18.4.2"><h5>7.18.4.2 Macros for greatest-width integer constants</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following macro expands to an integer constant expression having the value specified
by its argument and the type intmax_t:
<pre>
INTMAX_C(value)</pre>
The following macro expands to an integer constant expression having the value specified
by its argument and the type uintmax_t:
-<!--page 274 indent 4-->
+<!--page 274 -->
<pre>
UINTMAX_C(value)</pre>
<a name="7.19" href="#7.19"><h3>7.19 Input/output <stdio.h></h3></a>
<a name="7.19.1" href="#7.19.1"><h4>7.19.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.19"><stdio.h></a> declares three types, several macros, and many functions for
performing input and output.
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are size_t (described in <a href="#7.17">7.17</a>);
<pre>
FILE</pre>
fpos_t</pre>
which is an object type other than an array type capable of recording all the information
needed to specify uniquely every position within a file.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros are NULL (described in <a href="#7.17">7.17</a>);
<pre>
_IOFBF
FILENAME_MAX</pre>
which expands to an integer constant expression that is the size needed for an array of
char large enough to hold the longest file name string that the implementation
-<!--page 275 indent 4-->
+<!--page 275 -->
guarantees can be opened;<sup><a href="#note231"><b>231)</b></a></sup>
<pre>
L_tmpnam</pre>
stdout</pre>
which are expressions of type ''pointer to FILE'' that point to the FILE objects
associated, respectively, with the standard error, input, and output streams.
-<p><!--para 4-->
+<p><!--para 4 -->
The header <a href="#7.24"><wchar.h></a> declares a number of functions useful for wide character input
and output. The wide character input/output functions described in that subclause
provide operations analogous to most of those described here, except that the
fundamental units internal to the program are wide characters. The external
representation (in the file) is a sequence of ''generalized'' multibyte characters, as
described further in <a href="#7.19.3">7.19.3</a>.
-<p><!--para 5-->
+<p><!--para 5 -->
The input/output functions are given the following collective terms:
<ul>
<li> The wide character input functions -- those functions described in <a href="#7.24">7.24</a> that perform
putwchar, fwprintf, wprintf, vfwprintf, and vwprintf.
-<!--page 276 indent 4-->
+<!--page 276 -->
<li> The wide character input/output functions -- the union of the ungetwc function, the
wide character input functions, and the wide character output functions.
<li> The byte input/output functions -- those functions described in this subclause that
</small>
<a name="7.19.2" href="#7.19.2"><h4>7.19.2 Streams</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Input and output, whether to or from physical devices such as terminals and tape drives,
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.<sup><a href="#note232"><b>232)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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
immediately preceded by space characters; and the last character is a new-line character.
Whether space characters that are written out immediately before a new-line character
appear when read in is implementation-defined.
-<p><!--para 3-->
+<p><!--para 3 -->
A binary stream is an ordered sequence of characters that can transparently record
internal data. Data read in from a binary stream shall compare equal to the data that were
earlier written out to that stream, under the same implementation. Such a stream may,
however, have an implementation-defined number of null characters appended to the end
of the stream.
-<p><!--para 4-->
+<p><!--para 4 -->
Each stream has an orientation. After a stream is associated with an external file, but
before any operations are performed on it, the stream is without orientation. Once a wide
character input/output function has been applied to a stream without orientation, the
-<!--page 277 indent 4-->
+<!--page 277 -->
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.)<sup><a href="#note233"><b>233)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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,
function can overwrite a partial multibyte character; any file contents beyond the
byte(s) written are henceforth indeterminate.
</ul>
-<p><!--para 6-->
+<p><!--para 6 -->
Each wide-oriented stream has an associated mbstate_t object that stores the current
parse state of the stream. A successful call to fgetpos stores a representation of the
value of this mbstate_t object as part of the value of the fpos_t object. A later
successful call to fsetpos using the same stored fpos_t value restores the value of
the associated mbstate_t object as well as the position within the controlled stream.
Environmental limits
-<p><!--para 7-->
+<p><!--para 7 -->
An implementation shall support text files with lines containing at least 254 characters,
including the terminating new-line character. The value of the macro BUFSIZ shall be at
least 256.
-<!--page 278 indent 4-->
+<!--page 278 -->
<h6>footnotes</h6>
<p><small><a name="note232" href="#note232">232)</a> An implementation need not distinguish between text streams and binary streams. In such an
</small>
<a name="7.19.3" href="#7.19.3"><h4>7.19.3 Files</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A stream is associated with an external file (which may be a physical device) by opening
a file, which may involve creating a new file. Creating an existing file causes its former
contents to be discarded, if necessary. If a file can support positioning requests (such as a
position indicator is initially positioned at the beginning or the end of the file. The file
position indicator is maintained by subsequent reads, writes, and positioning requests, to
facilitate an orderly progression through the file.
-<p><!--para 2-->
+<p><!--para 2 -->
Binary files are not truncated, except as defined in <a href="#7.19.5.3">7.19.5.3</a>. Whether a write on a text
stream causes the associated file to be truncated beyond that point is implementation-
defined.
-<p><!--para 3-->
+<p><!--para 3 -->
When a stream is unbuffered, characters are intended to appear from the source or at the
destination as soon as possible. Otherwise characters may be accumulated and
transmitted to or from the host environment as a block. When a stream is fully buffered,
when input is requested on a line buffered stream that requires the transmission of
characters from the host environment. Support for these characteristics is
implementation-defined, and may be affected via the setbuf and setvbuf functions.
-<p><!--para 4-->
+<p><!--para 4 -->
A file may be disassociated from a controlling stream by closing the file. Output streams
are flushed (any unwritten buffer contents are transmitted to the host environment) before
the stream is disassociated from the file. The value of a pointer to a FILE object is
indeterminate after the associated file is closed (including the standard text streams).
Whether a file of zero length (on which no characters have been written by an output
stream) actually exists is implementation-defined.
-<p><!--para 5-->
+<p><!--para 5 -->
The file may be subsequently reopened, by the same or another program execution, and
its contents reclaimed or modified (if it can be repositioned at its start). If the main
function returns to its original caller, or if the exit function is called, all open files are
closed (hence all output streams are flushed) before program termination. Other paths to
program termination, such as calling the abort function, need not close all files
properly.
-<p><!--para 6-->
+<p><!--para 6 -->
The address of the FILE object used to control a stream may be significant; a copy of a
FILE object need not serve in place of the original.
-<!--page 279 indent 5-->
-<p><!--para 7-->
+<!--page 279 -->
+<p><!--para 7 -->
At program startup, three text streams are predefined and need not be opened explicitly
<ul>
<li> standard input (for reading conventional input), standard output (for writing
opened, the standard error stream is not fully buffered; the standard input and standard
output streams are fully buffered if and only if the stream can be determined not to refer
to an interactive device.
-<p><!--para 8-->
+<p><!--para 8 -->
Functions that open additional (nontemporary) files require a file name, which is a string.
The rules for composing valid file names are implementation-defined. Whether the same
file can be simultaneously open multiple times is also implementation-defined.
-<p><!--para 9-->
+<p><!--para 9 -->
Although both text and binary wide-oriented streams are conceptually sequences of wide
characters, the external file associated with a wide-oriented stream is a sequence of
multibyte characters, generalized as follows:
encodings valid for use internal to the program).
<li> A file need not begin nor end in the initial shift state.<sup><a href="#note234"><b>234)</b></a></sup>
</ul>
-<p><!--para 10-->
+<p><!--para 10 -->
Moreover, the encodings used for multibyte characters may differ among files. Both the
nature and choice of such encodings are implementation-defined.
-<p><!--para 11-->
+<p><!--para 11 -->
The wide character input functions read multibyte characters from the stream and convert
them to wide characters as if they were read by successive calls to the fgetwc function.
Each conversion occurs as if by a call to the mbrtowc function, with the conversion state
described by the stream's own mbstate_t object. The byte input functions read
characters from the stream as if by successive calls to the fgetc function.
-<p><!--para 12-->
+<p><!--para 12 -->
The wide character output functions convert wide characters to multibyte characters and
write them to the stream as if they were written by successive calls to the fputwc
function. Each conversion occurs as if by a call to the wcrtomb function, with the
conversion state described by the stream's own mbstate_t object. The byte output
functions write characters to the stream as if by successive calls to the fputc function.
-<p><!--para 13-->
+<p><!--para 13 -->
In some cases, some of the byte input/output functions also perform conversions between
multibyte characters and wide characters. These conversions also occur as if by calls to
the mbrtowc and wcrtomb functions.
-<p><!--para 14-->
+<p><!--para 14 -->
An encoding error occurs if the character sequence presented to the underlying
mbrtowc function does not form a valid (generalized) multibyte character, or if the code
value passed to the underlying wcrtomb does not correspond to a valid (generalized)
-<!--page 280 indent 5-->
+<!--page 280 -->
multibyte character. The wide character input/output functions and the byte input/output
functions store the value of the macro EILSEQ in errno if and only if an encoding error
occurs.
Environmental limits
-<p><!--para 15-->
+<p><!--para 15 -->
The value of FOPEN_MAX shall be at least eight, including the three standard text
streams.
<p><b> Forward references</b>: the exit function (<a href="#7.20.4.3">7.20.4.3</a>), the fgetc function (<a href="#7.19.7.1">7.19.7.1</a>), the
<a name="7.19.4.1" href="#7.19.4.1"><h5>7.19.4.1 The remove function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int remove(const char *filename);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The remove function causes the file whose name is the string pointed to by filename
to be no longer accessible by that name. A subsequent attempt to open that file using that
name will fail, unless it is created anew. If the file is open, the behavior of the remove
function is implementation-defined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The remove function returns zero if the operation succeeds, nonzero if it fails.
<a name="7.19.4.2" href="#7.19.4.2"><h5>7.19.4.2 The rename function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int rename(const char *old, const char *new);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The rename function causes the file whose name is the string pointed to by old to be
henceforth known by the name given by the string pointed to by new. The file named
old is no longer accessible by that name. If a file named by the string pointed to by new
exists prior to the call to the rename function, the behavior is implementation-defined.
-<!--page 281 indent 4-->
+<!--page 281 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The rename function returns zero if the operation succeeds, nonzero if it fails,<sup><a href="#note235"><b>235)</b></a></sup> in
which case if the file existed previously it is still known by its original name.
<a name="7.19.4.3" href="#7.19.4.3"><h5>7.19.4.3 The tmpfile function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *tmpfile(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tmpfile function creates a temporary binary file that is different from any other
existing file and that will automatically be removed when it is closed or at program
termination. If the program terminates abnormally, whether an open temporary file is
removed is implementation-defined. The file is opened for update with "wb+" mode.
Recommended practice
-<p><!--para 3-->
+<p><!--para 3 -->
It should be possible to open at least TMP_MAX temporary files during the lifetime of the
program (this limit may be shared with tmpnam) and there should be no limit on the
number simultaneously open other than this limit and any limit on the number of open
files (FOPEN_MAX).
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The tmpfile function returns a pointer to the stream of the file that it created. If the file
cannot be created, the tmpfile function returns a null pointer.
<p><b> Forward references</b>: the fopen function (<a href="#7.19.5.3">7.19.5.3</a>).
<a name="7.19.4.4" href="#7.19.4.4"><h5>7.19.4.4 The tmpnam function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
char *tmpnam(char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tmpnam function generates a string that is a valid file name and that is not the same
as the name of an existing file.<sup><a href="#note236"><b>236)</b></a></sup> The function is potentially capable of generating
-<!--page 282 indent 4-->
+<!--page 282 -->
TMP_MAX different strings, but any or all of them may already be in use by existing files
and thus not be suitable return values.
-<p><!--para 3-->
+<p><!--para 3 -->
The tmpnam function generates a different string each time it is called.
-<p><!--para 4-->
+<p><!--para 4 -->
The implementation shall behave as if no library function calls the tmpnam function.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
If no suitable string can be generated, the tmpnam function returns a null pointer.
Otherwise, if the argument is a null pointer, the tmpnam function leaves its result in an
internal static object and returns a pointer to that object (subsequent calls to the tmpnam
to point to an array of at least L_tmpnam chars; the tmpnam function writes its result
in that array and returns the argument as its value.
Environmental limits
-<p><!--para 6-->
+<p><!--para 6 -->
The value of the macro TMP_MAX shall be at least 25.
<h6>footnotes</h6>
<a name="7.19.5.1" href="#7.19.5.1"><h5>7.19.5.1 The fclose function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fclose(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A successful call to the fclose function causes the stream pointed to by stream to be
flushed and the associated file to be closed. Any unwritten buffered data for the stream
are delivered to the host environment to be written to the file; any unread buffered data
and any buffer set by the setbuf or setvbuf function is disassociated from the stream
(and deallocated if it was automatically allocated).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fclose function returns zero if the stream was successfully closed, or EOF if any
errors were detected.
<a name="7.19.5.2" href="#7.19.5.2"><h5>7.19.5.2 The fflush function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 283 indent 4-->
+<p><!--para 1 -->
+<!--page 283 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fflush(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If stream points to an output stream or an update stream in which the most recent
operation was not input, the fflush function causes any unwritten data for that stream
to be delivered to the host environment to be written to the file; otherwise, the behavior is
undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
If stream is a null pointer, the fflush function performs this flushing action on all
streams for which the behavior is defined above.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The fflush function sets the error indicator for the stream and returns EOF if a write
error occurs, otherwise it returns zero.
<p><b> Forward references</b>: the fopen function (<a href="#7.19.5.3">7.19.5.3</a>).
<a name="7.19.5.3" href="#7.19.5.3"><h5>7.19.5.3 The fopen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *fopen(const char * restrict filename,
const char * restrict mode);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fopen function opens the file whose name is the string pointed to by filename,
and associates a stream with it.
-<p><!--para 3-->
+<p><!--para 3 -->
The argument mode points to a string. If the string is one of the following, the file is
open in the indicated mode. Otherwise, the behavior is undefined.<sup><a href="#note237"><b>237)</b></a></sup>
r open text file for reading
-<!--page 284 indent 4-->
+<!--page 284 -->
r+b or rb+ open binary file for update (reading and writing)
w+b or wb+ truncate to zero length or create binary file for update
a+b or ab+ append; open or create binary file for update, writing at end-of-file
-<p><!--para 4-->
+<p><!--para 4 -->
Opening a file with read mode ('r' as the first character in the mode argument) fails if
the file does not exist or cannot be read.
-<p><!--para 5-->
+<p><!--para 5 -->
Opening a file with append mode ('a' as the first character in the mode argument)
causes all subsequent writes to the file to be forced to the then current end-of-file,
regardless of intervening calls to the fseek function. In some implementations, opening
a binary file with append mode ('b' as the second or third character in the above list of
mode argument values) may initially position the file position indicator for the stream
beyond the last data written, because of null character padding.
-<p><!--para 6-->
+<p><!--para 6 -->
When a file is opened with update mode ('+' as the second or third character in the
above list of mode argument values), both input and output may be performed on the
associated stream. However, output shall not be directly followed by input without an
intervening call to a file positioning function, unless the input operation encounters end-
of-file. Opening (or creating) a text file with update mode may instead open (or create) a
binary stream in some implementations.
-<p><!--para 7-->
+<p><!--para 7 -->
When opened, a stream is fully buffered if and only if it can be determined not to refer to
an interactive device. The error and end-of-file indicators for the stream are cleared.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The fopen function returns a pointer to the object controlling the stream. If the open
operation fails, fopen returns a null pointer.
<p><b> Forward references</b>: file positioning functions (<a href="#7.19.9">7.19.9</a>).
<a name="7.19.5.4" href="#7.19.5.4"><h5>7.19.5.4 The freopen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
FILE *freopen(const char * restrict filename,
const char * restrict mode,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The freopen function opens the file whose name is the string pointed to by filename
and associates the stream pointed to by stream with it. The mode argument is used just
-<!--page 285 indent 4-->
+<!--page 285 -->
as in the fopen function.<sup><a href="#note238"><b>238)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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
permitted (if any), and under what circumstances.
-<p><!--para 4-->
+<p><!--para 4 -->
The freopen function first attempts to close any file that is associated with the specified
stream. Failure to close the file is ignored. The error and end-of-file indicators for the
stream are cleared.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The freopen function returns a null pointer if the open operation fails. Otherwise,
freopen returns the value of stream.
<a name="7.19.5.5" href="#7.19.5.5"><h5>7.19.5.5 The setbuf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
void setbuf(FILE * restrict stream,
char * restrict buf);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Except that it returns no value, the setbuf function is equivalent to the setvbuf
function invoked with the values _IOFBF for mode and BUFSIZ for size, or (if buf
is a null pointer), with the value _IONBF for mode.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The setbuf function returns no value.
<p><b> Forward references</b>: the setvbuf function (<a href="#7.19.5.6">7.19.5.6</a>).
<a name="7.19.5.6" href="#7.19.5.6"><h5>7.19.5.6 The setvbuf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int setvbuf(FILE * restrict stream,
-<!--page 286 indent 4-->
+<!--page 286 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The setvbuf function may be used only after the stream pointed to by stream has
been associated with an open file and before any other operation (other than an
unsuccessful call to setvbuf) is performed on the stream. The argument mode
allocated by the setvbuf function. The contents of the array at any time are
indeterminate.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The setvbuf function returns zero on success, or nonzero if an invalid value is given
for mode or if the request cannot be honored.
</small>
<a name="7.19.6" href="#7.19.6"><h4>7.19.6 Formatted input/output functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The formatted input/output functions shall behave as if there is a sequence point after the
actions associated with each specifier.<sup><a href="#note240"><b>240)</b></a></sup>
<a name="7.19.6.1" href="#7.19.6.1"><h5>7.19.6.1 The fprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fprintf(FILE * restrict stream,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fprintf function writes output to the stream pointed to by stream, under control
of the string pointed to by format that specifies how subsequent arguments are
converted for output. If there are insufficient arguments for the format, the behavior is
undefined. If the format is exhausted while arguments remain, the excess arguments are
evaluated (as always) but are otherwise ignored. The fprintf function returns when
the end of the format string is encountered.
-<p><!--para 3-->
+<p><!--para 3 -->
The format shall be a multibyte character sequence, beginning and ending in its initial
shift state. The format is composed of zero or more directives: ordinary multibyte
characters (not %), which are copied unchanged to the output stream; and conversion
-<!--page 287 indent 4-->
+<!--page 287 -->
specifications, each of which results in fetching zero or more subsequent arguments,
converting them, if applicable, according to the corresponding conversion specifier, and
then writing the result to the output stream.
-<p><!--para 4-->
+<p><!--para 4 -->
Each conversion specification is introduced by the character %. After the %, the following
appear in sequence:
<ul>
<li> An optional length modifier that specifies the size of the argument.
<li> A conversion specifier character that specifies the type of conversion to be applied.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
As noted above, a field width, or precision, or both, may be indicated by an asterisk. In
this case, an int argument supplies the field width or precision. The arguments
specifying field width, or precision, or both, shall appear (in that order) before the
argument (if any) to be converted. A negative field width argument is taken as a - flag
followed by a positive field width. A negative precision argument is taken as if the
precision were omitted.
-<p><!--para 6-->
+<p><!--para 6 -->
The flag characters and their meanings are:
- The result of the conversion is left-justified within the field. (It is right-justified if
<pre>
-<!--page 288 indent 4-->
+<!--page 288 -->
<pre>
specified.)<sup><a href="#note242"><b>242)</b></a></sup></pre>
space If the first character of a signed conversion is not a sign, or if a signed conversion
follows it.) For g and G conversions, trailing zeros are not removed from the
result. For other conversions, the behavior is undefined.</pre>
0 For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
-<p><!--para 7-->
+<p><!--para 7 -->
<pre>
(following any indication of sign or base) are used to pad to the field width rather
than performing space padding, except when converting an infinity or NaN. If the
long int or unsigned long int argument; that a following n
conversion specifier applies to a pointer to a long int argument; that a</pre>
-<!--page 289 indent 4-->
+<!--page 289 -->
<pre>
following c conversion specifier applies to a wint_t argument; that a
following s conversion specifier applies to a pointer to a wchar_t
applies to a long double argument.</pre>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
-<p><!--para 8-->
+<p><!--para 8 -->
The conversion specifiers and their meanings are:
d,i The int argument is converted to signed decimal in the style [-]dddd. The
<pre>
leading zeros. The default precision is 1. The result of converting a zero
value with a precision of zero is no characters.</pre>
o,u,x,X The unsigned int argument is converted to unsigned octal (o), unsigned
-<!--page 290 indent 0-->
+<!--page 290 -->
<pre>
decimal (u), or unsigned hexadecimal notation (x or X) in the style dddd; the
letters abcdef are used for x conversion and the letters ABCDEF for X
-- otherwise, the conversion is with style e (or E) and precision P - 1.
Finally, unless the # flag is used, any trailing zeros are removed from the</pre>
-<!--page 291 indent 0-->
+<!--page 291 -->
<pre>
fractional portion of the result and the decimal-point character is removed if
there is no fractional portion remaining.
element of an array of character type.<sup><a href="#note246"><b>246)</b></a></sup> Characters from the array are</pre>
-<!--page 292 indent 5-->
+<!--page 292 -->
<pre>
written up to (but not including) the terminating null character. If the
precision is specified, no more than that many bytes are written. If the
specification includes any flags, a field width, or a precision, the behavior is
undefined.</pre>
% A % character is written. No argument is converted. The complete
-<p><!--para 9-->
+<p><!--para 9 -->
<pre>
conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note248"><b>248)</b></a></sup> If any argument is
not the correct type for the corresponding conversion specification, the behavior is
undefined.
-<p><!--para 10-->
+<p><!--para 10 -->
In no case does a nonexistent or small field width cause truncation of a field; if the result
of a conversion is wider than the field width, the field is expanded to contain the
conversion result.
-<!--page 293 indent 5-->
-<p><!--para 11-->
+<!--page 293 -->
+<p><!--para 11 -->
For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
to a hexadecimal floating number with the given precision.
Recommended practice
-<p><!--para 12-->
+<p><!--para 12 -->
For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
representable in the given precision, the result should be one of the two adjacent numbers
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.
-<p><!--para 13-->
+<p><!--para 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.<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
of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that
the error should have a correct sign for the current rounding direction.
<h6>Returns</h6>
-<p><!--para 14-->
+<p><!--para 14 -->
The fprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
Environmental limits
-<p><!--para 15-->
+<p><!--para 15 -->
The number of characters that can be produced by any single conversion shall be at least
4095.
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE 1 To print a date and time in the form ''Sunday, July 3, 10:02'' followed by pi to five decimal
places:
<pre>
weekday, month, day, hour, min);
fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0));</pre>
-<p><!--para 17-->
+<p><!--para 17 -->
EXAMPLE 2 In this example, multibyte characters do not have a state-dependent encoding, and the
members of the extended character set that consist of more than one byte each consist of exactly two bytes,
the first of which is denoted here by a and the second by an uppercase letter.
-<!--page 294 indent 5-->
-<p><!--para 18-->
+<!--page 294 -->
+<p><!--para 18 -->
Given the following wide string with length seven,
<pre>
static wchar_t wstr[] = L" X Yabc Z W";</pre>
<a name="7.19.6.2" href="#7.19.6.2"><h5>7.19.6.2 The fscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fscanf(FILE * restrict stream,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fscanf function reads input from the stream pointed to by stream, under control
of the string pointed to by format that specifies the admissible input sequences and how
they are to be converted for assignment, using subsequent arguments as pointers to the
objects to receive the converted input. If there are insufficient arguments for the format,
the behavior is undefined. If the format is exhausted while arguments remain, the excess
arguments are evaluated (as always) but are otherwise ignored.
-<p><!--para 3-->
+<p><!--para 3 -->
The format shall be a multibyte character sequence, beginning and ending in its initial
shift state. The format is composed of zero or more directives: one or more white-space
characters, an ordinary multibyte character (neither % nor a white-space character), or a
<li> An optional assignment-suppressing character *.
<li> An optional decimal integer greater than zero that specifies the maximum field width
(in characters).
-<!--page 295 indent 5-->
+<!--page 295 -->
<li> An optional length modifier that specifies the size of the receiving object.
<li> A conversion specifier character that specifies the type of conversion to be applied.
</ul>
-<p><!--para 4-->
+<p><!--para 4 -->
The fscanf function executes each directive of the format in turn. If a directive fails, as
detailed below, the function returns. Failures are described as input failures (due to the
occurrence of an encoding error or the unavailability of input characters), or matching
failures (due to inappropriate input).
-<p><!--para 5-->
+<p><!--para 5 -->
A directive composed of white-space character(s) is executed by reading input up to the
first non-white-space character (which remains unread), or until no more characters can
be read.
-<p><!--para 6-->
+<p><!--para 6 -->
A directive that is an ordinary multibyte character is executed by reading the next
characters of the stream. If any of those characters differ from the ones composing the
directive, the directive fails and the differing and subsequent characters remain unread.
Similarly, if end-of-file, an encoding error, or a read error prevents a character from being
read, the directive fails.
-<p><!--para 7-->
+<p><!--para 7 -->
A directive that is a conversion specification defines a set of matching input sequences, as
described below for each specifier. A conversion specification is executed in the
following steps:
-<p><!--para 8-->
+<p><!--para 8 -->
Input white-space characters (as specified by the isspace function) are skipped, unless
the specification includes a [, c, or n specifier.<sup><a href="#note250"><b>250)</b></a></sup>
-<p><!--para 9-->
+<p><!--para 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.<sup><a href="#note251"><b>251)</b></a></sup>
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.
-<p><!--para 10-->
+<p><!--para 10 -->
Except in the case of a % specifier, the input item (or, in the case of a %n directive, the
count of input characters) is converted to a type appropriate to the conversion specifier. If
the input item is not a matching sequence, the execution of the directive fails: this
does not have an appropriate type, or if the result of the conversion cannot be represented
-<!--page 296 indent 5-->
+<!--page 296 -->
in the object, the behavior is undefined.
-<p><!--para 11-->
+<p><!--para 11 -->
The length modifiers and their meanings are:
hh Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
<pre>
applies to an argument with type pointer to long double.</pre>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
-<p><!--para 12-->
+<p><!--para 12 -->
The conversion specifiers and their meanings are:
d Matches an optionally signed decimal integer, whose format is the same as
<pre>
for the base argument. The corresponding argument shall be a pointer to
signed integer.</pre>
i Matches an optionally signed integer, whose format is the same as expected
-<!--page 297 indent 0-->
+<!--page 297 -->
<pre>
for the subject sequence of the strtol function with the value 0 for the
base argument. The corresponding argument shall be a pointer to signed
If an l length modifier is present, the input shall be a sequence of multibyte</pre>
-<!--page 298 indent 0-->
+<!--page 298 -->
<pre>
characters that begins in the initial shift state. Each multibyte character is
converted to a wide character as if by a call to the mbrtowc function, with
second where the first character is a ^, nor the last character, the behavior is
implementation-defined.</pre>
p Matches an implementation-defined set of sequences, which should be the
-<!--page 299 indent 5-->
+<!--page 299 -->
<pre>
same as the set of sequences that may be produced by the %p conversion of
the fprintf function. The corresponding argument shall be a pointer to a
but one is consumed. If the conversion specification includes an assignment-
suppressing character or a field width, the behavior is undefined.</pre>
% Matches a single % character; no conversion or assignment occurs. The
-<p><!--para 13-->
+<p><!--para 13 -->
<pre>
complete conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note253"><b>253)</b></a></sup>
-<p><!--para 14-->
+<p><!--para 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.
-<p><!--para 15-->
+<p><!--para 15 -->
Trailing white space (including new-line characters) is left unread unless matched by a
directive. The success of literal matches and suppressed assignments is not directly
determinable other than via the %n directive.
<h6>Returns</h6>
-<p><!--para 16-->
+<p><!--para 16 -->
The fscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the function returns the number of input items
assigned, which can be fewer than provided for, or even zero, in the event of an early
matching failure.
-<p><!--para 17-->
+<p><!--para 17 -->
EXAMPLE 1 The call:
<pre>
#include <a href="#7.19"><stdio.h></a>
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
-<p><!--para 18-->
+<p><!--para 18 -->
EXAMPLE 2 The call:
<pre>
#include <a href="#7.19"><stdio.h></a>
-<!--page 300 indent 5-->
+<!--page 300 -->
<pre>
56789 0123 56a72</pre>
will assign to i the value 56 and to x the value 789.0, will skip 0123, and will assign to name the
sequence 56\0. The next character read from the input stream will be a.
-<p><!--para 19-->
+<p><!--para 19 -->
EXAMPLE 3 To accept repeatedly from stdin a quantity, a unit of measure, and an item name:
-<p><!--para 20-->
+<p><!--para 20 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
/* ... */
count = 0; // "100e" fails to match "%f"
count = EOF;</pre>
-<p><!--para 21-->
+<p><!--para 21 -->
EXAMPLE 4 In:
<pre>
#include <a href="#7.19"><stdio.h></a>
the value 123 is assigned to d1 and the value 3 to n1. Because %n can never get an input failure the value
of 3 is also assigned to n2. The value of d2 is not affected. The value 1 is assigned to i.
-<p><!--para 22-->
+<p><!--para 22 -->
EXAMPLE 5 In these examples, multibyte characters do have a state-dependent encoding, and the
members of the extended character set that consist of more than one byte each consist of exactly two bytes,
the first of which is denoted here by a and the second by an uppercase letter, but are only recognized as
such when in the alternate shift state. The shift sequences are denoted by (uparrow) and (downarrow), in which the first causes
entry into the alternate shift state.
-<p><!--para 23-->
+<p><!--para 23 -->
After the call:
-<!--page 301 indent 5-->
+<!--page 301 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
/* ... */
a(uparrow) X Y(downarrow) bc</pre>
str will contain (uparrow) X Y(downarrow)\0 assuming that none of the bytes of the shift sequences (or of the multibyte
characters, in the more general case) appears to be a single-byte white-space character.
-<p><!--para 24-->
+<p><!--para 24 -->
In contrast, after the call:
<pre>
#include <a href="#7.19"><stdio.h></a>
fscanf(stdin, "a%ls", wstr);</pre>
with the same input line, wstr will contain the two wide characters that correspond to X and Y and a
terminating null wide character.
-<p><!--para 25-->
+<p><!--para 25 -->
However, the call:
<pre>
#include <a href="#7.19"><stdio.h></a>
fscanf(stdin, "a(uparrow) X(downarrow)%ls", wstr);</pre>
with the same input line will return zero due to a matching failure against the (downarrow) sequence in the format
string.
-<p><!--para 26-->
+<p><!--para 26 -->
Assuming that the first byte of the multibyte character X is the same as the first byte of the multibyte
character Y, after the call:
<pre>
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.20.1.3">7.20.1.3</a>), the
strtol, strtoll, strtoul, and strtoull functions (<a href="#7.20.1.4">7.20.1.4</a>), conversion state
(<a href="#7.24.6">7.24.6</a>), the wcrtomb function (<a href="#7.24.6.3.3">7.24.6.3.3</a>).
-<!--page 302 indent 4-->
+<!--page 302 -->
<h6>footnotes</h6>
<p><small><a name="note250" href="#note250">250)</a> These white-space characters are not counted against a specified field width.
<a name="7.19.6.3" href="#7.19.6.3"><h5>7.19.6.3 The printf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int printf(const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The printf function is equivalent to fprintf with the argument stdout interposed
before the arguments to printf.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The printf function returns the number of characters transmitted, or a negative value if
an output or encoding error occurred.
<a name="7.19.6.4" href="#7.19.6.4"><h5>7.19.6.4 The scanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int scanf(const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The scanf function is equivalent to fscanf with the argument stdin interposed
before the arguments to scanf.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The scanf function returns the value of the macro EOF if an input failure occurs before
any conversion. Otherwise, the scanf function returns the number of input items
assigned, which can be fewer than provided for, or even zero, in the event of an early
<a name="7.19.6.5" href="#7.19.6.5"><h5>7.19.6.5 The snprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int snprintf(char * restrict s, size_t n,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The snprintf function is equivalent to fprintf, except that the output is written into
an array (specified by argument s) rather than to a stream. If n is zero, nothing is written,
and s may be a null pointer. Otherwise, output characters beyond the n-1st are
discarded rather than being written to the array, and a null character is written at the end
of the characters actually written into the array. If copying takes place between objects
that overlap, the behavior is undefined.
-<!--page 303 indent 4-->
+<!--page 303 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The snprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
value if an encoding error occurred. Thus, the null-terminated output has been
<a name="7.19.6.6" href="#7.19.6.6"><h5>7.19.6.6 The sprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int sprintf(char * restrict s,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sprintf function is equivalent to fprintf, except that the output is written into
an array (specified by the argument s) rather than to a stream. A null character is written
at the end of the characters written; it is not counted as part of the returned value. If
copying takes place between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sprintf function returns the number of characters written in the array, not
counting the terminating null character, or a negative value if an encoding error occurred.
<a name="7.19.6.7" href="#7.19.6.7"><h5>7.19.6.7 The sscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int sscanf(const char * restrict s,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sscanf function is equivalent to fscanf, except that input is obtained from a
string (specified by the argument s) rather than from a stream. Reaching the end of the
string is equivalent to encountering end-of-file for the fscanf function. If copying
takes place between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the sscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-<!--page 304 indent 4-->
+<!--page 304 -->
<a name="7.19.6.8" href="#7.19.6.8"><h5>7.19.6.8 The vfprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vfprintf function is equivalent to fprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfprintf function does not invoke the
va_end macro.<sup><a href="#note254"><b>254)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vfprintf function returns the number of characters transmitted, or a negative
value if an output or encoding error occurred.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The following shows the use of the vfprintf function in a general error-reporting routine.
<pre>
#include <a href="#7.15"><stdarg.h></a>
-<!--page 305 indent 4-->
+<!--page 305 -->
<h6>footnotes</h6>
<p><small><a name="note254" href="#note254">254)</a> As the functions vfprintf, vfscanf, vprintf, vscanf, vsnprintf, vsprintf, and
<a name="7.19.6.9" href="#7.19.6.9"><h5>7.19.6.9 The vfscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vfscanf function is equivalent to fscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfscanf function does not invoke the
va_end macro.254)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vfscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vfscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
<a name="7.19.6.10" href="#7.19.6.10"><h5>7.19.6.10 The vprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vprintf(const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vprintf function is equivalent to printf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vprintf function does not invoke the
va_end macro.254)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
-<!--page 306 indent 4-->
+<!--page 306 -->
<a name="7.19.6.11" href="#7.19.6.11"><h5>7.19.6.11 The vscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
int vscanf(const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vscanf function is equivalent to scanf, with the variable argument list replaced
by arg, which shall have been initialized by the va_start macro (and possibly
subsequent va_arg calls). The vscanf function does not invoke the va_end
macro.254)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
<a name="7.19.6.12" href="#7.19.6.12"><h5>7.19.6.12 The vsnprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vsnprintf function is equivalent to snprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsnprintf function does not invoke the
va_end macro.254) If copying takes place between objects that overlap, the behavior is
undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vsnprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
value if an encoding error occurred. Thus, the null-terminated output has been
completely written if and only if the returned value is nonnegative and less than n.
-<!--page 307 indent 4-->
+<!--page 307 -->
<a name="7.19.6.13" href="#7.19.6.13"><h5>7.19.6.13 The vsprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vsprintf function is equivalent to sprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsprintf function does not invoke the
va_end macro.254) If copying takes place between objects that overlap, the behavior is
undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vsprintf function returns the number of characters written in the array, not
counting the terminating null character, or a negative value if an encoding error occurred.
<a name="7.19.6.14" href="#7.19.6.14"><h5>7.19.6.14 The vsscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vsscanf function is equivalent to sscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsscanf function does not invoke the
va_end macro.254)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vsscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vsscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-<!--page 308 indent 4-->
+<!--page 308 -->
<a name="7.19.7" href="#7.19.7"><h4>7.19.7 Character input/output functions</h4></a>
<a name="7.19.7.1" href="#7.19.7.1"><h5>7.19.7.1 The fgetc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fgetc(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next character is present, the fgetc function obtains that character as an unsigned
char converted to an int and advances the associated file position indicator for the
stream (if defined).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetc function returns EOF. Otherwise, the
fgetc function returns the next character from the input stream pointed to by stream.
<a name="7.19.7.2" href="#7.19.7.2"><h5>7.19.7.2 The fgets function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
char *fgets(char * restrict s, int n,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fgets function reads at most one less than the number of characters specified by n
from the stream pointed to by stream into the array pointed to by s. No additional
characters are read after a new-line character (which is retained) or after end-of-file. A
null character is written immediately after the last character read into the array.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fgets function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
null pointer is returned. If a read error occurs during the operation, the array contents are
-<!--page 309 indent 4-->
+<!--page 309 -->
<a name="7.19.7.3" href="#7.19.7.3"><h5>7.19.7.3 The fputc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fputc(int c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fputc function writes the character specified by c (converted to an unsigned
char) to the output stream pointed to by stream, at the position indicated by the
associated file position indicator for the stream (if defined), and advances the indicator
appropriately. If the file cannot support positioning requests, or if the stream was opened
with append mode, the character is appended to the output stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fputc function returns the character written. If a write error occurs, the error
indicator for the stream is set and fputc returns EOF.
<a name="7.19.7.4" href="#7.19.7.4"><h5>7.19.7.4 The fputs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fputs(const char * restrict s,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fputs function writes the string pointed to by s to the stream pointed to by
stream. The terminating null character is not written.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fputs function returns EOF if a write error occurs; otherwise it returns a
nonnegative value.
<a name="7.19.7.5" href="#7.19.7.5"><h5>7.19.7.5 The getc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int getc(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getc function is equivalent to fgetc, except that if it is implemented as a macro, it
may evaluate stream more than once, so the argument should never be an expression
with side effects.
-<!--page 310 indent 4-->
+<!--page 310 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The getc function returns the next character from the input stream pointed to by
stream. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
getc returns EOF. If a read error occurs, the error indicator for the stream is set and
<a name="7.19.7.6" href="#7.19.7.6"><h5>7.19.7.6 The getchar function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int getchar(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getchar function is equivalent to getc with the argument stdin.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The getchar function returns the next character from the input stream pointed to by
stdin. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
getchar returns EOF. If a read error occurs, the error indicator for the stream is set and
<a name="7.19.7.7" href="#7.19.7.7"><h5>7.19.7.7 The gets function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
char *gets(char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The gets function reads characters from the input stream pointed to by stdin, into the
array pointed to by s, until end-of-file is encountered or a new-line character is read.
Any new-line character is discarded, and a null character is written immediately after the
last character read into the array.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The gets function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
null pointer is returned. If a read error occurs during the operation, the array contents are
indeterminate and a null pointer is returned.
<p><b> Forward references</b>: future library directions (<a href="#7.26.9">7.26.9</a>).
-<!--page 311 indent 4-->
+<!--page 311 -->
<a name="7.19.7.8" href="#7.19.7.8"><h5>7.19.7.8 The putc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int putc(int c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The putc function is equivalent to fputc, except that if it is implemented as a macro, it
may evaluate stream more than once, so that argument should never be an expression
with side effects.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The putc function returns the character written. If a write error occurs, the error
indicator for the stream is set and putc returns EOF.
<a name="7.19.7.9" href="#7.19.7.9"><h5>7.19.7.9 The putchar function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int putchar(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The putchar function is equivalent to putc with the second argument stdout.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The putchar function returns the character written. If a write error occurs, the error
indicator for the stream is set and putchar returns EOF.
<a name="7.19.7.10" href="#7.19.7.10"><h5>7.19.7.10 The puts function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int puts(const char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The puts function writes the string pointed to by s to the stream pointed to by stdout,
and appends a new-line character to the output. The terminating null character is not
written.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The puts function returns EOF if a write error occurs; otherwise it returns a nonnegative
value.
-<!--page 312 indent 4-->
+<!--page 312 -->
<a name="7.19.7.11" href="#7.19.7.11"><h5>7.19.7.11 The ungetc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int ungetc(int c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ungetc function pushes the character specified by c (converted to an unsigned
char) back onto the input stream pointed to by stream. Pushed-back characters will be
returned by subsequent reads on that stream in the reverse order of their pushing. A
successful intervening call (with the stream pointed to by stream) to a file positioning
function (fseek, fsetpos, or rewind) discards any pushed-back characters for the
stream. The external storage corresponding to the stream is unchanged.
-<p><!--para 3-->
+<p><!--para 3 -->
One character of pushback is guaranteed. If the ungetc function is called too many
times on the same stream without an intervening read or file positioning operation on that
stream, the operation may fail.
-<p><!--para 4-->
+<p><!--para 4 -->
If the value of c equals that of the macro EOF, the operation fails and the input stream is
unchanged.
-<p><!--para 5-->
+<p><!--para 5 -->
A successful call to the ungetc function clears the end-of-file indicator for the stream.
The value of the file position indicator for the stream after reading or discarding all
pushed-back characters shall be the same as it was before the characters were pushed
the ungetc function; if its value was zero before a call, it is indeterminate after the
call.<sup><a href="#note256"><b>256)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The ungetc function returns the character pushed back after conversion, or EOF if the
operation fails.
<p><b> Forward references</b>: file positioning functions (<a href="#7.19.9">7.19.9</a>).
-<!--page 313 indent 4-->
+<!--page 313 -->
<h6>footnotes</h6>
<p><small><a name="note256" href="#note256">256)</a> See ''future library directions'' (<a href="#7.26.9">7.26.9</a>).
<a name="7.19.8.1" href="#7.19.8.1"><h5>7.19.8.1 The fread function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
size_t fread(void * restrict ptr,
size_t size, size_t nmemb,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fread function reads, into the array pointed to by ptr, up to nmemb elements
whose size is specified by size, from the stream pointed to by stream. For each
object, size calls are made to the fgetc function and the results stored, in the order
read. If an error occurs, the resulting value of the file position indicator for the stream is
indeterminate. If a partial element is read, its value is indeterminate.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fread function returns the number of elements successfully read, which may be
less than nmemb if a read error or end-of-file is encountered. If size or nmemb is zero,
fread returns zero and the contents of the array and the state of the stream remain
<a name="7.19.8.2" href="#7.19.8.2"><h5>7.19.8.2 The fwrite function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
size_t fwrite(const void * restrict ptr,
size_t size, size_t nmemb,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fwrite function writes, from the array pointed to by ptr, up to nmemb elements
whose size is specified by size, to the stream pointed to by stream. For each object,
size calls are made to the fputc function, taking the values (in order) from an array of
stream (if defined) is advanced by the number of characters successfully written. If an
error occurs, the resulting value of the file position indicator for the stream is
indeterminate.
-<!--page 314 indent 4-->
+<!--page 314 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fwrite function returns the number of elements successfully written, which will be
less than nmemb only if a write error is encountered. If size or nmemb is zero,
fwrite returns zero and the state of the stream remains unchanged.
<a name="7.19.9.1" href="#7.19.9.1"><h5>7.19.9.1 The fgetpos function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fgetpos(FILE * restrict stream,
fpos_t * restrict pos);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fgetpos function stores the current values of the parse state (if any) and file
position indicator for the stream pointed to by stream in the object pointed to by pos.
The values stored contain unspecified information usable by the fsetpos function for
repositioning the stream to its position at the time of the call to the fgetpos function.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If successful, the fgetpos function returns zero; on failure, the fgetpos function
returns nonzero and stores an implementation-defined positive value in errno.
<p><b> Forward references</b>: the fsetpos function (<a href="#7.19.9.3">7.19.9.3</a>).
<a name="7.19.9.2" href="#7.19.9.2"><h5>7.19.9.2 The fseek function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fseek(FILE *stream, long int offset, int whence);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fseek function sets the file position indicator for the stream pointed to by stream.
If a read or write error occurs, the error indicator for the stream is set and fseek fails.
-<p><!--para 3-->
+<p><!--para 3 -->
For a binary stream, the new position, measured in characters from the beginning of the
file, is obtained by adding offset to the position specified by whence. The specified
position is the beginning of the file if whence is SEEK_SET, the current value of the file
position indicator if SEEK_CUR, or end-of-file if SEEK_END. A binary stream need not
meaningfully support fseek calls with a whence value of SEEK_END.
-<p><!--para 4-->
+<p><!--para 4 -->
For a text stream, either offset shall be zero, or offset shall be a value returned by
an earlier successful call to the ftell function on a stream associated with the same file
and whence shall be SEEK_SET.
-<!--page 315 indent 4-->
-<p><!--para 5-->
+<!--page 315 -->
+<p><!--para 5 -->
After determining the new position, a successful call to the fseek function undoes any
effects of the ungetc function on the stream, clears the end-of-file indicator for the
stream, and then establishes the new position. After a successful fseek call, the next
operation on an update stream may be either input or output.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The fseek function returns nonzero only for a request that cannot be satisfied.
<p><b> Forward references</b>: the ftell function (<a href="#7.19.9.4">7.19.9.4</a>).
<a name="7.19.9.3" href="#7.19.9.3"><h5>7.19.9.3 The fsetpos function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int fsetpos(FILE *stream, const fpos_t *pos);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fsetpos function sets the mbstate_t object (if any) and file position indicator
for the stream pointed to by stream according to the value of the object pointed to by
pos, which shall be a value obtained from an earlier successful call to the fgetpos
function on a stream associated with the same file. If a read or write error occurs, the
error indicator for the stream is set and fsetpos fails.
-<p><!--para 3-->
+<p><!--para 3 -->
A successful call to the fsetpos function undoes any effects of the ungetc function
on the stream, clears the end-of-file indicator for the stream, and then establishes the new
parse state and position. After a successful fsetpos call, the next operation on an
update stream may be either input or output.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If successful, the fsetpos function returns zero; on failure, the fsetpos function
returns nonzero and stores an implementation-defined positive value in errno.
<a name="7.19.9.4" href="#7.19.9.4"><h5>7.19.9.4 The ftell function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
long int ftell(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ftell function obtains the current value of the file position indicator for the stream
pointed to by stream. For a binary stream, the value is the number of characters from
the beginning of the file. For a text stream, its file position indicator contains unspecified
information, usable by the fseek function for returning the file position indicator for the
stream to its position at the time of the ftell call; the difference between two such
return values is not necessarily a meaningful measure of the number of characters written
-<!--page 316 indent 4-->
+<!--page 316 -->
or read.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If successful, the ftell function returns the current value of the file position indicator
for the stream. On failure, the ftell function returns -1L and stores an
implementation-defined positive value in errno.
<a name="7.19.9.5" href="#7.19.9.5"><h5>7.19.9.5 The rewind function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
void rewind(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The rewind function sets the file position indicator for the stream pointed to by
stream to the beginning of the file. It is equivalent to
<pre>
(void)fseek(stream, 0L, SEEK_SET)</pre>
except that the error indicator for the stream is also cleared.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The rewind function returns no value.
<a name="7.19.10" href="#7.19.10"><h4>7.19.10 Error-handling functions</h4></a>
<a name="7.19.10.1" href="#7.19.10.1"><h5>7.19.10.1 The clearerr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
void clearerr(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The clearerr function clears the end-of-file and error indicators for the stream pointed
to by stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The clearerr function returns no value.
-<!--page 317 indent 4-->
+<!--page 317 -->
<a name="7.19.10.2" href="#7.19.10.2"><h5>7.19.10.2 The feof function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int feof(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feof function tests the end-of-file indicator for the stream pointed to by stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feof function returns nonzero if and only if the end-of-file indicator is set for
stream.
<a name="7.19.10.3" href="#7.19.10.3"><h5>7.19.10.3 The ferror function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
int ferror(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ferror function tests the error indicator for the stream pointed to by stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ferror function returns nonzero if and only if the error indicator is set for
stream.
<a name="7.19.10.4" href="#7.19.10.4"><h5>7.19.10.4 The perror function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
void perror(const char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The perror function maps the error number in the integer expression errno to an
error message. It writes a sequence of characters to the standard error stream thus: first
(if s is not a null pointer and the character pointed to by s is not the null character), the
message string followed by a new-line character. The contents of the error message
strings are the same as those returned by the strerror function with argument errno.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The perror function returns no value.
<p><b> Forward references</b>: the strerror function (<a href="#7.21.6.2">7.21.6.2</a>).
-<!--page 318 indent 4-->
+<!--page 318 -->
<a name="7.20" href="#7.20"><h3>7.20 General utilities <stdlib.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.20"><stdlib.h></a> declares five types and several functions of general utility, and
defines several macros.<sup><a href="#note257"><b>257)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are size_t and wchar_t (both described in <a href="#7.17">7.17</a>),
<pre>
div_t</pre>
<pre>
lldiv_t</pre>
which is a structure type that is the type of the value returned by the lldiv function.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>);
<pre>
EXIT_FAILURE</pre>
-<!--page 319 indent 4-->
+<!--page 319 -->
<h6>footnotes</h6>
<p><small><a name="note257" href="#note257">257)</a> See ''future library directions'' (<a href="#7.26.10">7.26.10</a>).
</small>
<a name="7.20.1" href="#7.20.1"><h4>7.20.1 Numeric conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions atof, atoi, atol, and atoll need not affect the value of the integer
expression errno on an error. If the value of the result cannot be represented, the
behavior is undefined.
<a name="7.20.1.1" href="#7.20.1.1"><h5>7.20.1.1 The atof function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
double atof(const char *nptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atof function converts the initial portion of the string pointed to by nptr to
double representation. Except for the behavior on error, it is equivalent to
<pre>
strtod(nptr, (char **)NULL)</pre>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atof function returns the converted value.
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.20.1.3">7.20.1.3</a>).
<a name="7.20.1.2" href="#7.20.1.2"><h5>7.20.1.2 The atoi, atol, and atoll functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int atoi(const char *nptr);
long int atol(const char *nptr);
long long int atoll(const char *nptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atoi, atol, and atoll functions convert the initial portion of the string pointed
to by nptr to int, long int, and long long int representation, respectively.
Except for the behavior on error, they are equivalent to
atol: strtol(nptr, (char **)NULL, 10)
atoll: strtoll(nptr, (char **)NULL, 10)</pre>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atoi, atol, and atoll functions return the converted value.
<p><b> Forward references</b>: the strtol, strtoll, strtoul, and strtoull functions
(<a href="#7.20.1.4">7.20.1.4</a>).
-<!--page 320 indent 4-->
+<!--page 320 -->
<a name="7.20.1.3" href="#7.20.1.3"><h5>7.20.1.3 The strtod, strtof, and strtold functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
double strtod(const char * restrict nptr,
long double strtold(const char * restrict nptr,
char ** restrict endptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strtod, strtof, and strtold functions convert the initial portion of the string
pointed to by nptr to double, float, and long double representation,
respectively. First, they decompose the input string into three parts: an initial, possibly
and a final string of one or more unrecognized characters, including the terminating null
character of the input string. Then, they attempt to convert the subject sequence to a
floating-point number, and return the result.
-<p><!--para 3-->
+<p><!--para 3 -->
The expected form of the subject sequence is an optional plus or minus sign, then one of
the following:
<ul>
The subject sequence is defined as the longest initial subsequence of the input string,
starting with the first non-white-space character, that is of the expected form. The subject
sequence contains no characters if the input string is not of the expected form.
-<p><!--para 4-->
+<p><!--para 4 -->
If the subject sequence has the expected form for a floating-point number, the sequence of
characters starting with the first digit or the decimal-point character (whichever occurs
first) is interpreted as a floating constant according to the rules of <a href="#6.4.4.2">6.4.4.2</a>, except that the
-<!--page 321 indent 4-->
+<!--page 321 -->
decimal-point character is used in place of a period, and that if neither an exponent part
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
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.
-<p><!--para 5-->
+<p><!--para 5 -->
If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the
value resulting from the conversion is correctly rounded.
-<p><!--para 6-->
+<p><!--para 6 -->
In other than the "C" locale, additional locale-specific subject sequence forms may be
accepted.
-<p><!--para 7-->
+<p><!--para 7 -->
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
Recommended practice
-<p><!--para 8-->
+<p><!--para 8 -->
If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
the result is not exactly representable, the result should be one of the two numbers in the
appropriate internal format that are adjacent to the hexadecimal floating source value,
with the extra stipulation that the error should have a correct sign for the current rounding
direction.
-<p><!--para 9-->
+<p><!--para 9 -->
If the subject sequence has the decimal form and at most DECIMAL_DIG (defined in
<a href="#7.7"><float.h></a>) significant digits, the result should be correctly rounded. If the subject
sequence D has the decimal form and more than DECIMAL_DIG significant digits,
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
-<!--page 322 indent 5-->
+<!--page 322 -->
stipulation that the error with respect to D should have a correct sign for the current
rounding direction.<sup><a href="#note260"><b>260)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
The functions return the converted value, if any. If no conversion could be performed,
zero is returned. If the correct value is outside the range of representable values, plus or
minus HUGE_VAL, HUGE_VALF, or HUGE_VALL is returned (according to the return
<a name="7.20.1.4" href="#7.20.1.4"><h5>7.20.1.4 The strtol, strtoll, strtoul, and strtoull functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
long int strtol(
char ** restrict endptr,
int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strtol, strtoll, strtoul, and strtoull functions convert the initial
portion of the string pointed to by nptr to long int, long long int, unsigned
long int, and unsigned long long int representation, respectively. First,
white-space characters (as specified by the isspace function), a subject sequence
-<!--page 323 indent 4-->
+<!--page 323 -->
resembling an integer represented in some radix determined by the value of base, and a
final string of one or more unrecognized characters, including the terminating null
character of the input string. Then, they attempt to convert the subject sequence to an
integer, and return the result.
-<p><!--para 3-->
+<p><!--para 3 -->
If the value of base is zero, the expected form of the subject sequence is that of an
integer constant as described in <a href="#6.4.4.1">6.4.4.1</a>, optionally preceded by a plus or minus sign, but
not including an integer suffix. If the value of base is between 2 and 36 (inclusive), the
ascribed the values 10 through 35; only letters and digits whose ascribed values are less
than that of base are permitted. If the value of base is 16, the characters 0x or 0X may
optionally precede the sequence of letters and digits, following the sign if present.
-<p><!--para 4-->
+<p><!--para 4 -->
The subject sequence is defined as the longest initial subsequence of the input string,
starting with the first non-white-space character, that is of the expected form. The subject
sequence contains no characters if the input string is empty or consists entirely of white
space, or if the first non-white-space character is other than a sign or a permissible letter
or digit.
-<p><!--para 5-->
+<p><!--para 5 -->
If the subject sequence has the expected form and the value of base is zero, the sequence
of characters starting with the first digit is interpreted as an integer constant according to
the rules of <a href="#6.4.4.1">6.4.4.1</a>. If the subject sequence has the expected form and the value of base
as given above. If the subject sequence begins with a minus sign, the value resulting from
the conversion is negated (in the return type). A pointer to the final string is stored in the
object pointed to by endptr, provided that endptr is not a null pointer.
-<p><!--para 6-->
+<p><!--para 6 -->
In other than the "C" locale, additional locale-specific subject sequence forms may be
accepted.
-<p><!--para 7-->
+<p><!--para 7 -->
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The strtol, strtoll, strtoul, and strtoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
is outside the range of representable values, LONG_MIN, LONG_MAX, LLONG_MIN,
LLONG_MAX, ULONG_MAX, or ULLONG_MAX is returned (according to the return type
and sign of the value, if any), and the value of the macro ERANGE is stored in errno.
-<!--page 324 indent 4-->
+<!--page 324 -->
<a name="7.20.2" href="#7.20.2"><h4>7.20.2 Pseudo-random sequence generation functions</h4></a>
<a name="7.20.2.1" href="#7.20.2.1"><h5>7.20.2.1 The rand function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int rand(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The rand function computes a sequence of pseudo-random integers in the range 0 to
RAND_MAX.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the rand function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The rand function returns a pseudo-random integer.
Environmental limits
-<p><!--para 5-->
+<p><!--para 5 -->
The value of the RAND_MAX macro shall be at least 32767.
<a name="7.20.2.2" href="#7.20.2.2"><h5>7.20.2.2 The srand function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void srand(unsigned int seed);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The srand function uses the argument as a seed for a new sequence of pseudo-random
numbers to be returned by subsequent calls to rand. If srand is then called with the
same seed value, the sequence of pseudo-random numbers shall be repeated. If rand is
called before any calls to srand have been made, the same sequence shall be generated
as when srand is first called with a seed value of 1.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the srand function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The srand function returns no value.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE The following functions define a portable implementation of rand and srand.
-<!--page 325 indent 4-->
+<!--page 325 -->
<pre>
static unsigned long int next = 1;
int rand(void) // RAND_MAX assumed to be 32767
<a name="7.20.3" href="#7.20.3"><h4>7.20.3 Memory management functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The order and contiguity of storage allocated by successive calls to the calloc,
malloc, and realloc functions is unspecified. The pointer returned if the allocation
succeeds is suitably aligned so that it may be assigned to a pointer to any type of object
<a name="7.20.3.1" href="#7.20.3.1"><h5>7.20.3.1 The calloc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void *calloc(size_t nmemb, size_t size);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The calloc function allocates space for an array of nmemb objects, each of whose size
is size. The space is initialized to all bits zero.<sup><a href="#note261"><b>261)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The calloc function returns either a null pointer or a pointer to the allocated space.
<h6>footnotes</h6>
<a name="7.20.3.2" href="#7.20.3.2"><h5>7.20.3.2 The free function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void free(void *ptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The free function causes the space pointed to by ptr to be deallocated, that is, made
available for further allocation. If ptr is a null pointer, no action occurs. Otherwise, if
the argument does not match a pointer earlier returned by the calloc, malloc, or
-<!--page 326 indent 4-->
+<!--page 326 -->
realloc function, or if the space has been deallocated by a call to free or realloc,
the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The free function returns no value.
<a name="7.20.3.3" href="#7.20.3.3"><h5>7.20.3.3 The malloc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void *malloc(size_t size);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The malloc function allocates space for an object whose size is specified by size and
whose value is indeterminate.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The malloc function returns either a null pointer or a pointer to the allocated space.
<a name="7.20.3.4" href="#7.20.3.4"><h5>7.20.3.4 The realloc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void *realloc(void *ptr, size_t size);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The realloc function deallocates the old object pointed to by ptr and returns a
pointer to a new object that has the size specified by size. The contents of the new
object shall be the same as that of the old object prior to deallocation, up to the lesser of
the new and old sizes. Any bytes in the new object beyond the size of the old object have
indeterminate values.
-<p><!--para 3-->
+<p><!--para 3 -->
If ptr is a null pointer, the realloc function behaves like the malloc function for the
specified size. Otherwise, if ptr does not match a pointer earlier returned by the
calloc, malloc, or realloc function, or if the space has been deallocated by a call
to the free or realloc function, the behavior is undefined. If memory for the new
object cannot be allocated, the old object is not deallocated and its value is unchanged.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The realloc function returns a pointer to the new object (which may have the same
value as a pointer to the old object), or a null pointer if the new object could not be
allocated.
-<!--page 327 indent 4-->
+<!--page 327 -->
<a name="7.20.4" href="#7.20.4"><h4>7.20.4 Communication with the environment</h4></a>
<a name="7.20.4.1" href="#7.20.4.1"><h5>7.20.4.1 The abort function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void abort(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The abort function causes abnormal program termination to occur, unless the signal
SIGABRT is being caught and the signal handler does not return. Whether open streams
with unwritten buffered data are flushed, open streams are closed, or temporary files are
unsuccessful termination is returned to the host environment by means of the function
call raise(SIGABRT).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The abort function does not return to its caller.
<a name="7.20.4.2" href="#7.20.4.2"><h5>7.20.4.2 The atexit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int atexit(void (*func)(void));</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atexit function registers the function pointed to by func, to be called without
arguments at normal program termination.
Environmental limits
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall support the registration of at least 32 functions.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The atexit function returns zero if the registration succeeds, nonzero if it fails.
<p><b> Forward references</b>: the exit function (<a href="#7.20.4.3">7.20.4.3</a>).
<a name="7.20.4.3" href="#7.20.4.3"><h5>7.20.4.3 The exit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void exit(int status);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The exit function causes normal program termination to occur. If more than one call to
the exit function is executed by a program, the behavior is undefined.
-<!--page 328 indent 4-->
-<p><!--para 3-->
+<!--page 328 -->
+<p><!--para 3 -->
First, all functions registered by the atexit function are called, in the reverse order of
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.
-<p><!--para 4-->
+<p><!--para 4 -->
Next, all open streams with unwritten buffered data are flushed, all open streams are
closed, and all files created by the tmpfile function are removed.
-<p><!--para 5-->
+<p><!--para 5 -->
Finally, control is returned to the host environment. If the value of status is zero or
EXIT_SUCCESS, an implementation-defined form of the status successful termination is
returned. If the value of status is EXIT_FAILURE, an implementation-defined form
of the status unsuccessful termination is returned. Otherwise the status returned is
implementation-defined.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The exit function cannot return to its caller.
<h6>footnotes</h6>
<a name="7.20.4.4" href="#7.20.4.4"><h5>7.20.4.4 The _Exit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void _Exit(int status);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The _Exit function causes normal program termination to occur and control to be
returned to the host environment. No functions registered by the atexit function or
signal handlers registered by the signal function are called. The status returned to the
Whether open streams with unwritten buffered data are flushed, open streams are closed,
or temporary files are removed is implementation-defined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The _Exit function cannot return to its caller.
-<!--page 329 indent 4-->
+<!--page 329 -->
<a name="7.20.4.5" href="#7.20.4.5"><h5>7.20.4.5 The getenv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
char *getenv(const char *name);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getenv function searches an environment list, provided by the host environment,
for a string that matches the string pointed to by name. The set of environment names
and the method for altering the environment list are implementation-defined.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the getenv function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The getenv function returns a pointer to a string associated with the matched list
member. The string pointed to shall not be modified by the program, but may be
overwritten by a subsequent call to the getenv function. If the specified name cannot
<a name="7.20.4.6" href="#7.20.4.6"><h5>7.20.4.6 The system function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int system(const char *string);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If string is a null pointer, the system function determines whether the host
environment has a command processor. If string is not a null pointer, the system
function passes the string pointed to by string to that command processor to be
executed in a manner which the implementation shall document; this might then cause the
program calling system to behave in a non-conforming manner or to terminate.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a null pointer, the system function returns nonzero only if a
command processor is available. If the argument is not a null pointer, and the system
function does return, it returns an implementation-defined value.
-<!--page 330 indent 4-->
+<!--page 330 -->
<a name="7.20.5" href="#7.20.5"><h4>7.20.5 Searching and sorting utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
These utilities make use of a comparison function to search or sort arrays of unspecified
type. Where an argument declared as size_t nmemb specifies the length of the array
for a function, nmemb can have the value zero on a call to that function; the comparison
function is not called, a search finds no matching element, and sorting performs no
rearrangement. Pointer arguments on such a call shall still have valid values, as described
in <a href="#7.1.4">7.1.4</a>.
-<p><!--para 2-->
+<p><!--para 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.<sup><a href="#note263"><b>263)</b></a></sup> The first argument when called from bsearch
shall equal key.
-<p><!--para 3-->
+<p><!--para 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
alter the contents of any individual element.
-<p><!--para 4-->
+<p><!--para 4 -->
When the same objects (consisting of size bytes, irrespective of their current positions
in the array) are passed more than once to the comparison function, the results shall be
consistent with one another. That is, for qsort they shall define a total ordering on the
array, and for bsearch the same object shall always compare the same way with the
key.
-<p><!--para 5-->
+<p><!--para 5 -->
A sequence point occurs immediately before and immediately after each call to the
comparison function, and also between any call to the comparison function and any
movement of the objects passed as arguments to that call.
<a name="7.20.5.1" href="#7.20.5.1"><h5>7.20.5.1 The bsearch function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void *bsearch(const void *key, const void *base,
size_t nmemb, size_t size,
int (*compar)(const void *, const void *));</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The bsearch function searches an array of nmemb objects, the initial element of which
is pointed to by base, for an element that matches the object pointed to by key. The
-<!--page 331 indent 4-->
+<!--page 331 -->
size of each element of the array is specified by size.
-<p><!--para 3-->
+<p><!--para 3 -->
The comparison function pointed to by compar is called with two arguments that point
to the key object and to an array element, in that order. The function shall return an
integer less than, equal to, or greater than zero if the key object is considered,
shall consist of: all the elements that compare less than, all the elements that compare
equal to, and all the elements that compare greater than the key object, in that order.<sup><a href="#note264"><b>264)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The bsearch function returns a pointer to a matching element of the array, or a null
pointer if no match is found. If two elements compare as equal, which element is
matched is unspecified.
<a name="7.20.5.2" href="#7.20.5.2"><h5>7.20.5.2 The qsort function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
void qsort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *));</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The qsort function sorts an array of nmemb objects, the initial element of which is
pointed to by base. The size of each object is specified by size.
-<p><!--para 3-->
+<p><!--para 3 -->
The contents of the array are sorted into ascending order according to a comparison
function pointed to by compar, which is called with two arguments that point to the
objects being compared. The function shall return an integer less than, equal to, or
greater than zero if the first argument is considered to be respectively less than, equal to,
or greater than the second.
-<p><!--para 4-->
+<p><!--para 4 -->
If two elements compare as equal, their order in the resulting sorted array is unspecified.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The qsort function returns no value.
-<!--page 332 indent 4-->
+<!--page 332 -->
<a name="7.20.6" href="#7.20.6"><h4>7.20.6 Integer arithmetic functions</h4></a>
<a name="7.20.6.1" href="#7.20.6.1"><h5>7.20.6.1 The abs, labs and llabs functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int abs(int j);
long int labs(long int j);
long long int llabs(long long int j);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The abs, labs, and llabs functions compute the absolute value of an integer j. If the
result cannot be represented, the behavior is undefined.<sup><a href="#note265"><b>265)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The abs, labs, and llabs, functions return the absolute value.
<h6>footnotes</h6>
<a name="7.20.6.2" href="#7.20.6.2"><h5>7.20.6.2 The div, ldiv, and lldiv functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
div_t div(int numer, int denom);
ldiv_t ldiv(long int numer, long int denom);
lldiv_t lldiv(long long int numer, long long int denom);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The div, ldiv, and lldiv, functions compute numer / denom and numer %
denom in a single operation.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The div, ldiv, and lldiv functions return a structure of type div_t, ldiv_t, and
lldiv_t, respectively, comprising both the quotient and the remainder. The structures
shall contain (in either order) the members quot (the quotient) and rem (the remainder),
-<!--page 333 indent 4-->
+<!--page 333 -->
<a name="7.20.7" href="#7.20.7"><h4>7.20.7 Multibyte/wide character conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior of the multibyte character functions is affected by the LC_CTYPE category
of the current locale. For a state-dependent encoding, each function is placed into its
initial conversion state by a call for which its character pointer argument, s, is a null
<a name="7.20.7.1" href="#7.20.7.1"><h5>7.20.7.1 The mblen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int mblen(const char *s, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is not a null pointer, the mblen function determines the number of bytes contained
in the multibyte character pointed to by s. Except that the conversion state of the
mbtowc function is not affected, it is equivalent to
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
mbtowc((wchar_t *)0, s, n);</pre>
The implementation shall behave as if no library function calls the mblen function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If s is a null pointer, the mblen function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
not a null pointer, the mblen function either returns 0 (if s points to the null character),
-<!--page 334 indent 4-->
+<!--page 334 -->
<a name="7.20.7.2" href="#7.20.7.2"><h5>7.20.7.2 The mbtowc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int mbtowc(wchar_t * restrict pwc,
const char * restrict s,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is not a null pointer, the mbtowc function inspects at most n bytes beginning with
the byte pointed to by s to determine the number of bytes needed to complete the next
multibyte character (including any shift sequences). If the function determines that the
corresponding wide character and then, if pwc is not a null pointer, stores that value in
the object pointed to by pwc. If the corresponding wide character is the null wide
character, the function is left in the initial conversion state.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the mbtowc function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If s is a null pointer, the mbtowc function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
not a null pointer, the mbtowc function either returns 0 (if s points to the null character),
or returns the number of bytes that are contained in the converted multibyte character (if
the next n or fewer bytes form a valid multibyte character), or returns -1 (if they do not
form a valid multibyte character).
-<p><!--para 5-->
+<p><!--para 5 -->
In no case will the value returned be greater than n or the value of the MB_CUR_MAX
macro.
<a name="7.20.7.3" href="#7.20.7.3"><h5>7.20.7.3 The wctomb function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
int wctomb(char *s, wchar_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wctomb function determines the number of bytes needed to represent the multibyte
character corresponding to the wide character given by wc (including any shift
sequences), and stores the multibyte character representation in the array whose first
are stored. If wc is a null wide character, a null byte is stored, preceded by any shift
sequence needed to restore the initial shift state, and the function is left in the initial
conversion state.
-<!--page 335 indent 4-->
-<p><!--para 3-->
+<!--page 335 -->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the wctomb function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If s is a null pointer, the wctomb function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
not a null pointer, the wctomb function returns -1 if the value of wc does not correspond
to a valid multibyte character, or returns the number of bytes that are contained in the
multibyte character corresponding to the value of wc.
-<p><!--para 5-->
+<p><!--para 5 -->
In no case will the value returned be greater than the value of the MB_CUR_MAX macro.
<a name="7.20.8" href="#7.20.8"><h4>7.20.8 Multibyte/wide string conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior of the multibyte string functions is affected by the LC_CTYPE category of
the current locale.
<a name="7.20.8.1" href="#7.20.8.1"><h5>7.20.8.1 The mbstowcs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mbstowcs function converts a sequence of multibyte characters that begins in the
initial shift state from the array pointed to by s into a sequence of corresponding wide
characters and stores not more than n wide characters into the array pointed to by pwcs.
character) will be examined or converted. Each multibyte character is converted as if by
a call to the mbtowc function, except that the conversion state of the mbtowc function is
not affected.
-<p><!--para 3-->
+<p><!--para 3 -->
No more than n elements will be modified in the array pointed to by pwcs. If copying
takes place between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If an invalid multibyte character is encountered, the mbstowcs function returns
(size_t)(-1). Otherwise, the mbstowcs function returns the number of array
elements modified, not including a terminating null wide character, if any.<sup><a href="#note267"><b>267)</b></a></sup>
-<!--page 336 indent 4-->
+<!--page 336 -->
<h6>footnotes</h6>
<p><small><a name="note267" href="#note267">267)</a> The array will not be null-terminated if the value returned is n.
<a name="7.20.8.2" href="#7.20.8.2"><h5>7.20.8.2 The wcstombs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.20"><stdlib.h></a>
size_t wcstombs(char * restrict s,
const wchar_t * restrict pwcs,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcstombs function converts a sequence of wide characters from the array pointed
to by pwcs into a sequence of corresponding multibyte characters that begins in the
initial shift state, and stores these multibyte characters into the array pointed to by s,
stopping if a multibyte character would exceed the limit of n total bytes or if a null
character is stored. Each wide character is converted as if by a call to the wctomb
function, except that the conversion state of the wctomb function is not affected.
-<p><!--para 3-->
+<p><!--para 3 -->
No more than n bytes will be modified in the array pointed to by s. If copying takes place
between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If a wide character is encountered that does not correspond to a valid multibyte character,
the wcstombs function returns (size_t)(-1). Otherwise, the wcstombs function
returns the number of bytes modified, not including a terminating null character, if
any.267)
-<!--page 337 indent 4-->
+<!--page 337 -->
<a name="7.21" href="#7.21"><h3>7.21 String handling <string.h></h3></a>
<a name="7.21.1" href="#7.21.1"><h4>7.21.1 String function conventions</h4></a>
-<p><!--para 1-->
+<p><!--para 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.<sup><a href="#note268"><b>268)</b></a></sup> The type is size_t and the macro is NULL (both described in
<a href="#7.17">7.17</a>). Various methods are used for determining the lengths of the arrays, but in all cases
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.
-<p><!--para 2-->
+<p><!--para 2 -->
Where an argument declared as size_t n specifies the length of the array for a
function, n can have the value zero on a call to that function. Unless explicitly stated
otherwise in the description of a particular function in this subclause, pointer arguments
function that locates a character finds no occurrence, a function that compares two
character sequences returns zero, and a function that copies characters copies zero
characters.
-<p><!--para 3-->
+<p><!--para 3 -->
For all functions in this subclause, each character shall be interpreted as if it had the type
unsigned char (and therefore every possible object representation is valid and has a
different value).
<a name="7.21.2.1" href="#7.21.2.1"><h5>7.21.2.1 The memcpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
void *memcpy(void * restrict s1,
const void * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memcpy function copies n characters from the object pointed to by s2 into the
object pointed to by s1. If copying takes place between objects that overlap, the behavior
is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memcpy function returns the value of s1.
-<!--page 338 indent 4-->
+<!--page 338 -->
<a name="7.21.2.2" href="#7.21.2.2"><h5>7.21.2.2 The memmove function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
void *memmove(void *s1, const void *s2, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memmove function copies n characters from the object pointed to by s2 into the
object pointed to by s1. Copying takes place as if the n characters from the object
pointed to by s2 are first copied into a temporary array of n characters that does not
overlap the objects pointed to by s1 and s2, and then the n characters from the
temporary array are copied into the object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memmove function returns the value of s1.
<a name="7.21.2.3" href="#7.21.2.3"><h5>7.21.2.3 The strcpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strcpy(char * restrict s1,
const char * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcpy function copies the string pointed to by s2 (including the terminating null
character) into the array pointed to by s1. If copying takes place between objects that
overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcpy function returns the value of s1.
<a name="7.21.2.4" href="#7.21.2.4"><h5>7.21.2.4 The strncpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strncpy(char * restrict s1,
const char * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strncpy function copies not more than n characters (characters that follow a null
character are not copied) from the array pointed to by s2 to the array pointed to by
-<!--page 339 indent 4-->
+<!--page 339 -->
s1.<sup><a href="#note269"><b>269)</b></a></sup> If copying takes place between objects that overlap, the behavior is undefined.
-<p><!--para 3-->
+<p><!--para 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.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The strncpy function returns the value of s1.
<h6>footnotes</h6>
<a name="7.21.3.1" href="#7.21.3.1"><h5>7.21.3.1 The strcat function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strcat(char * restrict s1,
const char * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcat function appends a copy of the string pointed to by s2 (including the
terminating null character) to the end of the string pointed to by s1. The initial character
of s2 overwrites the null character at the end of s1. If copying takes place between
objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcat function returns the value of s1.
<a name="7.21.3.2" href="#7.21.3.2"><h5>7.21.3.2 The strncat function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strncat(char * restrict s1,
const char * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strncat function appends not more than n characters (a null character and
characters that follow it are not appended) from the array pointed to by s2 to the end of
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.<sup><a href="#note270"><b>270)</b></a></sup> If copying
-<!--page 340 indent 4-->
+<!--page 340 -->
takes place between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strncat function returns the value of s1.
<p><b> Forward references</b>: the strlen function (<a href="#7.21.6.3">7.21.6.3</a>).
</small>
<a name="7.21.4" href="#7.21.4"><h4>7.21.4 Comparison functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The sign of a nonzero value returned by the comparison functions memcmp, strcmp,
and strncmp is determined by the sign of the difference between the values of the first
pair of characters (both interpreted as unsigned char) that differ in the objects being
<a name="7.21.4.1" href="#7.21.4.1"><h5>7.21.4.1 The memcmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
int memcmp(const void *s1, const void *s2, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memcmp function compares the first n characters of the object pointed to by s1 to
the first n characters of the object pointed to by s2.<sup><a href="#note271"><b>271)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
pointed to by s2.
<a name="7.21.4.2" href="#7.21.4.2"><h5>7.21.4.2 The strcmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
int strcmp(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcmp function compares the string pointed to by s1 to the string pointed to by
s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
-<!--page 341 indent 4-->
+<!--page 341 -->
pointed to by s2.
<a name="7.21.4.3" href="#7.21.4.3"><h5>7.21.4.3 The strcoll function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
int strcoll(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcoll function compares the string pointed to by s1 to the string pointed to by
s2, both interpreted as appropriate to the LC_COLLATE category of the current locale.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcoll function returns an integer greater than, equal to, or less than zero,
accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
pointed to by s2 when both are interpreted as appropriate to the current locale.
<a name="7.21.4.4" href="#7.21.4.4"><h5>7.21.4.4 The strncmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
int strncmp(const char *s1, const char *s2, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strncmp function compares not more than n characters (characters that follow a
null character are not compared) from the array pointed to by s1 to the array pointed to
by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
<a name="7.21.4.5" href="#7.21.4.5"><h5>7.21.4.5 The strxfrm function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
size_t strxfrm(char * restrict s1,
const char * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strxfrm function transforms the string pointed to by s2 and places the resulting
string into the array pointed to by s1. The transformation is such that if the strcmp
function is applied to two transformed strings, it returns a value greater than, equal to, or
-<!--page 342 indent 4-->
+<!--page 342 -->
less than zero, corresponding to the result of the strcoll function applied to the same
two original strings. No more than n characters are placed into the resulting array
pointed to by s1, including the terminating null character. If n is zero, s1 is permitted to
be a null pointer. If copying takes place between objects that overlap, the behavior is
undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strxfrm function returns the length of the transformed string (not including the
terminating null character). If the value returned is n or more, the contents of the array
pointed to by s1 are indeterminate.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The value of the following expression is the size of the array needed to hold the
transformation of the string pointed to by s.
<pre>
<a name="7.21.5.1" href="#7.21.5.1"><h5>7.21.5.1 The memchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
void *memchr(const void *s, int c, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memchr function locates the first occurrence of c (converted to an unsigned
char) in the initial n characters (each interpreted as unsigned char) of the object
pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the object.
<a name="7.21.5.2" href="#7.21.5.2"><h5>7.21.5.2 The strchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strchr(const char *s, int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strchr function locates the first occurrence of c (converted to a char) in the
string pointed to by s. The terminating null character is considered to be part of the
string.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the string.
-<!--page 343 indent 4-->
+<!--page 343 -->
<a name="7.21.5.3" href="#7.21.5.3"><h5>7.21.5.3 The strcspn function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
size_t strcspn(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcspn function computes the length of the maximum initial segment of the string
pointed to by s1 which consists entirely of characters not from the string pointed to by
s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcspn function returns the length of the segment.
<a name="7.21.5.4" href="#7.21.5.4"><h5>7.21.5.4 The strpbrk function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strpbrk(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strpbrk function locates the first occurrence in the string pointed to by s1 of any
character from the string pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strpbrk function returns a pointer to the character, or a null pointer if no character
from s2 occurs in s1.
<a name="7.21.5.5" href="#7.21.5.5"><h5>7.21.5.5 The strrchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strrchr(const char *s, int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strrchr function locates the last occurrence of c (converted to a char) in the
string pointed to by s. The terminating null character is considered to be part of the
string.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strrchr function returns a pointer to the character, or a null pointer if c does not
occur in the string.
-<!--page 344 indent 4-->
+<!--page 344 -->
<a name="7.21.5.6" href="#7.21.5.6"><h5>7.21.5.6 The strspn function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
size_t strspn(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strspn function computes the length of the maximum initial segment of the string
pointed to by s1 which consists entirely of characters from the string pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strspn function returns the length of the segment.
<a name="7.21.5.7" href="#7.21.5.7"><h5>7.21.5.7 The strstr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strstr(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strstr function locates the first occurrence in the string pointed to by s1 of the
sequence of characters (excluding the terminating null character) in the string pointed to
by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strstr function returns a pointer to the located string, or a null pointer if the string
is not found. If s2 points to a string with zero length, the function returns s1.
<a name="7.21.5.8" href="#7.21.5.8"><h5>7.21.5.8 The strtok function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strtok(char * restrict s1,
const char * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A sequence of calls to the strtok function breaks the string pointed to by s1 into a
sequence of tokens, each of which is delimited by a character from the string pointed to
by s2. The first call in the sequence has a non-null first argument; subsequent calls in the
sequence have a null first argument. The separator string pointed to by s2 may be
different from call to call.
-<p><!--para 3-->
+<p><!--para 3 -->
The first call in the sequence searches the string pointed to by s1 for the first character
that is not contained in the current separator string pointed to by s2. If no such character
is found, then there are no tokens in the string pointed to by s1 and the strtok function
-<!--page 345 indent 4-->
+<!--page 345 -->
returns a null pointer. If such a character is found, it is the start of the first token.
-<p><!--para 4-->
+<p><!--para 4 -->
The strtok function then searches from there for a character that is contained in the
current separator string. If no such character is found, the current token extends to the
end of the string pointed to by s1, and subsequent searches for a token will return a null
pointer. If such a character is found, it is overwritten by a null character, which
terminates the current token. The strtok function saves a pointer to the following
character, from which the next search for a token will start.
-<p><!--para 5-->
+<p><!--para 5 -->
Each subsequent call, with a null pointer as the value of the first argument, starts
searching from the saved pointer and behaves as described above.
-<p><!--para 6-->
+<p><!--para 6 -->
The implementation shall behave as if no library function calls the strtok function.
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The strtok function returns a pointer to the first character of a token, or a null pointer
if there is no token.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE
<pre>
#include <a href="#7.21"><string.h></a>
<a name="7.21.6.1" href="#7.21.6.1"><h5>7.21.6.1 The memset function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
void *memset(void *s, int c, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memset function copies the value of c (converted to an unsigned char) into
each of the first n characters of the object pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memset function returns the value of s.
-<!--page 346 indent 4-->
+<!--page 346 -->
<a name="7.21.6.2" href="#7.21.6.2"><h5>7.21.6.2 The strerror function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
char *strerror(int errnum);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strerror function maps the number in errnum to a message string. Typically,
the values for errnum come from errno, but strerror shall map any value of type
int to a message.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the strerror function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The strerror function returns a pointer to the string, the contents of which are locale-
specific. The array pointed to shall not be modified by the program, but may be
overwritten by a subsequent call to the strerror function.
<a name="7.21.6.3" href="#7.21.6.3"><h5>7.21.6.3 The strlen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><string.h></a>
size_t strlen(const char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strlen function computes the length of the string pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strlen function returns the number of characters that precede the terminating null
character.
-<!--page 347 indent 4-->
+<!--page 347 -->
<a name="7.22" href="#7.22"><h3>7.22 Type-generic math <tgmath.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.22"><tgmath.h></a> includes the headers <a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> and
defines several type-generic macros.
-<p><!--para 2-->
+<p><!--para 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
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.<sup><a href="#note273"><b>273)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
Use of the macro invokes a function whose generic parameters have the corresponding
real type determined as follows:
<ul>
type, the type determined is double.
<li> Otherwise, the type determined is float.
</ul>
-<p><!--para 4-->
+<p><!--para 4 -->
For each unsuffixed function in <a href="#7.12"><math.h></a> for which there is a function in
<a href="#7.3"><complex.h></a> with the same name except for a c prefix, the corresponding type-
generic macro (for both functions) has the same name as the function in <a href="#7.12"><math.h></a>. The
-<!--page 348 indent 4-->
+<!--page 348 -->
<pre>
<a href="#7.12"><math.h></a> <a href="#7.3"><complex.h></a> type-generic
function function macro
fabs cabs fabs</pre>
If at least one argument for a generic parameter is complex, then use of the macro invokes
a complex function; otherwise, use of the macro invokes a real function.
-<p><!--para 5-->
+<p><!--para 5 -->
For each unsuffixed function in <a href="#7.12"><math.h></a> without a c-prefixed counterpart in
<a href="#7.3"><complex.h></a> (except modf), the corresponding type-generic macro has the same
name as the function. These type-generic macros are:
floor llrint nexttoward</pre>
If all arguments for generic parameters are real, then use of the macro invokes a real
function; otherwise, use of the macro results in undefined behavior.
-<p><!--para 6-->
+<p><!--para 6 -->
For each unsuffixed function in <a href="#7.3"><complex.h></a> that is not a c-prefixed counterpart to a
function in <a href="#7.12"><math.h></a>, the corresponding type-generic macro has the same name as the
function. These type-generic macros are:
-<!--page 349 indent 4-->
+<!--page 349 -->
<pre>
carg conj creal
cimag cproj</pre>
Use of the macro with any real or complex argument invokes a complex function.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE With the declarations
<pre>
#include <a href="#7.22"><tgmath.h></a>
double complex dc;
long double complex ldc;</pre>
functions invoked by use of type-generic macros are shown in the following table:
-<!--page 350 indent 4-->
+<!--page 350 -->
<pre>
macro use invokes
exp(n) exp(n), the function
<a name="7.23" href="#7.23"><h3>7.23 Date and time <time.h></h3></a>
<a name="7.23.1" href="#7.23.1"><h4>7.23.1 Components of time</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.23"><time.h></a> defines two macros, and declares several types and functions for
manipulating time. Many functions deal with a calendar time that represents the current
date (according to the Gregorian calendar) and time. Some functions deal with local
time, which is the calendar time expressed for some specific time zone, and with Daylight
Saving Time, which is a temporary change in the algorithm for determining local time.
The local time zone and Daylight Saving Time are implementation-defined.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>); and
<pre>
CLOCKS_PER_SEC</pre>
which expands to an expression with type clock_t (described below) that is the
number per second of the value returned by the clock function.
-<p><!--para 3-->
+<p><!--para 3 -->
The types declared are size_t (described in <a href="#7.17">7.17</a>);
<pre>
clock_t</pre>
<pre>
struct tm</pre>
which holds the components of a calendar time, called the broken-down time.
-<p><!--para 4-->
+<p><!--para 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
-<!--page 351 indent 4-->
+<!--page 351 -->
The value of tm_isdst is positive if Daylight Saving Time is in effect, zero if Daylight
Saving Time is not in effect, and negative if the information is not available.
<a name="7.23.2.1" href="#7.23.2.1"><h5>7.23.2.1 The clock function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
clock_t clock(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The clock function determines the processor time used.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The clock function returns the implementation's best approximation to the processor
time used by the program since the beginning of an implementation-defined era related
only to the program invocation. To determine the time in seconds, the value returned by
<a name="7.23.2.2" href="#7.23.2.2"><h5>7.23.2.2 The difftime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
double difftime(time_t time1, time_t time0);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The difftime function computes the difference between two calendar times: time1 -
time0.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The difftime function returns the difference expressed in seconds as a double.
-<!--page 352 indent 4-->
+<!--page 352 -->
<a name="7.23.2.3" href="#7.23.2.3"><h5>7.23.2.3 The mktime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
time_t mktime(struct tm *timeptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mktime function converts the broken-down time, expressed as local time, in the
structure pointed to by timeptr into a calendar time value with the same encoding as
that of the values returned by the time function. The original values of the tm_wday
time, but with their values forced to the ranges indicated above; the final value of
tm_mday is not set until tm_mon and tm_year are determined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mktime function returns the specified calendar time encoded as a value of type
time_t. If the calendar time cannot be represented, the function returns the value
(time_t)(-1).
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE What day of the week is July 4, 2001?
<pre>
#include <a href="#7.19"><stdio.h></a>
-<!--page 353 indent 4-->
+<!--page 353 -->
<pre>
time_str.tm_year = 2001 - 1900;
time_str.tm_mon = 7 - 1;
<a name="7.23.2.4" href="#7.23.2.4"><h5>7.23.2.4 The time function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
time_t time(time_t *timer);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The time function determines the current calendar time. The encoding of the value is
unspecified.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The time function returns the implementation's best approximation to the current
calendar time. The value (time_t)(-1) is returned if the calendar time is not
available. If timer is not a null pointer, the return value is also assigned to the object it
points to.
<a name="7.23.3" href="#7.23.3"><h4>7.23.3 Time conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Except for the strftime function, these functions each return a pointer to one of two
types of static objects: a broken-down time structure or an array of char. Execution of
any of the functions that return a pointer to one of these object types may overwrite the
<a name="7.23.3.1" href="#7.23.3.1"><h5>7.23.3.1 The asctime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
char *asctime(const struct tm *timeptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The asctime function converts the broken-down time in the structure pointed to by
timeptr into a string in the form
-<!--page 354 indent 4-->
+<!--page 354 -->
<pre>
Sun Sep 16 01:03:52 1973\n\0</pre>
using the equivalent of the following algorithm.
return result;</pre>
}
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The asctime function returns a pointer to the string.
<a name="7.23.3.2" href="#7.23.3.2"><h5>7.23.3.2 The ctime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
char *ctime(const time_t *timer);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ctime function converts the calendar time pointed to by timer to local time in the
form of a string. It is equivalent to
<pre>
asctime(localtime(timer))</pre>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ctime function returns the pointer returned by the asctime function with that
broken-down time as argument.
<p><b> Forward references</b>: the localtime function (<a href="#7.23.3.4">7.23.3.4</a>).
-<!--page 355 indent 4-->
+<!--page 355 -->
<a name="7.23.3.3" href="#7.23.3.3"><h5>7.23.3.3 The gmtime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
struct tm *gmtime(const time_t *timer);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The gmtime function converts the calendar time pointed to by timer into a broken-
down time, expressed as UTC.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The gmtime function returns a pointer to the broken-down time, or a null pointer if the
specified time cannot be converted to UTC.
<a name="7.23.3.4" href="#7.23.3.4"><h5>7.23.3.4 The localtime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
struct tm *localtime(const time_t *timer);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The localtime function converts the calendar time pointed to by timer into a
broken-down time, expressed as local time.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The localtime function returns a pointer to the broken-down time, or a null pointer if
the specified time cannot be converted to local time.
<a name="7.23.3.5" href="#7.23.3.5"><h5>7.23.3.5 The strftime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
size_t strftime(char * restrict s,
const char * restrict format,
const struct tm * restrict timeptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strftime function places characters into the array pointed to by s as controlled by
the string pointed to by format. The format shall be a multibyte character sequence,
beginning and ending in its initial shift state. The format string consists of zero or
consists of a % character, possibly followed by an E or O modifier character (described
below), followed by a character that determines the behavior of the conversion specifier.
All ordinary multibyte characters (including the terminating null character) are copied
-<!--page 356 indent 4-->
+<!--page 356 -->
unchanged into the array. If copying takes place between objects that overlap, the
behavior is undefined. No more than maxsize characters are placed into the array.
-<p><!--para 3-->
+<p><!--para 3 -->
Each conversion specifier is replaced by appropriate characters as described in the
following list. The appropriate characters are determined using the LC_TIME category
of the current locale and by the values of zero or more members of the broken-down time
%S is replaced by the second as a decimal number (00-60). [tm_sec]
%t is replaced by a horizontal-tab character.
%T is equivalent to ''%H:%M:%S'' (the ISO 8601 time format). [tm_hour, tm_min,
-<!--page 357 indent 4-->
+<!--page 357 -->
<pre>
tm_sec]</pre>
%u is replaced by the ISO 8601 weekday as a decimal number (1-7), where Monday
<pre>
time zone is determinable. [tm_isdst]</pre>
%% is replaced by %.
-<p><!--para 4-->
+<p><!--para 4 -->
Some conversion specifiers can be modified by the inclusion of an E or O modifier
character to indicate an alternative format or specification. If the alternative format or
specification does not exist for the current locale, the modifier is ignored.
<pre>
(filled as needed with leading spaces).</pre>
%OH is replaced by the hour (24-hour clock), using the locale's alternative numeric
-<!--page 358 indent 4-->
+<!--page 358 -->
<pre>
symbols.</pre>
%OI is replaced by the hour (12-hour clock), using the locale's alternative numeric
<pre>
symbols.</pre>
%Oy is replaced by the last 2 digits of the year, using the locale's alternative numeric
-<p><!--para 5-->
+<p><!--para 5 -->
<pre>
symbols.</pre>
%g, %G, and %V give values according to the ISO 8601 week-based year. In this system,
December 29th, 30th, or 31st is a Monday, it and any following days are part of week 1 of
the following year. Thus, for Tuesday 30th December 1997, %G is replaced by 1998 and
%V is replaced by 01.
-<p><!--para 6-->
+<p><!--para 6 -->
If a conversion specifier is not one of the above, the behavior is undefined.
-<p><!--para 7-->
+<p><!--para 7 -->
In the "C" locale, the E and O modifiers are ignored and the replacement strings for the
following specifiers are:
%a the first three characters of %A.
%x equivalent to ''%m/%d/%y''.
%X equivalent to %T.
%Z implementation-defined.
-<!--page 359 indent 4-->
+<!--page 359 -->
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
If the total number of resulting characters including the terminating null character is not
more than maxsize, the strftime function returns the number of characters placed
into the array pointed to by s not including the terminating null character. Otherwise,
zero is returned and the contents of the array are indeterminate.
-<!--page 360 indent 4-->
+<!--page 360 -->
<a name="7.24" href="#7.24"><h3>7.24 Extended multibyte and wide character utilities <wchar.h></h3></a>
<a name="7.24.1" href="#7.24.1"><h4>7.24.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.24"><wchar.h></a> declares four data types, one tag, four macros, and many
functions.<sup><a href="#note277"><b>277)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are wchar_t and size_t (both described in <a href="#7.17">7.17</a>);
<pre>
mbstate_t</pre>
<pre>
struct tm</pre>
which is declared as an incomplete structure type (the contents are described in <a href="#7.23.1">7.23.1</a>).
-<p><!--para 3-->
+<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.17">7.17</a>); WCHAR_MIN and WCHAR_MAX
(described in <a href="#7.18.3">7.18.3</a>); and
<pre>
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.
-<p><!--para 4-->
+<p><!--para 4 -->
The functions declared are grouped as follows:
<ul>
<li> Functions that perform input and output of wide characters, or multibyte characters,
<li> Functions that perform general wide string manipulation;
-<!--page 361 indent 4-->
+<!--page 361 -->
<li> Functions for wide string date and time conversion; and
<li> Functions that provide extended capabilities for conversion between multibyte and
wide character sequences.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
Unless explicitly stated otherwise, if the execution of a function described in this
subclause causes copying to take place between objects that overlap, the behavior is
undefined.
</small>
<a name="7.24.2" href="#7.24.2"><h4>7.24.2 Formatted wide character input/output functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The formatted wide character input/output functions shall behave as if there is a sequence
point after the actions associated with each specifier.<sup><a href="#note280"><b>280)</b></a></sup>
<a name="7.24.2.1" href="#7.24.2.1"><h5>7.24.2.1 The fwprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fwprintf(FILE * restrict stream,
const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fwprintf function writes output to the stream pointed to by stream, under
control of the wide string pointed to by format that specifies how subsequent arguments
are converted for output. If there are insufficient arguments for the format, the behavior
is undefined. If the format is exhausted while arguments remain, the excess arguments
are evaluated (as always) but are otherwise ignored. The fwprintf function returns
when the end of the format string is encountered.
-<p><!--para 3-->
+<p><!--para 3 -->
The format is composed of zero or more directives: ordinary wide characters (not %),
which are copied unchanged to the output stream; and conversion specifications, each of
which results in fetching zero or more subsequent arguments, converting them, if
applicable, according to the corresponding conversion specifier, and then writing the
result to the output stream.
-<p><!--para 4-->
+<p><!--para 4 -->
Each conversion specification is introduced by the wide character %. After the %, the
following appear in sequence:
<ul>
than the field width, it is padded with spaces (by default) on the left (or right, if the
-<!--page 362 indent 4-->
+<!--page 362 -->
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.<sup><a href="#note281"><b>281)</b></a></sup>
<li> A conversion specifier wide character that specifies the type of conversion to be
applied.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
As noted above, a field width, or precision, or both, may be indicated by an asterisk. In
this case, an int argument supplies the field width or precision. The arguments
specifying field width, or precision, or both, shall appear (in that order) before the
argument (if any) to be converted. A negative field width argument is taken as a - flag
followed by a positive field width. A negative precision argument is taken as if the
precision were omitted.
-<p><!--para 6-->
+<p><!--para 6 -->
The flag wide characters and their meanings are:
- The result of the conversion is left-justified within the field. (It is right-justified if
<pre>
zero (if the value and precision are both 0, a single 0 is printed). For x (or X)
conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g,</pre>
-<!--page 363 indent 4-->
+<!--page 363 -->
<pre>
and G conversions, the result of converting a floating-point number always
contains a decimal-point wide character, even if no digits follow it. (Normally, a
digit follows it.) For g and G conversions, trailing zeros are not removed from the
result. For other conversions, the behavior is undefined.</pre>
0 For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
-<p><!--para 7-->
+<p><!--para 7 -->
<pre>
(following any indication of sign or base) are used to pad to the field width rather
than performing space padding, except when converting an infinity or NaN. If the
following n conversion specifier applies to a pointer to a long long int
argument.</pre>
j Specifies that a following d, i, o, u, x, or X conversion specifier applies to
-<!--page 364 indent 4-->
+<!--page 364 -->
<pre>
an intmax_t or uintmax_t argument; or that a following n conversion
specifier applies to a pointer to an intmax_t argument.</pre>
applies to a long double argument.</pre>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
-<p><!--para 8-->
+<p><!--para 8 -->
The conversion specifiers and their meanings are:
d,i The int argument is converted to signed decimal in the style [-]dddd. The
<pre>
with leading zeros. The default precision is 1. The result of converting a
zero value with a precision of zero is no wide characters.</pre>
f,F A double argument representing a floating-point number is converted to
-<!--page 365 indent 0-->
+<!--page 365 -->
<pre>
decimal notation in the style [-]ddd.ddd, where the number of digits after
the decimal-point wide character is equal to the precision specification. If the
is missing and FLT_RADIX is a power of 2, then the precision is sufficient</pre>
-<!--page 366 indent 0-->
+<!--page 366 -->
<pre>
for an exact representation of the value; if the precision is missing and
FLT_RADIX is not a power of 2, then the precision is sufficient to
<pre>
converted to a sequence of printing wide characters, in an implementation-</pre>
-<!--page 367 indent 5-->
+<!--page 367 -->
<pre>
defined manner.</pre>
n The argument shall be a pointer to signed integer into which is written the
conversion specification includes any flags, a field width, or a precision, the
behavior is undefined.</pre>
% A % wide character is written. No argument is converted. The complete
-<p><!--para 9-->
+<p><!--para 9 -->
<pre>
conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note286"><b>286)</b></a></sup> If any argument is
not the correct type for the corresponding conversion specification, the behavior is
undefined.
-<p><!--para 10-->
+<p><!--para 10 -->
In no case does a nonexistent or small field width cause truncation of a field; if the result
of a conversion is wider than the field width, the field is expanded to contain the
conversion result.
-<p><!--para 11-->
+<p><!--para 11 -->
For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
to a hexadecimal floating number with the given precision.
Recommended practice
-<p><!--para 12-->
+<p><!--para 12 -->
For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
representable in the given precision, the result should be one of the two adjacent numbers
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.
-<p><!--para 13-->
+<p><!--para 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.<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
of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that
the error should have a correct sign for the current rounding direction.
<h6>Returns</h6>
-<p><!--para 14-->
+<p><!--para 14 -->
The fwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
-<!--page 368 indent 5-->
+<!--page 368 -->
Environmental limits
-<p><!--para 15-->
+<p><!--para 15 -->
The number of wide characters that can be produced by any single conversion shall be at
least 4095.
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE To print a date and time in the form ''Sunday, July 3, 10:02'' followed by pi to five decimal
places:
<pre>
<a name="7.24.2.2" href="#7.24.2.2"><h5>7.24.2.2 The fwscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fwscanf(FILE * restrict stream,
const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fwscanf function reads input from the stream pointed to by stream, under
control of the wide string pointed to by format that specifies the admissible input
sequences and how they are to be converted for assignment, using subsequent arguments
arguments for the format, the behavior is undefined. If the format is exhausted while
arguments remain, the excess arguments are evaluated (as always) but are otherwise
ignored.
-<p><!--para 3-->
+<p><!--para 3 -->
The format is composed of zero or more directives: one or more white-space wide
characters, an ordinary wide character (neither % nor a white-space wide character), or a
conversion specification. Each conversion specification is introduced by the wide
<li> An optional assignment-suppressing wide character *.
<li> An optional decimal integer greater than zero that specifies the maximum field width
(in wide characters).
-<!--page 369 indent 5-->
+<!--page 369 -->
<li> An optional length modifier that specifies the size of the receiving object.
<li> A conversion specifier wide character that specifies the type of conversion to be
applied.
</ul>
-<p><!--para 4-->
+<p><!--para 4 -->
The fwscanf function executes each directive of the format in turn. If a directive fails,
as detailed below, the function returns. Failures are described as input failures (due to the
occurrence of an encoding error or the unavailability of input characters), or matching
failures (due to inappropriate input).
-<p><!--para 5-->
+<p><!--para 5 -->
A directive composed of white-space wide character(s) is executed by reading input up to
the first non-white-space wide character (which remains unread), or until no more wide
characters can be read.
-<p><!--para 6-->
+<p><!--para 6 -->
A directive that is an ordinary wide character is executed by reading the next wide
character of the stream. If that wide character differs from the directive, the directive
fails and the differing and subsequent wide characters remain unread. Similarly, if end-
of-file, an encoding error, or a read error prevents a wide character from being read, the
directive fails.
-<p><!--para 7-->
+<p><!--para 7 -->
A directive that is a conversion specification defines a set of matching input sequences, as
described below for each specifier. A conversion specification is executed in the
following steps:
-<p><!--para 8-->
+<p><!--para 8 -->
Input white-space wide characters (as specified by the iswspace function) are skipped,
unless the specification includes a [, c, or n specifier.<sup><a href="#note288"><b>288)</b></a></sup>
-<p><!--para 9-->
+<p><!--para 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
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.
-<p><!--para 10-->
+<p><!--para 10 -->
Except in the case of a % specifier, the input item (or, in the case of a %n directive, the
count of input wide characters) is converted to a type appropriate to the conversion
specifier. If the input item is not a matching sequence, the execution of the directive fails:
following the format argument that has not already received a conversion result. If this
-<!--page 370 indent 5-->
+<!--page 370 -->
object does not have an appropriate type, or if the result of the conversion cannot be
represented in the object, the behavior is undefined.
-<p><!--para 11-->
+<p><!--para 11 -->
The length modifiers and their meanings are:
hh Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
<pre>
applies to an argument with type pointer to long double.</pre>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
-<p><!--para 12-->
+<p><!--para 12 -->
The conversion specifiers and their meanings are:
d Matches an optionally signed decimal integer, whose format is the same as
<pre>
for the base argument. The corresponding argument shall be a pointer to
signed integer.</pre>
i Matches an optionally signed integer, whose format is the same as expected
-<!--page 371 indent 0-->
+<!--page 371 -->
<pre>
for the subject sequence of the wcstol function with the value 0 for the
base argument. The corresponding argument shall be a pointer to signed
pointer to the initial element of an array of wchar_t large enough to accept
the sequence. No null wide character is added.</pre>
s Matches a sequence of non-white-space wide characters.
-<!--page 372 indent 0-->
+<!--page 372 -->
<pre>
If no l length modifier is present, characters from the input field are
converted as if by repeated calls to the wcrtomb function, with the
during the same program execution, the pointer that results shall compare
equal to that value; otherwise the behavior of the %p conversion is undefined.</pre>
n No input is consumed. The corresponding argument shall be a pointer to
-<!--page 373 indent 5-->
+<!--page 373 -->
<pre>
signed integer into which is to be written the number of wide characters read
from the input stream so far by this call to the fwscanf function. Execution
assignment-suppressing wide character or a field width, the behavior is
undefined.</pre>
% Matches a single % wide character; no conversion or assignment occurs. The
-<p><!--para 13-->
+<p><!--para 13 -->
<pre>
complete conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note290"><b>290)</b></a></sup>
-<p><!--para 14-->
+<p><!--para 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.
-<p><!--para 15-->
+<p><!--para 15 -->
Trailing white space (including new-line wide characters) is left unread unless matched
by a directive. The success of literal matches and suppressed assignments is not directly
determinable other than via the %n directive.
<h6>Returns</h6>
-<p><!--para 16-->
+<p><!--para 16 -->
The fwscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the function returns the number of input items
assigned, which can be fewer than provided for, or even zero, in the event of an early
matching failure.
-<p><!--para 17-->
+<p><!--para 17 -->
EXAMPLE 1 The call:
<pre>
#include <a href="#7.19"><stdio.h></a>
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
-<p><!--para 18-->
+<p><!--para 18 -->
EXAMPLE 2 The call:
<pre>
#include <a href="#7.19"><stdio.h></a>
56.0. The next wide character read from the input stream will be a.
-<!--page 374 indent 4-->
+<!--page 374 -->
<p><b> Forward references</b>: the wcstod, wcstof, and wcstold functions (<a href="#7.24.4.1.1">7.24.4.1.1</a>), the
wcstol, wcstoll, wcstoul, and wcstoull functions (<a href="#7.24.4.1.2">7.24.4.1.2</a>), the wcrtomb
function (<a href="#7.24.6.3.3">7.24.6.3.3</a>).
<a name="7.24.2.3" href="#7.24.2.3"><h5>7.24.2.3 The swprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int swprintf(wchar_t * restrict s,
size_t n,
const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The swprintf function is equivalent to fwprintf, except that the argument s
specifies an array of wide characters into which the generated output is to be written,
rather than written to a stream. No more than n wide characters are written, including a
terminating null wide character, which is always added (unless n is zero).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The swprintf function returns the number of wide characters written in the array, not
counting the terminating null wide character, or a negative value if an encoding error
occurred or if n or more wide characters were requested to be written.
<a name="7.24.2.4" href="#7.24.2.4"><h5>7.24.2.4 The swscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int swscanf(const wchar_t * restrict s,
const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The swscanf function is equivalent to fwscanf, except that the argument s specifies a
wide string from which the input is to be obtained, rather than from a stream. Reaching
the end of the wide string is equivalent to encountering end-of-file for the fwscanf
function.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The swscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the swscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
early matching failure.
-<!--page 375 indent 4-->
+<!--page 375 -->
<a name="7.24.2.5" href="#7.24.2.5"><h5>7.24.2.5 The vfwprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vfwprintf function is equivalent to fwprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwprintf function does not invoke the
va_end macro.<sup><a href="#note291"><b>291)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vfwprintf function returns the number of wide characters transmitted, or a
negative value if an output or encoding error occurred.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The following shows the use of the vfwprintf function in a general error-reporting
routine.
<pre>
-<!--page 376 indent 4-->
+<!--page 376 -->
<h6>footnotes</h6>
<p><small><a name="note291" href="#note291">291)</a> As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf
<a name="7.24.2.6" href="#7.24.2.6"><h5>7.24.2.6 The vfwscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.19"><stdio.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vfwscanf function is equivalent to fwscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwscanf function does not invoke the
va_end macro.291)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vfwscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vfwscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
<a name="7.24.2.7" href="#7.24.2.7"><h5>7.24.2.7 The vswprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vswprintf function is equivalent to swprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswprintf function does not invoke the
va_end macro.291)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vswprintf function returns the number of wide characters written in the array, not
counting the terminating null wide character, or a negative value if an encoding error
occurred or if n or more wide characters were requested to be generated.
-<!--page 377 indent 4-->
+<!--page 377 -->
<a name="7.24.2.8" href="#7.24.2.8"><h5>7.24.2.8 The vswscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vswscanf function is equivalent to swscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswscanf function does not invoke the
va_end macro.291)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vswscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vswscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
<a name="7.24.2.9" href="#7.24.2.9"><h5>7.24.2.9 The vwprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vwprintf(const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vwprintf function is equivalent to wprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwprintf function does not invoke the
va_end macro.291)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
-<!--page 378 indent 4-->
+<!--page 378 -->
<a name="7.24.2.10" href="#7.24.2.10"><h5>7.24.2.10 The vwscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.15"><stdarg.h></a>
#include <a href="#7.24"><wchar.h></a>
int vwscanf(const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vwscanf function is equivalent to wscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwscanf function does not invoke the
va_end macro.291)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vwscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the vwscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
<a name="7.24.2.11" href="#7.24.2.11"><h5>7.24.2.11 The wprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wprintf(const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wprintf function is equivalent to fwprintf with the argument stdout
interposed before the arguments to wprintf.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
<a name="7.24.2.12" href="#7.24.2.12"><h5>7.24.2.12 The wscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wscanf(const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wscanf function is equivalent to fwscanf with the argument stdin interposed
before the arguments to wscanf.
-<!--page 379 indent 4-->
+<!--page 379 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wscanf function returns the value of the macro EOF if an input failure occurs
before any conversion. Otherwise, the wscanf function returns the number of input
items assigned, which can be fewer than provided for, or even zero, in the event of an
<a name="7.24.3.1" href="#7.24.3.1"><h5>7.24.3.1 The fgetwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wint_t fgetwc(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next wide character is present, the fgetwc function obtains that wide character as a
wchar_t converted to a wint_t and advances the associated file position indicator for
the stream (if defined).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetwc function returns WEOF. Otherwise,
the fgetwc function returns the next wide character from the input stream pointed to by
<a name="7.24.3.2" href="#7.24.3.2"><h5>7.24.3.2 The fgetws function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wchar_t *fgetws(wchar_t * restrict s,
int n, FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fgetws function reads at most one less than the number of wide characters
specified by n from the stream pointed to by stream into the array pointed to by s. No
-<!--page 380 indent 4-->
+<!--page 380 -->
additional wide characters are read after a new-line wide character (which is retained) or
after end-of-file. A null wide character is written immediately after the last wide
character read into the array.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fgetws function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
null pointer is returned. If a read or encoding error occurs during the operation, the array
<a name="7.24.3.3" href="#7.24.3.3"><h5>7.24.3.3 The fputwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wint_t fputwc(wchar_t c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fputwc function writes the wide character specified by c to the output stream
pointed to by stream, at the position indicated by the associated file position indicator
for the stream (if defined), and advances the indicator appropriately. If the file cannot
support positioning requests, or if the stream was opened with append mode, the
character is appended to the output stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fputwc function returns the wide character written. If a write error occurs, the
error indicator for the stream is set and fputwc returns WEOF. If an encoding error
occurs, the value of the macro EILSEQ is stored in errno and fputwc returns WEOF.
<a name="7.24.3.4" href="#7.24.3.4"><h5>7.24.3.4 The fputws function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fputws(const wchar_t * restrict s,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fputws function writes the wide string pointed to by s to the stream pointed to by
stream. The terminating null wide character is not written.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fputws function returns EOF if a write or encoding error occurs; otherwise, it
returns a nonnegative value.
-<!--page 381 indent 4-->
+<!--page 381 -->
<a name="7.24.3.5" href="#7.24.3.5"><h5>7.24.3.5 The fwide function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int fwide(FILE *stream, int mode);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fwide function determines the orientation of the stream pointed to by stream. If
mode is greater than zero, the function first attempts to make the stream wide oriented. If
mode is less than zero, the function first attempts to make the stream byte oriented.<sup><a href="#note293"><b>293)</b></a></sup>
Otherwise, mode is zero and the function does not alter the orientation of the stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fwide function returns a value greater than zero if, after the call, the stream has
wide orientation, a value less than zero if the stream has byte orientation, or zero if the
stream has no orientation.
<a name="7.24.3.6" href="#7.24.3.6"><h5>7.24.3.6 The getwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wint_t getwc(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getwc function is equivalent to fgetwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so the argument should never be an
expression with side effects.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The getwc function returns the next wide character from the input stream pointed to by
stream, or WEOF.
<a name="7.24.3.7" href="#7.24.3.7"><h5>7.24.3.7 The getwchar function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wint_t getwchar(void);</pre>
-<!--page 382 indent 4-->
+<!--page 382 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getwchar function is equivalent to getwc with the argument stdin.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The getwchar function returns the next wide character from the input stream pointed to
by stdin, or WEOF.
<a name="7.24.3.8" href="#7.24.3.8"><h5>7.24.3.8 The putwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wint_t putwc(wchar_t c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The putwc function is equivalent to fputwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so that argument should never be an
expression with side effects.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The putwc function returns the wide character written, or WEOF.
<a name="7.24.3.9" href="#7.24.3.9"><h5>7.24.3.9 The putwchar function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wint_t putwchar(wchar_t c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The putwchar function is equivalent to putwc with the second argument stdout.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The putwchar function returns the character written, or WEOF.
<a name="7.24.3.10" href="#7.24.3.10"><h5>7.24.3.10 The ungetwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wint_t ungetwc(wint_t c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ungetwc function pushes the wide character specified by c back onto the input
stream pointed to by stream. Pushed-back wide characters will be returned by
subsequent reads on that stream in the reverse order of their pushing. A successful
-<!--page 383 indent 4-->
+<!--page 383 -->
intervening call (with the stream pointed to by stream) to a file positioning function
(fseek, fsetpos, or rewind) discards any pushed-back wide characters for the
stream. The external storage corresponding to the stream is unchanged.
-<p><!--para 3-->
+<p><!--para 3 -->
One wide character of pushback is guaranteed, even if the call to the ungetwc function
follows just after a call to a formatted wide character input function fwscanf,
vfwscanf, vwscanf, or wscanf. If the ungetwc function is called too many times
on the same stream without an intervening read or file positioning operation on that
stream, the operation may fail.
-<p><!--para 4-->
+<p><!--para 4 -->
If the value of c equals that of the macro WEOF, the operation fails and the input stream is
unchanged.
-<p><!--para 5-->
+<p><!--para 5 -->
A successful call to the ungetwc function clears the end-of-file indicator for the stream.
The value of the file position indicator for the stream after reading or discarding all
pushed-back wide characters is the same as it was before the wide characters were pushed
call to the ungetwc function is unspecified until all pushed-back wide characters are
read or discarded.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The ungetwc function returns the wide character pushed back, or WEOF if the operation
fails.
<a name="7.24.4" href="#7.24.4"><h4>7.24.4 General wide string utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.24"><wchar.h></a> declares a number of functions useful for wide string
manipulation. Various methods are used for determining the lengths of the arrays, but in
all cases a wchar_t * argument points to the initial (lowest addressed) element of the
array. If an array is accessed beyond the end of an object, the behavior is undefined.
-<p><!--para 2-->
+<p><!--para 2 -->
Where an argument declared as size_t n determines the length of the array for a
function, n can have the value zero on a call to that function. Unless explicitly stated
otherwise in the description of a particular function in this subclause, pointer arguments
function that locates a wide character finds no occurrence, a function that compares two
wide character sequences returns zero, and a function that copies wide characters copies
zero wide characters.
-<!--page 384 indent 4-->
+<!--page 384 -->
<a name="7.24.4.1" href="#7.24.4.1"><h5>7.24.4.1 Wide string numeric conversion functions</h5></a>
<a name="7.24.4.1.1" href="#7.24.4.1.1"><h5>7.24.4.1.1 The wcstod, wcstof, and wcstold functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
double wcstod(const wchar_t * restrict nptr,
long double wcstold(const wchar_t * restrict nptr,
wchar_t ** restrict endptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcstod, wcstof, and wcstold functions convert the initial portion of the wide
string pointed to by nptr to double, float, and long double representation,
respectively. First, they decompose the input string into three parts: an initial, possibly
infinity or NaN; and a final wide string of one or more unrecognized wide characters,
including the terminating null wide character of the input wide string. Then, they attempt
to convert the subject sequence to a floating-point number, and return the result.
-<p><!--para 3-->
+<p><!--para 3 -->
The expected form of the subject sequence is an optional plus or minus sign, then one of
the following:
<ul>
</ul>
The subject sequence is defined as the longest initial subsequence of the input wide
string, starting with the first non-white-space wide character, that is of the expected form.
-<!--page 385 indent 4-->
+<!--page 385 -->
The subject sequence contains no wide characters if the input wide string is not of the
expected form.
-<p><!--para 4-->
+<p><!--para 4 -->
If the subject sequence has the expected form for a floating-point number, the sequence of
wide characters starting with the first digit or the decimal-point wide character
(whichever occurs first) is interpreted as a floating constant according to the rules of
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.
-<p><!--para 5-->
+<p><!--para 5 -->
If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the
value resulting from the conversion is correctly rounded.
-<p><!--para 6-->
+<p><!--para 6 -->
In other than the "C" locale, additional locale-specific subject sequence forms may be
accepted.
-<p><!--para 7-->
+<p><!--para 7 -->
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
Recommended practice
-<p><!--para 8-->
+<p><!--para 8 -->
If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
the result is not exactly representable, the result should be one of the two numbers in the
appropriate internal format that are adjacent to the hexadecimal floating source value,
-<!--page 386 indent 5-->
-<p><!--para 9-->
+<!--page 386 -->
+<p><!--para 9 -->
If the subject sequence has the decimal form and at most DECIMAL_DIG (defined in
<a href="#7.7"><float.h></a>) significant digits, the result should be correctly rounded. If the subject
sequence D has the decimal form and more than DECIMAL_DIG significant digits,
stipulation that the error with respect to D should have a correct sign for the current
rounding direction.<sup><a href="#note296"><b>296)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
The functions return the converted value, if any. If no conversion could be performed,
zero is returned. If the correct value is outside the range of representable values, plus or
minus HUGE_VAL, HUGE_VALF, or HUGE_VALL is returned (according to the return
-<!--page 387 indent 4-->
+<!--page 387 -->
<h6>footnotes</h6>
<p><small><a name="note294" href="#note294">294)</a> It is unspecified whether a minus-signed sequence is converted to a negative number directly or by
<a name="7.24.4.1.2" href="#7.24.4.1.2"><h5>7.24.4.1.2 The wcstol, wcstoll, wcstoul, and wcstoull functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
long int wcstol(
wchar_t ** restrict endptr,
int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcstol, wcstoll, wcstoul, and wcstoull functions convert the initial
portion of the wide string pointed to by nptr to long int, long long int,
unsigned long int, and unsigned long long int representation,
by the value of base, and a final wide string of one or more unrecognized wide
characters, including the terminating null wide character of the input wide string. Then,
they attempt to convert the subject sequence to an integer, and return the result.
-<p><!--para 3-->
+<p><!--para 3 -->
If the value of base is zero, the expected form of the subject sequence is that of an
integer constant as described for the corresponding single-byte characters in <a href="#6.4.4.1">6.4.4.1</a>,
optionally preceded by a plus or minus sign, but not including an integer suffix. If the
letters and digits whose ascribed values are less than that of base are permitted. If the
value of base is 16, the wide characters 0x or 0X may optionally precede the sequence
of letters and digits, following the sign if present.
-<!--page 388 indent 4-->
-<p><!--para 4-->
+<!--page 388 -->
+<p><!--para 4 -->
The subject sequence is defined as the longest initial subsequence of the input wide
string, starting with the first non-white-space wide character, that is of the expected form.
The subject sequence contains no wide characters if the input wide string is empty or
consists entirely of white space, or if the first non-white-space wide character is other
than a sign or a permissible letter or digit.
-<p><!--para 5-->
+<p><!--para 5 -->
If the subject sequence has the expected form and the value of base is zero, the sequence
of wide characters starting with the first digit is interpreted as an integer constant
according to the rules of <a href="#6.4.4.1">6.4.4.1</a>. If the subject sequence has the expected form and the
resulting from the conversion is negated (in the return type). A pointer to the final wide
string is stored in the object pointed to by endptr, provided that endptr is not a null
pointer.
-<p><!--para 6-->
+<p><!--para 6 -->
In other than the "C" locale, additional locale-specific subject sequence forms may be
accepted.
-<p><!--para 7-->
+<p><!--para 7 -->
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The wcstol, wcstoll, wcstoul, and wcstoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
is outside the range of representable values, LONG_MIN, LONG_MAX, LLONG_MIN,
<a name="7.24.4.2.1" href="#7.24.4.2.1"><h5>7.24.4.2.1 The wcscpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcscpy(wchar_t * restrict s1,
const wchar_t * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscpy function copies the wide string pointed to by s2 (including the terminating
null wide character) into the array pointed to by s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscpy function returns the value of s1.
-<!--page 389 indent 4-->
+<!--page 389 -->
<a name="7.24.4.2.2" href="#7.24.4.2.2"><h5>7.24.4.2.2 The wcsncpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsncpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsncpy function copies not more than n wide characters (those that follow a null
wide character are not copied) from the array pointed to by s2 to the array pointed to by
s1.<sup><a href="#note297"><b>297)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The wcsncpy function returns the value of s1.
<h6>footnotes</h6>
<a name="7.24.4.2.3" href="#7.24.4.2.3"><h5>7.24.4.2.3 The wmemcpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemcpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemcpy function copies n wide characters from the object pointed to by s2 to the
object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemcpy function returns the value of s1.
-<!--page 390 indent 4-->
+<!--page 390 -->
<a name="7.24.4.2.4" href="#7.24.4.2.4"><h5>7.24.4.2.4 The wmemmove function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemmove function copies n wide characters from the object pointed to by s2 to
the object pointed to by s1. Copying takes place as if the n wide characters from the
object pointed to by s2 are first copied into a temporary array of n wide characters that
does not overlap the objects pointed to by s1 or s2, and then the n wide characters from
the temporary array are copied into the object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemmove function returns the value of s1.
<a name="7.24.4.3" href="#7.24.4.3"><h5>7.24.4.3 Wide string concatenation functions</h5></a>
<a name="7.24.4.3.1" href="#7.24.4.3.1"><h5>7.24.4.3.1 The wcscat function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcscat(wchar_t * restrict s1,
const wchar_t * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscat function appends a copy of the wide string pointed to by s2 (including the
terminating null wide character) to the end of the wide string pointed to by s1. The initial
wide character of s2 overwrites the null wide character at the end of s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscat function returns the value of s1.
<a name="7.24.4.3.2" href="#7.24.4.3.2"><h5>7.24.4.3.2 The wcsncat function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsncat(wchar_t * restrict s1,
const wchar_t * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsncat function appends not more than n wide characters (a null wide character
and those that follow it are not appended) from the array pointed to by s2 to the end of
-<!--page 391 indent 4-->
+<!--page 391 -->
the wide string pointed to by s1. The initial wide character of s2 overwrites the null
wide character at the end of s1. A terminating null wide character is always appended to
the result.<sup><a href="#note298"><b>298)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsncat function returns the value of s1.
<h6>footnotes</h6>
</small>
<a name="7.24.4.4" href="#7.24.4.4"><h5>7.24.4.4 Wide string comparison functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Unless explicitly stated otherwise, the functions described in this subclause order two
wide characters the same way as two integers of the underlying integer type designated
by wchar_t.
<a name="7.24.4.4.1" href="#7.24.4.4.1"><h5>7.24.4.4.1 The wcscmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wcscmp(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscmp function compares the wide string pointed to by s1 to the wide string
pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscmp function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
wide string pointed to by s2.
<a name="7.24.4.4.2" href="#7.24.4.4.2"><h5>7.24.4.4.2 The wcscoll function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wcscoll(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscoll function compares the wide string pointed to by s1 to the wide string
pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the
current locale.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscoll function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
-<!--page 392 indent 4-->
+<!--page 392 -->
wide string pointed to by s2 when both are interpreted as appropriate to the current
locale.
<a name="7.24.4.4.3" href="#7.24.4.4.3"><h5>7.24.4.4.3 The wcsncmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wcsncmp(const wchar_t *s1, const wchar_t *s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsncmp function compares not more than n wide characters (those that follow a
null wide character are not compared) from the array pointed to by s1 to the array
pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
<a name="7.24.4.4.4" href="#7.24.4.4.4"><h5>7.24.4.4.4 The wcsxfrm function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcsxfrm(wchar_t * restrict s1,
const wchar_t * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsxfrm function transforms the wide string pointed to by s2 and places the
resulting wide string into the array pointed to by s1. The transformation is such that if
the wcscmp function is applied to two transformed wide strings, it returns a value greater
into the resulting array pointed to by s1, including the terminating null wide character. If
n is zero, s1 is permitted to be a null pointer.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsxfrm function returns the length of the transformed wide string (not including
the terminating null wide character). If the value returned is n or greater, the contents of
the array pointed to by s1 are indeterminate.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The value of the following expression is the length of the array needed to hold the
transformation of the wide string pointed to by s:
-<!--page 393 indent 4-->
+<!--page 393 -->
<pre>
1 + wcsxfrm(NULL, s, 0)</pre>
<a name="7.24.4.4.5" href="#7.24.4.4.5"><h5>7.24.4.4.5 The wmemcmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int wmemcmp(const wchar_t *s1, const wchar_t *s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemcmp function compares the first n wide characters of the object pointed to by
s1 to the first n wide characters of the object pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
pointed to by s2.
<a name="7.24.4.5.1" href="#7.24.4.5.1"><h5>7.24.4.5.1 The wcschr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcschr(const wchar_t *s, wchar_t c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcschr function locates the first occurrence of c in the wide string pointed to by s.
The terminating null wide character is considered to be part of the wide string.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcschr function returns a pointer to the located wide character, or a null pointer if
the wide character does not occur in the wide string.
<a name="7.24.4.5.2" href="#7.24.4.5.2"><h5>7.24.4.5.2 The wcscspn function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcscspn(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscspn function computes the length of the maximum initial segment of the wide
string pointed to by s1 which consists entirely of wide characters not from the wide
string pointed to by s2.
-<!--page 394 indent 4-->
+<!--page 394 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscspn function returns the length of the segment.
<a name="7.24.4.5.3" href="#7.24.4.5.3"><h5>7.24.4.5.3 The wcspbrk function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcspbrk function locates the first occurrence in the wide string pointed to by s1 of
any wide character from the wide string pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcspbrk function returns a pointer to the wide character in s1, or a null pointer if
no wide character from s2 occurs in s1.
<a name="7.24.4.5.4" href="#7.24.4.5.4"><h5>7.24.4.5.4 The wcsrchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsrchr(const wchar_t *s, wchar_t c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsrchr function locates the last occurrence of c in the wide string pointed to by
s. The terminating null wide character is considered to be part of the wide string.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsrchr function returns a pointer to the wide character, or a null pointer if c does
not occur in the wide string.
<a name="7.24.4.5.5" href="#7.24.4.5.5"><h5>7.24.4.5.5 The wcsspn function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcsspn(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsspn function computes the length of the maximum initial segment of the wide
string pointed to by s1 which consists entirely of wide characters from the wide string
pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsspn function returns the length of the segment.
-<!--page 395 indent 4-->
+<!--page 395 -->
<a name="7.24.4.5.6" href="#7.24.4.5.6"><h5>7.24.4.5.6 The wcsstr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsstr function locates the first occurrence in the wide string pointed to by s1 of
the sequence of wide characters (excluding the terminating null wide character) in the
wide string pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsstr function returns a pointer to the located wide string, or a null pointer if the
wide string is not found. If s2 points to a wide string with zero length, the function
returns s1.
<a name="7.24.4.5.7" href="#7.24.4.5.7"><h5>7.24.4.5.7 The wcstok function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wcstok(wchar_t * restrict s1,
const wchar_t * restrict s2,
wchar_t ** restrict ptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A sequence of calls to the wcstok function breaks the wide string pointed to by s1 into
a sequence of tokens, each of which is delimited by a wide character from the wide string
pointed to by s2. The third argument points to a caller-provided wchar_t pointer into
which the wcstok function stores information necessary for it to continue scanning the
same wide string.
-<p><!--para 3-->
+<p><!--para 3 -->
The first call in a sequence has a non-null first argument and stores an initial value in the
object pointed to by ptr. Subsequent calls in the sequence have a null first argument and
the object pointed to by ptr is required to have the value stored by the previous call in
the sequence, which is then updated. The separator wide string pointed to by s2 may be
different from call to call.
-<p><!--para 4-->
+<p><!--para 4 -->
The first call in the sequence searches the wide string pointed to by s1 for the first wide
character that is not contained in the current separator wide string pointed to by s2. If no
such wide character is found, then there are no tokens in the wide string pointed to by s1
and the wcstok function returns a null pointer. If such a wide character is found, it is
the start of the first token.
-<p><!--para 5-->
+<p><!--para 5 -->
The wcstok function then searches from there for a wide character that is contained in
the current separator wide string. If no such wide character is found, the current token
-<!--page 396 indent 4-->
+<!--page 396 -->
extends to the end of the wide string pointed to by s1, and subsequent searches in the
same wide string for a token return a null pointer. If such a wide character is found, it is
overwritten by a null wide character, which terminates the current token.
-<p><!--para 6-->
+<p><!--para 6 -->
In all cases, the wcstok function stores sufficient information in the pointer pointed to
by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer
value for ptr, shall start searching just past the element overwritten by a null wide
character (if any).
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The wcstok function returns a pointer to the first wide character of a token, or a null
pointer if there is no token.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE
<pre>
#include <a href="#7.24"><wchar.h></a>
<a name="7.24.4.5.8" href="#7.24.4.5.8"><h5>7.24.4.5.8 The wmemchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemchr(const wchar_t *s, wchar_t c,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemchr function locates the first occurrence of c in the initial n wide characters of
the object pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemchr function returns a pointer to the located wide character, or a null pointer if
the wide character does not occur in the object.
-<!--page 397 indent 4-->
+<!--page 397 -->
<a name="7.24.4.6" href="#7.24.4.6"><h5>7.24.4.6 Miscellaneous functions</h5></a>
<a name="7.24.4.6.1" href="#7.24.4.6.1"><h5>7.24.4.6.1 The wcslen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcslen(const wchar_t *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcslen function computes the length of the wide string pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcslen function returns the number of wide characters that precede the terminating
null wide character.
<a name="7.24.4.6.2" href="#7.24.4.6.2"><h5>7.24.4.6.2 The wmemset function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemset function copies the value of c into each of the first n wide characters of
the object pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemset function returns the value of s.
<a name="7.24.5" href="#7.24.5"><h4>7.24.5 Wide character time conversion functions</h4></a>
<a name="7.24.5.1" href="#7.24.5.1"><h5>7.24.5.1 The wcsftime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><time.h></a>
#include <a href="#7.24"><wchar.h></a>
const wchar_t * restrict format,
const struct tm * restrict timeptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsftime function is equivalent to the strftime function, except that:
<ul>
<li> The argument s points to the initial element of an array of wide characters into which
the generated output is to be placed.
-<!--page 398 indent 4-->
+<!--page 398 -->
<li> The argument maxsize indicates the limiting number of wide characters.
<li> The argument format is a wide string and the conversion specifiers are replaced by
corresponding sequences of wide characters.
<li> The return value indicates the number of wide characters.
</ul>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the total number of resulting wide characters including the terminating null wide
character is not more than maxsize, the wcsftime function returns the number of
wide characters placed into the array pointed to by s not including the terminating null
indeterminate.
<a name="7.24.6" href="#7.24.6"><h4>7.24.6 Extended multibyte/wide character conversion utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.24"><wchar.h></a> declares an extended set of functions useful for conversion
between multibyte characters and wide characters.
-<p><!--para 2-->
+<p><!--para 2 -->
Most of the following functions -- those that are listed as ''restartable'', <a href="#7.24.6.3">7.24.6.3</a> and
<a href="#7.24.6.4">7.24.6.4</a> -- take as a last argument a pointer to an object of type mbstate_t that is used
to describe the current conversion state from a particular multibyte character sequence to
a wide character sequence (or the reverse) under the rules of a particular setting for the
LC_CTYPE category of the current locale.
-<p><!--para 3-->
+<p><!--para 3 -->
The initial conversion state corresponds, for a conversion in either direction, to the
beginning of a new multibyte character in the initial shift state. A zero-valued
mbstate_t object is (at least) one way to describe an initial conversion state. A zero-
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.<sup><a href="#note299"><b>299)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 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
-<!--page 399 indent 4-->
+<!--page 399 -->
<h6>footnotes</h6>
<p><small><a name="note299" href="#note299">299)</a> Thus, a particular mbstate_t object can be used, for example, with both the mbrtowc and
<a name="7.24.6.1.1" href="#7.24.6.1.1"><h5>7.24.6.1.1 The btowc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
wint_t btowc(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The btowc function determines whether c constitutes a valid single-byte character in the
initial shift state.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The btowc function returns WEOF if c has the value EOF or if (unsigned char)c
does not constitute a valid single-byte character in the initial shift state. Otherwise, it
returns the wide character representation of that character.
<a name="7.24.6.1.2" href="#7.24.6.1.2"><h5>7.24.6.1.2 The wctob function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stdio.h></a>
#include <a href="#7.24"><wchar.h></a>
int wctob(wint_t c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wctob function determines whether c corresponds to a member of the extended
character set whose multibyte character representation is a single byte when in the initial
shift state.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wctob function returns EOF if c does not correspond to a multibyte character with
length one in the initial shift state. Otherwise, it returns the single-byte representation of
that character as an unsigned char converted to an int.
<a name="7.24.6.2.1" href="#7.24.6.2.1"><h5>7.24.6.2.1 The mbsinit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
int mbsinit(const mbstate_t *ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If ps is not a null pointer, the mbsinit function determines whether the pointed-to
mbstate_t object describes an initial conversion state.
-<!--page 400 indent 4-->
+<!--page 400 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mbsinit function returns nonzero if ps is a null pointer or if the pointed-to object
describes an initial conversion state; otherwise, it returns zero.
<a name="7.24.6.3" href="#7.24.6.3"><h5>7.24.6.3 Restartable multibyte/wide character conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
These functions differ from the corresponding multibyte character functions of <a href="#7.20.7">7.20.7</a>
(mblen, mbtowc, and wctomb) in that they have an extra parameter, ps, of type
pointer to mbstate_t that points to an object that can completely describe the current
each function uses its own internal mbstate_t object instead, which is initialized at
program startup to the initial conversion state. The implementation behaves as if no
library function calls these functions with a null pointer for ps.
-<p><!--para 2-->
+<p><!--para 2 -->
Also unlike their corresponding functions, the return value does not represent whether the
encoding is state-dependent.
<a name="7.24.6.3.1" href="#7.24.6.3.1"><h5>7.24.6.3.1 The mbrlen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbrlen(const char * restrict s,
size_t n,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mbrlen function is equivalent to the call:
<pre>
mbrtowc(NULL, s, n, ps != NULL ? ps : &internal)</pre>
where internal is the mbstate_t object for the mbrlen function, except that the
expression designated by ps is evaluated only once.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mbrlen function returns a value between zero and n, inclusive, (size_t)(-2),
or (size_t)(-1).
<p><b> Forward references</b>: the mbrtowc function (<a href="#7.24.6.3.2">7.24.6.3.2</a>).
-<!--page 401 indent 4-->
+<!--page 401 -->
<a name="7.24.6.3.2" href="#7.24.6.3.2"><h5>7.24.6.3.2 The mbrtowc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbrtowc(wchar_t * restrict pwc,
size_t n,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is a null pointer, the mbrtowc function is equivalent to the call:
<pre>
mbrtowc(NULL, "", 1, ps)</pre>
In this case, the values of the parameters pwc and n are ignored.
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, the mbrtowc function inspects at most n bytes beginning with
the byte pointed to by s to determine the number of bytes needed to complete the next
multibyte character (including any shift sequences). If the function determines that the
the object pointed to by pwc. If the corresponding wide character is the null wide
character, the resulting state described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The mbrtowc function returns the first of the following that applies (given the current
conversion state):
0 if the next n or fewer bytes complete the multibyte character that
value is stored); the value of the macro EILSEQ is stored in errno,
and the conversion state is unspecified.</pre>
-<!--page 402 indent 4-->
+<!--page 402 -->
<h6>footnotes</h6>
<p><small><a name="note300" href="#note300">300)</a> When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a
<a name="7.24.6.3.3" href="#7.24.6.3.3"><h5>7.24.6.3.3 The wcrtomb function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcrtomb(char * restrict s,
wchar_t wc,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is a null pointer, the wcrtomb function is equivalent to the call
<pre>
wcrtomb(buf, L'\0', ps)</pre>
where buf is an internal buffer.
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, the wcrtomb function determines the number of bytes needed
to represent the multibyte character that corresponds to the wide character given by wc
(including any shift sequences), and stores the multibyte character representation in the
wc is a null wide character, a null byte is stored, preceded by any shift sequence needed
to restore the initial shift state; the resulting state described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The wcrtomb function returns the number of bytes stored in the array object (including
any shift sequences). When wc is not a valid wide character, an encoding error occurs:
the function stores the value of the macro EILSEQ in errno and returns
(size_t)(-1); the conversion state is unspecified.
<a name="7.24.6.4" href="#7.24.6.4"><h5>7.24.6.4 Restartable multibyte/wide string conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
These functions differ from the corresponding multibyte string functions of <a href="#7.20.8">7.20.8</a>
(mbstowcs and wcstombs) in that they have an extra parameter, ps, of type pointer to
mbstate_t that points to an object that can completely describe the current conversion
uses its own internal mbstate_t object instead, which is initialized at program startup
to the initial conversion state. The implementation behaves as if no library function calls
these functions with a null pointer for ps.
-<p><!--para 2-->
+<p><!--para 2 -->
Also unlike their corresponding functions, the conversion source parameter, src, has a
pointer-to-pointer type. When the function is storing the results of conversions (that is,
when dst is not a null pointer), the pointer object pointed to by this parameter is updated
to reflect the amount of the source processed by that invocation.
-<!--page 403 indent 4-->
+<!--page 403 -->
<a name="7.24.6.4.1" href="#7.24.6.4.1"><h5>7.24.6.4.1 The mbsrtowcs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t mbsrtowcs(wchar_t * restrict dst,
size_t len,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mbsrtowcs function converts a sequence of multibyte characters that begins in the
conversion state described by the object pointed to by ps, from the array indirectly
pointed to by src into a sequence of corresponding wide characters. If dst is not a null
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.<sup><a href="#note301"><b>301)</b></a></sup> Each conversion takes
place as if by a call to the mbrtowc function.
-<p><!--para 3-->
+<p><!--para 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
just past the last multibyte character converted (if any). If conversion stopped due to
reaching a terminating null character and if dst is not a null pointer, the resulting state
described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If the input conversion encounters a sequence of bytes that do not form a valid multibyte
character, an encoding error occurs: the mbsrtowcs function stores the value of the
macro EILSEQ in errno and returns (size_t)(-1); the conversion state is
-<!--page 404 indent 4-->
+<!--page 404 -->
<h6>footnotes</h6>
<p><small><a name="note301" href="#note301">301)</a> Thus, the value of len is ignored if dst is a null pointer.
<a name="7.24.6.4.2" href="#7.24.6.4.2"><h5>7.24.6.4.2 The wcsrtombs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.24"><wchar.h></a>
size_t wcsrtombs(char * restrict dst,
size_t len,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsrtombs function converts a sequence of wide characters from the array
indirectly pointed to by src into a sequence of corresponding multibyte characters that
begins in the conversion state described by the object pointed to by ps. If dst is not a
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.<sup><a href="#note302"><b>302)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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
reaching a terminating null wide character, the resulting state described is the initial
conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If conversion stops because a wide character is reached that does not correspond to a
valid multibyte character, an encoding error occurs: the wcsrtombs function stores the
value of the macro EILSEQ in errno and returns (size_t)(-1); the conversion
-<!--page 405 indent 4-->
+<!--page 405 -->
<h6>footnotes</h6>
<p><small><a name="note302" href="#note302">302)</a> If conversion stops because a terminating null wide character has been reached, the bytes stored
<a name="7.25" href="#7.25"><h3>7.25 Wide character classification and mapping utilities <wctype.h></h3></a>
<a name="7.25.1" href="#7.25.1"><h4>7.25.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 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>
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are
<pre>
wint_t</pre>
wctype_t</pre>
which is a scalar type that can hold values which represent locale-specific character
classifications.
-<p><!--para 3-->
+<p><!--para 3 -->
The macro defined is WEOF (described in <a href="#7.24.1">7.24.1</a>).
-<p><!--para 4-->
+<p><!--para 4 -->
The functions declared are grouped as follows:
<ul>
<li> Functions that provide wide character classification;
<li> Functions that provide wide character case mapping;
<li> Extensible functions that provide wide character mapping.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
For all functions described in this subclause that accept an argument of type wint_t, the
value shall be representable as a wchar_t or shall equal the value of the macro WEOF. If
this argument has any other value, the behavior is undefined.
-<p><!--para 6-->
+<p><!--para 6 -->
The behavior of these functions is affected by the LC_CTYPE category of the current
locale.
-<!--page 406 indent 4-->
+<!--page 406 -->
<h6>footnotes</h6>
<p><small><a name="note303" href="#note303">303)</a> See ''future library directions'' (<a href="#7.26.13">7.26.13</a>).
</small>
<a name="7.25.2" href="#7.25.2"><h4>7.25.2 Wide character classification utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.25"><wctype.h></a> declares several functions useful for classifying wide
characters.
-<p><!--para 2-->
+<p><!--para 2 -->
The term printing wide character refers to a member of a locale-specific set of wide
characters, each of which occupies at least one printing position on a display device. The
term control wide character refers to a member of a locale-specific set of wide characters
that are not printing wide characters.
<a name="7.25.2.1" href="#7.25.2.1"><h5>7.25.2.1 Wide character classification functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions in this subclause return nonzero (true) if and only if the value of the
argument wc conforms to that in the description of the function.
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the following functions returns true for each wide character that corresponds (as
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
<a name="7.25.2.1.1" href="#7.25.2.1.1"><h5>7.25.2.1.1 The iswalnum function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswalnum(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswalnum function tests for any wide character for which iswalpha or
iswdigit is true.
<a name="7.25.2.1.2" href="#7.25.2.1.2"><h5>7.25.2.1.2 The iswalpha function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswalpha(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswalpha function tests for any wide character for which iswupper or
iswlower is true, or any wide character that is one of a locale-specific set of alphabetic
-<!--page 407 indent 4-->
+<!--page 407 -->
wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace
is true.<sup><a href="#note305"><b>305)</b></a></sup>
<a name="7.25.2.1.3" href="#7.25.2.1.3"><h5>7.25.2.1.3 The iswblank function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswblank(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswblank function tests for any wide character that is a standard blank wide
character or is one of a locale-specific set of wide characters for which iswspace is true
and that is used to separate words within a line of text. The standard blank wide
<a name="7.25.2.1.4" href="#7.25.2.1.4"><h5>7.25.2.1.4 The iswcntrl function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswcntrl(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswcntrl function tests for any control wide character.
<a name="7.25.2.1.5" href="#7.25.2.1.5"><h5>7.25.2.1.5 The iswdigit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswdigit(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswdigit function tests for any wide character that corresponds to a decimal-digit
character (as defined in <a href="#5.2.1">5.2.1</a>).
<a name="7.25.2.1.6" href="#7.25.2.1.6"><h5>7.25.2.1.6 The iswgraph function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswgraph(wint_t wc);</pre>
-<!--page 408 indent 4-->
+<!--page 408 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswgraph function tests for any wide character for which iswprint is true and
iswspace is false.<sup><a href="#note306"><b>306)</b></a></sup>
<a name="7.25.2.1.7" href="#7.25.2.1.7"><h5>7.25.2.1.7 The iswlower function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswlower(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswlower function tests for any wide character that corresponds to a lowercase
letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
iswdigit, iswpunct, or iswspace is true.
<a name="7.25.2.1.8" href="#7.25.2.1.8"><h5>7.25.2.1.8 The iswprint function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswprint(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswprint function tests for any printing wide character.
<a name="7.25.2.1.9" href="#7.25.2.1.9"><h5>7.25.2.1.9 The iswpunct function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswpunct(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswpunct function tests for any printing wide character that is one of a locale-
specific set of punctuation wide characters for which neither iswspace nor iswalnum
is true.306)
<a name="7.25.2.1.10" href="#7.25.2.1.10"><h5>7.25.2.1.10 The iswspace function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswspace(wint_t wc);</pre>
-<!--page 409 indent 4-->
+<!--page 409 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswspace function tests for any wide character that corresponds to a locale-specific
set of white-space wide characters for which none of iswalnum, iswgraph, or
iswpunct is true.
<a name="7.25.2.1.11" href="#7.25.2.1.11"><h5>7.25.2.1.11 The iswupper function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswupper(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswupper function tests for any wide character that corresponds to an uppercase
letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
iswdigit, iswpunct, or iswspace is true.
<a name="7.25.2.1.12" href="#7.25.2.1.12"><h5>7.25.2.1.12 The iswxdigit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswxdigit(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswxdigit function tests for any wide character that corresponds to a
hexadecimal-digit character (as defined in <a href="#6.4.4.1">6.4.4.1</a>).
<a name="7.25.2.2" href="#7.25.2.2"><h5>7.25.2.2 Extensible wide character classification functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions wctype and iswctype provide extensible wide character classification
as well as testing equivalent to that performed by the functions described in the previous
subclause (<a href="#7.25.2.1">7.25.2.1</a>).
<a name="7.25.2.2.1" href="#7.25.2.2.1"><h5>7.25.2.2.1 The iswctype function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
int iswctype(wint_t wc, wctype_t desc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswctype function determines whether the wide character wc has the property
described by desc. The current setting of the LC_CTYPE category shall be the same as
during the call to wctype that returned the value desc.
-<p><!--para 3-->
+<p><!--para 3 -->
Each of the following expressions has a truth-value equivalent to the call to the wide
character classification function (<a href="#7.25.2.1">7.25.2.1</a>) in the comment that follows the expression:
-<!--page 410 indent 4-->
+<!--page 410 -->
<pre>
iswctype(wc, wctype("alnum")) // iswalnum(wc)
iswctype(wc, wctype("alpha")) // iswalpha(wc)
iswctype(wc, wctype("upper")) // iswupper(wc)
iswctype(wc, wctype("xdigit")) // iswxdigit(wc)</pre>
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The iswctype function returns nonzero (true) if and only if the value of the wide
character wc has the property described by desc.
<p><b> Forward references</b>: the wctype function (<a href="#7.25.2.2.2">7.25.2.2.2</a>).
<a name="7.25.2.2.2" href="#7.25.2.2.2"><h5>7.25.2.2.2 The wctype function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
wctype_t wctype(const char *property);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wctype function constructs a value with type wctype_t that describes a class of
wide characters identified by the string argument property.
-<p><!--para 3-->
+<p><!--para 3 -->
The strings listed in the description of the iswctype function shall be valid in all
locales as property arguments to the wctype function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If property identifies a valid class of wide characters according to the LC_CTYPE
category of the current locale, the wctype function returns a nonzero value that is valid
as the second argument to the iswctype function; otherwise, it returns zero. *
-<!--page 411 indent 4-->
+<!--page 411 -->
<a name="7.25.3" href="#7.25.3"><h4>7.25.3 Wide character case mapping utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.25"><wctype.h></a> declares several functions useful for mapping wide characters.
<a name="7.25.3.1" href="#7.25.3.1"><h5>7.25.3.1 Wide character case mapping functions</h5></a>
<a name="7.25.3.1.1" href="#7.25.3.1.1"><h5>7.25.3.1.1 The towlower function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
wint_t towlower(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The towlower function converts an uppercase letter to a corresponding lowercase letter.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a wide character for which iswupper is true and there are one or
more corresponding wide characters, as specified by the current locale, for which
iswlower is true, the towlower function returns one of the corresponding wide
<a name="7.25.3.1.2" href="#7.25.3.1.2"><h5>7.25.3.1.2 The towupper function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
wint_t towupper(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The towupper function converts a lowercase letter to a corresponding uppercase letter.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a wide character for which iswlower is true and there are one or
more corresponding wide characters, as specified by the current locale, for which
iswupper is true, the towupper function returns one of the corresponding wide
returned unchanged.
<a name="7.25.3.2" href="#7.25.3.2"><h5>7.25.3.2 Extensible wide character case mapping functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions wctrans and towctrans provide extensible wide character mapping as
well as case mapping equivalent to that performed by the functions described in the
previous subclause (<a href="#7.25.3.1">7.25.3.1</a>).
-<!--page 412 indent 4-->
+<!--page 412 -->
<a name="7.25.3.2.1" href="#7.25.3.2.1"><h5>7.25.3.2.1 The towctrans function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
wint_t towctrans(wint_t wc, wctrans_t desc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The towctrans function maps the wide character wc using the mapping described by
desc. The current setting of the LC_CTYPE category shall be the same as during the call
to wctrans that returned the value desc.
-<p><!--para 3-->
+<p><!--para 3 -->
Each of the following expressions behaves the same as the call to the wide character case
mapping function (<a href="#7.25.3.1">7.25.3.1</a>) in the comment that follows the expression:
<pre>
towctrans(wc, wctrans("tolower")) // towlower(wc)
towctrans(wc, wctrans("toupper")) // towupper(wc)</pre>
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The towctrans function returns the mapped value of wc using the mapping described
by desc.
<a name="7.25.3.2.2" href="#7.25.3.2.2"><h5>7.25.3.2.2 The wctrans function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><wctype.h></a>
wctrans_t wctrans(const char *property);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wctrans function constructs a value with type wctrans_t that describes a
mapping between wide characters identified by the string argument property.
-<p><!--para 3-->
+<p><!--para 3 -->
The strings listed in the description of the towctrans function shall be valid in all
locales as property arguments to the wctrans function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If property identifies a valid mapping of wide characters according to the LC_CTYPE
category of the current locale, the wctrans function returns a nonzero value that is valid
as the second argument to the towctrans function; otherwise, it returns zero.
-<!--page 413 indent 4-->
+<!--page 413 -->
<a name="7.26" href="#7.26"><h3>7.26 Future library directions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following names are grouped under individual headers for convenience. All external
names described below are reserved no matter what headers are included by the program.
<a name="7.26.1" href="#7.26.1"><h4>7.26.1 Complex arithmetic <complex.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The function names
<pre>
cerf cexpm1 clog2
<a href="#7.3"><complex.h></a> header.
<a name="7.26.2" href="#7.26.2"><h4>7.26.2 Character handling <ctype.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with either is or to, and a lowercase letter may be added to
the declarations in the <a href="#7.4"><ctype.h></a> header.
<a name="7.26.3" href="#7.26.3"><h4>7.26.3 Errors <errno.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macros that begin with E and a digit or E and an uppercase letter may be added to the
declarations in the <a href="#7.5"><errno.h></a> header.
<a name="7.26.4" href="#7.26.4"><h4>7.26.4 Format conversion of integer types <inttypes.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macro names beginning with PRI or SCN followed by any lowercase letter or X may be
added to the macros defined in the <a href="#7.8"><inttypes.h></a> header.
<a name="7.26.5" href="#7.26.5"><h4>7.26.5 Localization <locale.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macros that begin with LC_ and an uppercase letter may be added to the definitions in
the <a href="#7.11"><locale.h></a> header.
<a name="7.26.6" href="#7.26.6"><h4>7.26.6 Signal handling <signal.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macros that begin with either SIG and an uppercase letter or SIG_ and an uppercase
letter may be added to the definitions in the <a href="#7.14"><signal.h></a> header.
<a name="7.26.7" href="#7.26.7"><h4>7.26.7 Boolean type and values <stdbool.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The ability to undefine and perhaps then redefine the macros bool, true, and false is
an obsolescent feature.
<a name="7.26.8" href="#7.26.8"><h4>7.26.8 Integer types <stdint.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Typedef names beginning with int or uint and ending with _t may be added to the
types defined in the <a href="#7.18"><stdint.h></a> header. Macro names beginning with INT or UINT
and ending with _MAX, _MIN, or _C may be added to the macros defined in the
<a href="#7.18"><stdint.h></a> header.
-<!--page 414 indent 4-->
+<!--page 414 -->
<a name="7.26.9" href="#7.26.9"><h4>7.26.9 Input/output <stdio.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Lowercase letters may be added to the conversion specifiers and length modifiers in
fprintf and fscanf. Other characters may be used in extensions.
-<p><!--para 2-->
+<p><!--para 2 -->
The gets function is obsolescent, and is deprecated.
-<p><!--para 3-->
+<p><!--para 3 -->
The use of ungetc on a binary stream where the file position indicator is zero prior to
the call is an obsolescent feature.
<a name="7.26.10" href="#7.26.10"><h4>7.26.10 General utilities <stdlib.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with str and a lowercase letter may be added to the
declarations in the <a href="#7.20"><stdlib.h></a> header.
<a name="7.26.11" href="#7.26.11"><h4>7.26.11 String handling <string.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with str, mem, or wcs and a lowercase letter may be added
to the declarations in the <a href="#7.21"><string.h></a> header.
<a name="7.26.12" href="#7.26.12"><h4>7.26.12 Extended multibyte and wide character utilities <wchar.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with wcs and a lowercase letter may be added to the
declarations in the <a href="#7.24"><wchar.h></a> header.
-<p><!--para 2-->
+<p><!--para 2 -->
Lowercase letters may be added to the conversion specifiers and length modifiers in
fwprintf and fwscanf. Other characters may be used in extensions.
<a name="7.26.13" href="#7.26.13"><h4>7.26.13 Wide character classification and mapping utilities</h4></a>
<a href="#7.25"><wctype.h></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with is or to and a lowercase letter may be added to the
declarations in the <a href="#7.25"><wctype.h></a> header.
-<!--page 415 indent 4-->
+<!--page 415 -->
<a name="A" href="#A"><h2>Annex A</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Language syntax summary</pre>
<a name="A.1.2" href="#A.1.2"><h4>A.1.2 Keywords</h4></a>
(<a href="#6.4.1">6.4.1</a>) keyword: one of
-<!--page 416 indent 0-->
+<!--page 416 -->
<pre>
auto enum restrict unsigned
break extern return void
octal-constant integer-suffixopt
hexadecimal-constant integer-suffixopt</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) decimal-constant:
-<!--page 417 indent 0-->
+<!--page 417 -->
<pre>
nonzero-digit
decimal-constant digit</pre>
decimal-floating-constant
hexadecimal-floating-constant</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) decimal-floating-constant:
-<!--page 418 indent 0-->
+<!--page 418 -->
<pre>
fractional-constant exponent-partopt floating-suffixopt
digit-sequence exponent-part floating-suffixopt</pre>
<pre>
identifier</pre>
(<a href="#6.4.4.4">6.4.4.4</a>) character-constant:
-<!--page 419 indent 0-->
+<!--page 419 -->
<pre>
' c-char-sequence '
L' c-char-sequence '</pre>
s-char
s-char-sequence s-char</pre>
(<a href="#6.4.5">6.4.5</a>) s-char:
-<!--page 420 indent 0-->
+<!--page 420 -->
<pre>
any member of the source character set except
the double-quote ", backslash \, or new-line character
<a name="A.1.9" href="#A.1.9"><h4>A.1.9 Preprocessing numbers</h4></a>
(<a href="#6.4.8">6.4.8</a>) pp-number:
-<!--page 421 indent 0-->
+<!--page 421 -->
<pre>
digit
. digit
unary-expression
( type-name ) cast-expression</pre>
(<a href="#6.5.5">6.5.5</a>) multiplicative-expression:
-<!--page 422 indent 0-->
+<!--page 422 -->
<pre>
cast-expression
multiplicative-expression * cast-expression
logical-AND-expression
logical-OR-expression || logical-AND-expression</pre>
(<a href="#6.5.15">6.5.15</a>) conditional-expression:
-<!--page 423 indent 0-->
+<!--page 423 -->
<pre>
logical-OR-expression
logical-OR-expression ? expression : conditional-expression</pre>
declarator
declarator = initializer</pre>
(<a href="#6.7.1">6.7.1</a>) storage-class-specifier:
-<!--page 424 indent 0-->
+<!--page 424 -->
<pre>
typedef
extern
struct-declarator
struct-declarator-list , struct-declarator</pre>
(<a href="#6.7.2.1">6.7.2.1</a>) struct-declarator:
-<!--page 425 indent 0-->
+<!--page 425 -->
<pre>
declarator
declaratoropt : constant-expression</pre>
type-qualifier
type-qualifier-list type-qualifier</pre>
(<a href="#6.7.5">6.7.5</a>) parameter-type-list:
-<!--page 426 indent 0-->
+<!--page 426 -->
<pre>
parameter-list
parameter-list , ...</pre>
designationopt initializer
initializer-list , designationopt initializer</pre>
(<a href="#6.7.8">6.7.8</a>) designation:
-<!--page 427 indent 0-->
+<!--page 427 -->
<pre>
designator-list =</pre>
(<a href="#6.7.8">6.7.8</a>) designator-list:
<pre>
expressionopt ;</pre>
(<a href="#6.8.4">6.8.4</a>) selection-statement:
-<!--page 428 indent 0-->
+<!--page 428 -->
<pre>
if ( expression ) statement
if ( expression ) statement else statement
text-line
# non-directive</pre>
(<a href="#6.10">6.10</a>) if-section:
-<!--page 429 indent 0-->
+<!--page 429 -->
<pre>
if-group elif-groupsopt else-groupopt endif-line</pre>
(<a href="#6.10">6.10</a>) if-group:
<pre>
a ( character not immediately preceded by white-space</pre>
(<a href="#6.10">6.10</a>) replacement-list:
-<!--page 430 indent 0-->
+<!--page 430 -->
<pre>
pp-tokensopt</pre>
(<a href="#6.10">6.10</a>) pp-tokens:
preprocessing-token
pp-tokens preprocessing-token</pre>
(<a href="#6.10">6.10</a>) new-line:
-<!--page 431 indent 0-->
+<!--page 431 -->
<pre>
the new-line character</pre>
void assert(scalar expression);</pre>
<a name="B.2" href="#B.2"><h3>B.2 Complex <complex.h></h3></a>
-<!--page 432 indent -1-->
-<!--page 433 indent 0-->
+<!--page 432 -->
+<!--page 433 -->
<pre>
complex imaginary I
_Complex_I _Imaginary_I
EDOM EILSEQ ERANGE errno</pre>
<a name="B.5" href="#B.5"><h3>B.5 Floating-point environment <fenv.h></h3></a>
-<!--page 434 indent 0-->
+<!--page 434 -->
<pre>
fenv_t FE_OVERFLOW FE_TOWARDZERO
fexcept_t FE_UNDERFLOW FE_UPWARD
FLT_MIN_EXP LDBL_MAX_10_EXP</pre>
<a name="B.7" href="#B.7"><h3>B.7 Format conversion of integer types <inttypes.h></h3></a>
-<!--page 435 indent 0-->
+<!--page 435 -->
<pre>
imaxdiv_t
PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR
struct lconv *localeconv(void);</pre>
<a name="B.11" href="#B.11"><h3>B.11 Mathematics <math.h></h3></a>
-<!--page 436 indent -1-->
-<!--page 437 indent -1-->
-<!--page 438 indent -1-->
-<!--page 439 indent -1-->
-<!--page 440 indent 0-->
+<!--page 436 -->
+<!--page 437 -->
+<!--page 438 -->
+<!--page 439 -->
+<!--page 440 -->
<pre>
float_t FP_INFINITE FP_FAST_FMAL
double_t FP_NAN FP_ILOGB0
void va_start(va_list ap, parmN);</pre>
<a name="B.15" href="#B.15"><h3>B.15 Boolean type and values <stdbool.h></h3></a>
-<!--page 441 indent 0-->
+<!--page 441 -->
<pre>
bool
true
UINTN_MAX PTRDIFF_MIN</pre>
<a name="B.18" href="#B.18"><h3>B.18 Input/output <stdio.h></h3></a>
-<!--page 442 indent -1-->
-<!--page 443 indent 0-->
+<!--page 442 -->
+<!--page 443 -->
<pre>
size_t _IOLBF FILENAME_MAX TMP_MAX
FILE _IONBF L_tmpnam stderr
void perror(const char *s);</pre>
<a name="B.19" href="#B.19"><h3>B.19 General utilities <stdlib.h></h3></a>
-<!--page 444 indent -1-->
-<!--page 445 indent 0-->
+<!--page 444 -->
+<!--page 445 -->
<pre>
size_t ldiv_t EXIT_FAILURE MB_CUR_MAX
wchar_t lldiv_t EXIT_SUCCESS
const wchar_t * restrict pwcs, size_t n);</pre>
<a name="B.20" href="#B.20"><h3>B.20 String handling <string.h></h3></a>
-<!--page 446 indent 0-->
+<!--page 446 -->
<pre>
size_t
NULL
pow fmin nearbyint creal</pre>
<a name="B.22" href="#B.22"><h3>B.22 Date and time <time.h></h3></a>
-<!--page 447 indent 0-->
+<!--page 447 -->
<pre>
NULL size_t time_t
CLOCKS_PER_SEC clock_t struct tm
const struct tm * restrict timeptr);</pre>
<a name="B.23" href="#B.23"><h3>B.23 Extended multibyte/wide character utilities <wchar.h></h3></a>
-<!--page 448 indent -1-->
-<!--page 449 indent 0-->
+<!--page 448 -->
+<!--page 449 -->
<pre>
wchar_t wint_t WCHAR_MAX
size_t struct tm WCHAR_MIN
mbstate_t * restrict ps);</pre>
<a name="B.24" href="#B.24"><h3>B.24 Wide character classification and mapping utilities <wctype.h></h3></a>
-<!--page 450 indent -1-->
-<!--page 451 indent 4-->
+<!--page 450 -->
+<!--page 451 -->
<pre>
wint_t wctrans_t wctype_t WEOF
int iswalnum(wint_t wc);
wctrans_t wctrans(const char *property);</pre>
<a name="C" href="#C"><h2>Annex C</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Sequence points</pre>
<li> Immediately before and immediately after each call to a comparison function, and
also between any call to a comparison function and any movement of the objects
passed as arguments to that call (<a href="#7.20.5">7.20.5</a>).
-<!--page 452 indent 4-->
+<!--page 452 -->
</ul>
<a name="D" href="#D"><h2>Annex D</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(normative)
Universal character names for identifiers</pre>
This clause lists the hexadecimal code values that are valid in universal character names
in identifiers.
-<p><!--para 2-->
+<p><!--para 2 -->
This table is reproduced unchanged from ISO/IEC TR 10176:1998, produced by ISO/IEC
JTC 1/SC 22/WG 20, except for the omission of ranges that are part of the basic character
sets.
0AAA-0AB0, 0AB2-0AB3, 0AB5-0AB9, 0ABD-0AC5,
0AC7-0AC9, 0ACB-0ACD, 0AD0, 0AE0</pre>
Oriya: 0B01-0B03, 0B05-0B0C, 0B0F-0B10, 0B13-0B28, 0B2A-0B30,
-<!--page 453 indent 0-->
+<!--page 453 -->
<pre>
0B32-0B33, 0B36-0B39, 0B3E-0B43, 0B47-0B48, 0B4B-0B4D,
0B5C-0B5D, 0B5F-0B61</pre>
0AE6-0AEF, 0B66-0B6F, 0BE7-0BEF, 0C66-0C6F, 0CE6-0CEF,
0D66-0D6F, 0E50-0E59, 0ED0-0ED9, 0F20-0F33</pre>
Special characters: 00B5, 00B7, 02B0-02B8, 02BB, 02BD-02C1, 02D0-02D1,
-<!--page 454 indent 4-->
+<!--page 454 -->
<pre>
02E0-02E4, 037A, 0559, 093D, 0B3D, 1FBE, 203F-2040, 2102,
2107, 210A-2113, 2115, 2118-211D, 2124, 2126, 2128, 212A-2131,
2133-2138, 2160-2182, 3005-3007, 3021-3029</pre>
<a name="E" href="#E"><h2>Annex E</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Implementation limits</pre>
minimum magnitudes shown shall be replaced by implementation-defined magnitudes
with the same sign. The values shall all be constant expressions suitable for use in #if
preprocessing directives. The components are described further in <a href="#5.2.4.2.1">5.2.4.2.1</a>.
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
#define CHAR_BIT 8
#define CHAR_MAX UCHAR_MAX or SCHAR_MAX
FLT_ROUNDS, shall be constant expressions suitable for use in #if preprocessing
directives; all floating values shall be constant expressions. The components are
described further in <a href="#5.2.4.2.2">5.2.4.2.2</a>.
-<p><!--para 3-->
+<p><!--para 3 -->
The values given in the following list shall be replaced by implementation-defined
expressions:
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
#define FLT_EVAL_METHOD
#define FLT_ROUNDS</pre>
The values given in the following list shall be replaced by implementation-defined
constant expressions that are greater or equal in magnitude (absolute value) to those
shown, with the same sign:
-<!--page 455 indent 4-->
-<p><!--para 5-->
+<!--page 455 -->
+<p><!--para 5 -->
<pre>
#define DBL_DIG 10
#define DBL_MANT_DIG
#define LDBL_MIN_EXP</pre>
The values given in the following list shall be replaced by implementation-defined
constant expressions with values that are greater than or equal to those shown:
-<p><!--para 6-->
+<p><!--para 6 -->
<pre>
#define DBL_MAX 1E+37
#define FLT_MAX 1E+37
#define LDBL_MAX 1E+37</pre>
The values given in the following list shall be replaced by implementation-defined
constant expressions with (positive) values that are less than or equal to those shown:
-<!--page 456 indent 4-->
+<!--page 456 -->
<pre>
#define DBL_EPSILON 1E-9
#define DBL_MIN 1E-37
IEC 60559 floating-point arithmetic</pre>
<a name="F.1" href="#F.1"><h3>F.1 Introduction</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This annex specifies C language support for the IEC 60559 floating-point standard. The
IEC 60559 floating-point standard is specifically Binary floating-point arithmetic for
microprocessor systems, second edition (IEC 60559:1989), previously designated
behavior is adopted by reference, unless stated otherwise.
<a name="F.2" href="#F.2"><h3>F.2 Types</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The C floating types match the IEC 60559 formats as follows:
<ul>
<li> The float type matches the IEC 60559 single 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.<sup><a href="#note308"><b>308)</b></a></sup>
Recommended practice
-<p><!--para 2-->
+<p><!--para 2 -->
The long double type should match an IEC 60559 extended format.
-<!--page 457 indent 4-->
+<!--page 457 -->
<h6>footnotes</h6>
<p><small><a name="note307" href="#note307">307)</a> ''Extended'' is IEC 60559's double-extended data format. Extended refers to both the common 80-bit
</small>
<a name="F.2.1" href="#F.2.1"><h4>F.2.1 Infinities, signed zeros, and NaNs</h4></a>
-<p><!--para 1-->
+<p><!--para 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.
</small>
<a name="F.3" href="#F.3"><h3>F.3 Operators and functions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
C operators and functions provide IEC 60559 required and recommended facilities as
listed below.
<ul>
strtold function in <a href="#7.20"><stdlib.h></a> provides the conv function recommended in the
Appendix to ANSI/IEEE 854.
-<!--page 458 indent 0-->
+<!--page 458 -->
<li> The relational and equality operators provide IEC 60559 comparisons. IEC 60559
identifies a need for additional comparison predicates to facilitate writing code that
accounts for NaNs. The comparison macros (isgreater, isgreaterequal,
the Appendix to IEC 60559.
<li> The isnan macro in <a href="#7.12"><math.h></a> provides the isnan function recommended in the
Appendix to IEC 60559.
-<!--page 459 indent 4-->
+<!--page 459 -->
<li> The signbit macro and the fpclassify macro in <a href="#7.12"><math.h></a>, used in
conjunction with the number classification macros (FP_NAN, FP_INFINITE,
FP_NORMAL, FP_SUBNORMAL, FP_ZERO), provide the facility of the class
</ul>
<a name="F.4" href="#F.4"><h3>F.4 Floating to integer conversion</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
If the floating value is infinite or NaN or if the integral part of the floating value exceeds
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
</small>
<a name="F.5" href="#F.5"><h3>F.5 Binary-decimal conversion</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Conversion from the widest supported IEC 60559 format to decimal with
DECIMAL_DIG digits and back is the identity function.<sup><a href="#note311"><b>311)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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
rounding mode), which assures that conversion from the widest supported IEC 60559
format to decimal with DECIMAL_DIG digits and back is the identity function.
-<p><!--para 3-->
+<p><!--para 3 -->
Functions such as strtod that convert character sequences to floating types honor the
rounding direction. Hence, if the rounding direction might be upward or downward, the
implementation cannot convert a minus-signed sequence by negating the converted
-<!--page 460 indent 4-->
+<!--page 460 -->
<h6>footnotes</h6>
<p><small><a name="note311" href="#note311">311)</a> If the minimum-width IEC 60559 extended format (64 bits of precision) is supported,
</small>
<a name="F.6" href="#F.6"><h3>F.6 Contracted expressions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A contracted expression treats infinities, NaNs, signed zeros, subnormals, and the
rounding directions in a manner consistent with the basic arithmetic operations covered
by IEC 60559.
Recommended practice
-<p><!--para 2-->
+<p><!--para 2 -->
A contracted expression should raise floating-point exceptions in a manner generally
consistent with the basic arithmetic operations. A contracted expression should deliver
the same value as its uncontracted counterpart, else should be correctly rounded (once).
<a name="F.7" href="#F.7"><h3>F.7 Floating-point environment</h3></a>
-<p><!--para 1-->
+<p><!--para 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
</small>
<a name="F.7.1" href="#F.7.1"><h4>F.7.1 Environment management</h4></a>
-<p><!--para 1-->
+<p><!--para 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
</small>
<a name="F.7.2" href="#F.7.2"><h4>F.7.2 Translation</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
During translation the IEC 60559 default modes are in effect:
<ul>
<li> The rounding direction mode is rounding to nearest.
<li> Trapping or stopping (if supported) is disabled on all floating-point exceptions.
</ul>
Recommended practice
-<p><!--para 2-->
+<p><!--para 2 -->
The implementation should produce a diagnostic message for each translation-time
-<!--page 461 indent 4-->
+<!--page 461 -->
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.
</small>
<a name="F.7.3" href="#F.7.3"><h4>F.7.3 Execution</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
At program startup the floating-point environment is initialized as prescribed by
IEC 60559:
<ul>
</ul>
<a name="F.7.4" href="#F.7.4"><h4>F.7.4 Constant expressions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An arithmetic constant expression of floating type, other than one in an initializer for an
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'').<sup><a href="#note315"><b>315)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
#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
-<!--page 462 indent 4-->
+<!--page 462 -->
execution time.
</small>
<a name="F.7.5" href="#F.7.5"><h4>F.7.5 Initialization</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
All computation for automatic initialization is done (as if) at execution time; thus, it is
affected by any operative modes and raises floating-point exceptions as required by
IEC 60559 (provided the state for the FENV_ACCESS pragma is ''on''). All computation
for initialization of objects that have static storage duration is done (as if) at translation
time.
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS ON
-<!--page 463 indent 4-->
+<!--page 463 -->
<h6>footnotes</h6>
<p><small><a name="note316" href="#note316">316)</a> Use of float_t and double_t variables increases the likelihood of translation-time computation.
</small>
<a name="F.7.6" href="#F.7.6"><h4>F.7.6 Changing the environment</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Operations defined in <a href="#6.5">6.5</a> and functions and macros defined for the standard libraries
change floating-point status flags and control modes just as indicated by their
specifications (including conformance to IEC 60559). They do not change flags or modes
(so as to be detectable by the user) in any other cases.
-<p><!--para 2-->
+<p><!--para 2 -->
If the argument to the feraiseexcept function in <a href="#7.6"><fenv.h></a> represents IEC 60559
valid coincident floating-point exceptions for atomic operations (namely ''overflow'' and
''inexact'', or ''underflow'' and ''inexact''), then ''overflow'' or ''underflow'' is raised
before ''inexact''.
<a name="F.8" href="#F.8"><h3>F.8 Optimization</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This section identifies code transformations that might subvert IEC 60559-specified
behavior, and others that do not.
<a name="F.8.1" href="#F.8.1"><h4>F.8.1 Global transformations</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Floating-point arithmetic operations and external function calls may entail side effects
which optimization shall honor, at least where the state of the FENV_ACCESS pragma is
''on''. The flags and modes in the floating-point environment may be regarded as global
variables; floating-point operations (+, *, etc.) implicitly read the modes and write the
flags.
-<p><!--para 2-->
+<p><!--para 2 -->
Concern about side effects may inhibit code motion and removal of seemingly useless
code. For example, in
<pre>
body might not execute (maybe 0 >= n), x + 1 cannot be moved out of the loop. (Of
course these optimizations are valid if the implementation can rule out the nettlesome
cases.)
-<p><!--para 3-->
+<p><!--para 3 -->
This specification does not require support for trap handlers that maintain information
about the order or count of floating-point exceptions. Therefore, between function calls,
floating-point exceptions need not be precise: the actual order and number of occurrences
of floating-point exceptions (> 1) may vary from what the source code expresses. Thus,
the preceding loop could be treated as
-<!--page 464 indent 4-->
+<!--page 464 -->
<pre>
if (0 < n) x + 1;</pre>
<a name="F.8.2" href="#F.8.2"><h4>F.8.2 Expression transformations</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
x / 2 <-> x * 0.5 Although similar transformations involving inexact
<pre>
constants generally do not yield numerically equivalent
implementation can replace x - 0 by x, even if x</pre>
-<!--page 465 indent 4-->
+<!--page 465 -->
<pre>
might be zero.</pre>
-x <-> 0 - x The expressions -x and 0 - x are not equivalent if x
</small>
<a name="F.8.3" href="#F.8.3"><h4>F.8.3 Relational operators</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
x != x -> false The statement x != x is true if x is a NaN.
x == x -> true The statement x == x is false if x is a NaN.
x < y -> isless(x,y) (and similarly for <=, >, >=) Though numerically
of the FENV_ACCESS pragma is ''off''.</pre>
The sense of relational operators shall be maintained. This includes handling unordered
cases as expressed by the source code.
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE
<pre>
// calls g and raises ''invalid'' if a and b are unordered
else
f();</pre>
nor, unless the state of the FENV_ACCESS pragma is ''off'', to
-<!--page 466 indent 4-->
+<!--page 466 -->
<pre>
// calls g without raising ''invalid'' if a and b are unordered
if (isless(a,b))
<a name="F.8.4" href="#F.8.4"><h4>F.8.4 Constant arithmetic</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The implementation shall honor floating-point exceptions raised by execution-time
constant arithmetic wherever the state of the FENV_ACCESS pragma is ''on''. (See <a href="#F.7.4">F.7.4</a>
and <a href="#F.7.5">F.7.5</a>.) An operation on constants that raises no floating-point exception can be
</small>
<a name="F.9" href="#F.9"><h3>F.9 Mathematics <math.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This subclause contains specifications of <a href="#7.12"><math.h></a> facilities that are particularly suited
for IEC 60559 implementations.
-<p><!--para 2-->
+<p><!--para 2 -->
The Standard C macro HUGE_VAL and its float and long double analogs,
HUGE_VALF and HUGE_VALL, expand to expressions whose values are positive
infinities.
-<p><!--para 3-->
+<p><!--para 3 -->
Special cases for functions in <a href="#7.12"><math.h></a> are covered directly or indirectly by
IEC 60559. The functions that IEC 60559 specifies directly are identified in <a href="#F.3">F.3</a>. The
other functions in <a href="#7.12"><math.h></a> treat infinities, NaNs, signed zeros, subnormals, and
(provided the state of the FENV_ACCESS pragma is ''on'') the floating-point status flags
in a manner consistent with the basic arithmetic operations covered by IEC 60559.
-<p><!--para 4-->
+<p><!--para 4 -->
The expression math_errhandling & MATH_ERREXCEPT shall evaluate to a
nonzero value.
-<p><!--para 5-->
+<p><!--para 5 -->
The ''invalid'' and ''divide-by-zero'' floating-point exceptions are raised as specified in
subsequent subclauses of this annex.
-<p><!--para 6-->
+<p><!--para 6 -->
The ''overflow'' floating-point exception is raised whenever an infinity -- or, because of
rounding direction, a maximal-magnitude finite number -- is returned in lieu of a value
-<!--page 467 indent 5-->
+<!--page 467 -->
whose magnitude is too large.
-<p><!--para 7-->
+<p><!--para 7 -->
The ''underflow'' floating-point exception is raised whenever a result is tiny (essentially
subnormal or zero) and suffers loss of accuracy.<sup><a href="#note320"><b>320)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
Whether or when library functions raise the ''inexact'' floating-point exception is
unspecified, unless explicitly specified otherwise.
-<p><!--para 9-->
+<p><!--para 9 -->
Whether or when library functions raise an undeserved ''underflow'' floating-point
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.
-<p><!--para 10-->
+<p><!--para 10 -->
Whether the functions honor the rounding direction mode is implementation-defined,
unless explicitly specified otherwise.
-<p><!--para 11-->
+<p><!--para 11 -->
Functions with a NaN argument return a NaN result and raise no floating-point exception,
except where stated otherwise.
-<p><!--para 12-->
+<p><!--para 12 -->
The specifications in the following subclauses append to the definitions in <a href="#7.12"><math.h></a>.
For families of functions, the specifications apply to all of the functions even though only
the principal function is shown. Unless otherwise specified, where the symbol ''(+-)''
occurs in both an argument and the result, the result has the same sign as the argument.
Recommended practice
-<p><!--para 13-->
+<p><!--para 13 -->
If a function with one or more NaN arguments returns a NaN result, the result should be
the same as one of the NaN arguments (after possible type conversion), except perhaps
for the sign.
<a name="F.9.1" href="#F.9.1"><h4>F.9.1 Trigonometric functions</h4></a>
<a name="F.9.1.1" href="#F.9.1.1"><h5>F.9.1.1 The acos functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> acos(1) returns +0.
<li> acos(x) returns a NaN and raises the ''invalid'' floating-point exception for
-<!--page 468 indent 4-->
+<!--page 468 -->
</ul>
<a name="F.9.1.2" href="#F.9.1.2"><h5>F.9.1.2 The asin functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> asin((+-)0) returns (+-)0.
<li> asin(x) returns a NaN and raises the ''invalid'' floating-point exception for
</ul>
<a name="F.9.1.3" href="#F.9.1.3"><h5>F.9.1.3 The atan functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> atan((+-)0) returns (+-)0.
<li> atan((+-)(inf)) returns (+-)pi /2.
</ul>
<a name="F.9.1.4" href="#F.9.1.4"><h5>F.9.1.4 The atan2 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> atan2((+-)0, -0) returns (+-)pi .<sup><a href="#note322"><b>322)</b></a></sup>
<li> atan2((+-)0, +0) returns (+-)0.
</small>
<a name="F.9.1.5" href="#F.9.1.5"><h5>F.9.1.5 The cos functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cos((+-)0) returns 1.
<li> cos((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
</ul>
<a name="F.9.1.6" href="#F.9.1.6"><h5>F.9.1.6 The sin functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> sin((+-)0) returns (+-)0.
<li> sin((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
-<!--page 469 indent 4-->
+<!--page 469 -->
</ul>
<a name="F.9.1.7" href="#F.9.1.7"><h5>F.9.1.7 The tan functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> tan((+-)0) returns (+-)0.
<li> tan((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
<a name="F.9.2" href="#F.9.2"><h4>F.9.2 Hyperbolic functions</h4></a>
<a name="F.9.2.1" href="#F.9.2.1"><h5>F.9.2.1 The acosh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> acosh(1) returns +0.
<li> acosh(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 1.
</ul>
<a name="F.9.2.2" href="#F.9.2.2"><h5>F.9.2.2 The asinh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> asinh((+-)0) returns (+-)0.
<li> asinh((+-)(inf)) returns (+-)(inf).
</ul>
<a name="F.9.2.3" href="#F.9.2.3"><h5>F.9.2.3 The atanh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> atanh((+-)0) returns (+-)0.
<li> atanh((+-)1) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception.
</ul>
<a name="F.9.2.4" href="#F.9.2.4"><h5>F.9.2.4 The cosh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cosh((+-)0) returns 1.
<li> cosh((+-)(inf)) returns +(inf).
</ul>
<a name="F.9.2.5" href="#F.9.2.5"><h5>F.9.2.5 The sinh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> sinh((+-)0) returns (+-)0.
<li> sinh((+-)(inf)) returns (+-)(inf).
</ul>
<a name="F.9.2.6" href="#F.9.2.6"><h5>F.9.2.6 The tanh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> tanh((+-)0) returns (+-)0.
<li> tanh((+-)(inf)) returns (+-)1.
-<!--page 470 indent 4-->
+<!--page 470 -->
</ul>
<a name="F.9.3" href="#F.9.3"><h4>F.9.3 Exponential and logarithmic functions</h4></a>
<a name="F.9.3.1" href="#F.9.3.1"><h5>F.9.3.1 The exp functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> exp((+-)0) returns 1.
<li> exp(-(inf)) returns +0.
</ul>
<a name="F.9.3.2" href="#F.9.3.2"><h5>F.9.3.2 The exp2 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> exp2((+-)0) returns 1.
<li> exp2(-(inf)) returns +0.
</ul>
<a name="F.9.3.3" href="#F.9.3.3"><h5>F.9.3.3 The expm1 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> expm1((+-)0) returns (+-)0.
<li> expm1(-(inf)) returns -1.
</ul>
<a name="F.9.3.4" href="#F.9.3.4"><h5>F.9.3.4 The frexp functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> frexp((+-)0, exp) returns (+-)0, and stores 0 in the object pointed to by exp.
<li> frexp((+-)(inf), exp) returns (+-)(inf), and stores an unspecified value in the object
<li> frexp(NaN, exp) stores an unspecified value in the object pointed to by exp
(and returns a NaN).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
frexp raises no floating-point exceptions.
-<p><!--para 3-->
+<p><!--para 3 -->
On a binary system, the body of the frexp function might be
<pre>
{
}</pre>
<a name="F.9.3.5" href="#F.9.3.5"><h5>F.9.3.5 The ilogb functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
If the correct result is outside the range of the return type, the numeric result is
unspecified and the ''invalid'' floating-point exception is raised.
-<!--page 471 indent 4-->
+<!--page 471 -->
<a name="F.9.3.6" href="#F.9.3.6"><h5>F.9.3.6 The ldexp functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
On a binary system, ldexp(x, exp) is equivalent to scalbn(x, exp).
<a name="F.9.3.7" href="#F.9.3.7"><h5>F.9.3.7 The log functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> log((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> log(1) returns +0.
</ul>
<a name="F.9.3.8" href="#F.9.3.8"><h5>F.9.3.8 The log10 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> log10((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> log10(1) returns +0.
</ul>
<a name="F.9.3.9" href="#F.9.3.9"><h5>F.9.3.9 The log1p functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> log1p((+-)0) returns (+-)0.
<li> log1p(-1) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
</ul>
<a name="F.9.3.10" href="#F.9.3.10"><h5>F.9.3.10 The log2 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> log2((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> log2(1) returns +0.
</ul>
<a name="F.9.3.11" href="#F.9.3.11"><h5>F.9.3.11 The logb functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> logb((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> logb((+-)(inf)) returns +(inf).
-<!--page 472 indent 4-->
+<!--page 472 -->
</ul>
<a name="F.9.3.12" href="#F.9.3.12"><h5>F.9.3.12 The modf functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> modf((+-)x, iptr) returns a result with the same sign as x.
<li> modf((+-)(inf), iptr) returns (+-)0 and stores (+-)(inf) in the object pointed to by iptr.
<li> modf(NaN, iptr) stores a NaN in the object pointed to by iptr (and returns a
NaN).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
modf behaves as though implemented by
<pre>
#include <a href="#7.12"><math.h></a>
}</pre>
<a name="F.9.3.13" href="#F.9.3.13"><h5>F.9.3.13 The scalbn and scalbln functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> scalbn((+-)0, n) returns (+-)0.
<li> scalbn(x, 0) returns x.
<a name="F.9.4" href="#F.9.4"><h4>F.9.4 Power and absolute value functions</h4></a>
<a name="F.9.4.1" href="#F.9.4.1"><h5>F.9.4.1 The cbrt functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cbrt((+-)0) returns (+-)0.
<li> cbrt((+-)(inf)) returns (+-)(inf).
</ul>
<a name="F.9.4.2" href="#F.9.4.2"><h5>F.9.4.2 The fabs functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> fabs((+-)0) returns +0.
<li> fabs((+-)(inf)) returns +(inf).
-<!--page 473 indent 4-->
+<!--page 473 -->
</ul>
<a name="F.9.4.3" href="#F.9.4.3"><h5>F.9.4.3 The hypot functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> hypot(x, y), hypot(y, x), and hypot(x, -y) are equivalent.
<li> hypot(x, (+-)0) is equivalent to fabs(x).
</ul>
<a name="F.9.4.4" href="#F.9.4.4"><h5>F.9.4.4 The pow functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> pow((+-)0, y) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception
for y an odd integer < 0.
<li> pow(-(inf), y) returns +(inf) for y > 0 and not an odd integer.
<li> pow(+(inf), y) returns +0 for y < 0.
<li> pow(+(inf), y) returns +(inf) for y > 0.
-<!--page 474 indent 4-->
+<!--page 474 -->
</ul>
<a name="F.9.4.5" href="#F.9.4.5"><h5>F.9.4.5 The sqrt functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
sqrt is fully specified as a basic arithmetic operation in IEC 60559.
<a name="F.9.5" href="#F.9.5"><h4>F.9.5 Error and gamma functions</h4></a>
<a name="F.9.5.1" href="#F.9.5.1"><h5>F.9.5.1 The erf functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> erf((+-)0) returns (+-)0.
<li> erf((+-)(inf)) returns (+-)1.
</ul>
<a name="F.9.5.2" href="#F.9.5.2"><h5>F.9.5.2 The erfc functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> erfc(-(inf)) returns 2.
<li> erfc(+(inf)) returns +0.
</ul>
<a name="F.9.5.3" href="#F.9.5.3"><h5>F.9.5.3 The lgamma functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> lgamma(1) returns +0.
<li> lgamma(2) returns +0.
</ul>
<a name="F.9.5.4" href="#F.9.5.4"><h5>F.9.5.4 The tgamma functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> tgamma((+-)0) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> tgamma(x) returns a NaN and raises the ''invalid'' floating-point exception for x a
<a name="F.9.6" href="#F.9.6"><h4>F.9.6 Nearest integer functions</h4></a>
<a name="F.9.6.1" href="#F.9.6.1"><h5>F.9.6.1 The ceil functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> ceil((+-)0) returns (+-)0.
<li> ceil((+-)(inf)) returns (+-)(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The double version of ceil behaves as though implemented by
-<!--page 475 indent 4-->
+<!--page 475 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.6"><fenv.h></a>
}</pre>
<a name="F.9.6.2" href="#F.9.6.2"><h5>F.9.6.2 The floor functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> floor((+-)0) returns (+-)0.
<li> floor((+-)(inf)) returns (+-)(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
See the sample implementation for ceil in <a href="#F.9.6.1">F.9.6.1</a>.
<a name="F.9.6.3" href="#F.9.6.3"><h5>F.9.6.3 The nearbyint functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The nearbyint functions use IEC 60559 rounding according to the current rounding
direction. They do not raise the ''inexact'' floating-point exception if the result differs in
value from the argument.
</ul>
<a name="F.9.6.4" href="#F.9.6.4"><h5>F.9.6.4 The rint functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The rint functions differ from the nearbyint functions only in that they do raise the
''inexact'' floating-point exception if the result differs in value from the argument.
<a name="F.9.6.5" href="#F.9.6.5"><h5>F.9.6.5 The lrint and llrint functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The lrint and llrint functions provide floating-to-integer conversion as prescribed
by IEC 60559. They round according to the current rounding direction. If the rounded
value is outside the range of the return type, the numeric result is unspecified and the
''invalid'' floating-point exception is raised. When they raise no other floating-point
exception and the result differs from the argument, they raise the ''inexact'' floating-point
exception.
-<!--page 476 indent 4-->
+<!--page 476 -->
<a name="F.9.6.6" href="#F.9.6.6"><h5>F.9.6.6 The round functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> round((+-)0) returns (+-)0.
<li> round((+-)(inf)) returns (+-)(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The double version of round behaves as though implemented by
<pre>
#include <a href="#7.12"><math.h></a>
exception for non-integer numeric arguments, as this implementation does.
<a name="F.9.6.7" href="#F.9.6.7"><h5>F.9.6.7 The lround and llround functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The lround and llround functions differ from the lrint and llrint functions
with the default rounding direction just in that the lround and llround functions
round halfway cases away from zero and need not raise the ''inexact'' floating-point
exception for non-integer arguments that round to within the range of the return type.
<a name="F.9.6.8" href="#F.9.6.8"><h5>F.9.6.8 The trunc functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The trunc functions use IEC 60559 rounding toward zero (regardless of the current
rounding direction).
<ul>
<li> trunc((+-)0) returns (+-)0.
<li> trunc((+-)(inf)) returns (+-)(inf).
-<!--page 477 indent 4-->
+<!--page 477 -->
</ul>
<a name="F.9.7" href="#F.9.7"><h4>F.9.7 Remainder functions</h4></a>
<a name="F.9.7.1" href="#F.9.7.1"><h5>F.9.7.1 The fmod functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> fmod((+-)0, y) returns (+-)0 for y not zero.
<li> fmod(x, y) returns a NaN and raises the ''invalid'' floating-point exception for x
infinite or y zero.
<li> fmod(x, (+-)(inf)) returns x for x not infinite.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The double version of fmod behaves as though implemented by
<pre>
#include <a href="#7.12"><math.h></a>
}</pre>
<a name="F.9.7.2" href="#F.9.7.2"><h5>F.9.7.2 The remainder functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The remainder functions are fully specified as a basic arithmetic operation in
IEC 60559.
<a name="F.9.7.3" href="#F.9.7.3"><h5>F.9.7.3 The remquo functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The remquo functions follow the specifications for the remainder functions. They
have no further specifications special to IEC 60559 implementations.
<a name="F.9.8" href="#F.9.8"><h4>F.9.8 Manipulation functions</h4></a>
<a name="F.9.8.1" href="#F.9.8.1"><h5>F.9.8.1 The copysign functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
copysign is specified in the Appendix to IEC 60559.
<a name="F.9.8.2" href="#F.9.8.2"><h5>F.9.8.2 The nan functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
All IEC 60559 implementations support quiet NaNs, in all floating formats.
-<!--page 478 indent 4-->
+<!--page 478 -->
<a name="F.9.8.3" href="#F.9.8.3"><h5>F.9.8.3 The nextafter functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> nextafter(x, y) raises the ''overflow'' and ''inexact'' floating-point exceptions
for x finite and the function value infinite.
</ul>
<a name="F.9.8.4" href="#F.9.8.4"><h5>F.9.8.4 The nexttoward functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
No additional requirements beyond those on nextafter.
<a name="F.9.9" href="#F.9.9"><h4>F.9.9 Maximum, minimum, and positive difference functions</h4></a>
<a name="F.9.9.1" href="#F.9.9.1"><h5>F.9.9.1 The fdim functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
No additional requirements.
<a name="F.9.9.2" href="#F.9.9.2"><h5>F.9.9.2 The fmax functions</h5></a>
-<p><!--para 1-->
+<p><!--para 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).
-<p><!--para 2-->
+<p><!--para 2 -->
The body of the fmax function might be<sup><a href="#note323"><b>323)</b></a></sup>
<pre>
{ return (isgreaterequal(x, y) ||
</small>
<a name="F.9.9.3" href="#F.9.9.3"><h5>F.9.9.3 The fmin functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The fmin functions are analogous to the fmax functions (see <a href="#F.9.9.2">F.9.9.2</a>).
<a name="F.9.10" href="#F.9.10"><h4>F.9.10 Floating multiply-add</h4></a>
<a name="F.9.10.1" href="#F.9.10.1"><h5>F.9.10.1 The fma functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> fma(x, y, z) computes xy + z, correctly rounded once.
<li> fma(x, y, z) returns a NaN and optionally raises the ''invalid'' floating-point
-<!--page 479 indent 4-->
+<!--page 479 -->
</ul>
<a name="G" href="#G"><h2>Annex G</h2></a>
IEC 60559-compatible complex arithmetic</pre>
<a name="G.1" href="#G.1"><h3>G.1 Introduction</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This annex supplements <a href="#F">annex F</a> to specify complex arithmetic for compatibility with
IEC 60559 real floating-point arithmetic. Although these specifications have been
carefully designed, there is little existing practice to validate the design decisions.
__STDC_IEC_559_COMPLEX__ should conform to the specifications in this annex.
<a name="G.2" href="#G.2"><h3>G.2 Types</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
There is a new keyword _Imaginary, which is used to specify imaginary types. It is
used as a type specifier within declaration specifiers in the same way as _Complex is
(thus, _Imaginary float is a valid type name).
-<p><!--para 2-->
+<p><!--para 2 -->
There are three imaginary types, designated as float _Imaginary, double
_Imaginary, and long double _Imaginary. The imaginary types (along with
the real floating and complex types) are floating types.
-<p><!--para 3-->
+<p><!--para 3 -->
For imaginary types, the corresponding real type is given by deleting the keyword
_Imaginary from the type name.
-<p><!--para 4-->
+<p><!--para 4 -->
Each imaginary type has the same representation and alignment requirements as the
corresponding real type. The value of an object of imaginary type is the value of the real
representation times the imaginary unit.
-<p><!--para 5-->
+<p><!--para 5 -->
The imaginary type domain comprises the imaginary types.
<a name="G.3" href="#G.3"><h3>G.3 Conventions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A complex or imaginary value with at least one infinite part is regarded as an infinity
(even if its other part is a NaN). A complex or imaginary value is a finite number if each
of its parts is a finite number (neither infinite nor NaN). A complex or imaginary value is
a zero if each of its parts is a zero.
-<!--page 480 indent 4-->
+<!--page 480 -->
<a name="G.4" href="#G.4"><h3>G.4 Conversions</h3></a>
<a name="G.4.1" href="#G.4.1"><h4>G.4.1 Imaginary types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Conversions among imaginary types follow rules analogous to those for real floating
types.
<a name="G.4.2" href="#G.4.2"><h4>G.4.2 Real and imaginary</h4></a>
-<p><!--para 1-->
+<p><!--para 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.
-<p><!--para 2-->
+<p><!--para 2 -->
When a value of real type is converted to an imaginary type, the result is a positive
imaginary zero.
</small>
<a name="G.4.3" href="#G.4.3"><h4>G.4.3 Imaginary and complex</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value of imaginary type is converted to a complex type, the real part of the
complex result value is a positive zero and the imaginary part of the complex result value
is determined by the conversion rules for the corresponding real types.
-<p><!--para 2-->
+<p><!--para 2 -->
When a value of complex type is converted to an imaginary type, the real part of the
complex value is discarded and the value of the imaginary part is converted according to
the conversion rules for the corresponding real types.
<a name="G.5" href="#G.5"><h3>G.5 Binary operators</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following subclauses supplement <a href="#6.5">6.5</a> in order to specify the type of the result for an
operation with an imaginary operand.
-<p><!--para 2-->
+<p><!--para 2 -->
For most operand types, the value of the result of a binary operator with an imaginary or
complex operand is completely determined, with reference to real arithmetic, by the usual
mathematical formula. For some operand types, the usual mathematical formula is
-<!--page 481 indent 4-->
+<!--page 481 -->
<a name="G.5.1" href="#G.5.1"><h4>G.5.1 Multiplicative operators</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
If one operand has real type and the other operand has imaginary type, then the result has
imaginary type. If both operands have imaginary type, then the result has real type. (If
either operand has complex type, then the result has complex type.)
-<p><!--para 2-->
+<p><!--para 2 -->
If the operands are not both complex, then the result and floating-point exception
behavior of the * operator is defined by the usual mathematical formula:
<pre>
<pre>
iy i(yu) -yv (-yv) + i(yu)</pre>
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
x + iy (xu) + i(yu) (-yv) + i(xv)</pre>
If the second operand is not complex, then the result and floating-point exception
<pre>
iy i(y/u) y/v</pre>
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
x + iy (x/u) + i(y/u) (y/v) + i(-x/v)</pre>
The * and / operators satisfy the following infinity properties for all real, imaginary, and
-<!--page 482 indent 4-->
+<!--page 482 -->
<li> if the first operand is a nonzero finite number or an infinity and the second operand is
a zero, then the result of the / operator is an infinity.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
If both operands of the * operator are complex or if the second operand of the / operator
is complex, the operator raises floating-point exceptions if appropriate for the calculation
of the parts of the result, and may raise spurious floating-point exceptions.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 1 Multiplication of double _Complex operands could be implemented as follows. Note
that the imaginary unit I has imaginary type (see <a href="#G.6">G.6</a>).
-<!--page 483 indent 4-->
-<p><!--para 7-->
+<!--page 483 -->
+<p><!--para 7 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.3"><complex.h></a>
This implementation achieves the required treatment of infinities at the cost of only one isnan test in
ordinary (finite) cases. It is less than ideal in that undue overflow and underflow may occur.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 2 Division of two double _Complex operands could be implemented as follows.
-<!--page 484 indent 4-->
-<p><!--para 9-->
+<!--page 484 -->
+<p><!--para 9 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.3"><complex.h></a>
<a name="G.5.2" href="#G.5.2"><h4>G.5.2 Additive operators</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
If both operands have imaginary type, then the result has imaginary type. (If one operand
has real type and the other operand has imaginary type, or if either operand has complex
type, then the result has complex type.)
-<p><!--para 2-->
+<p><!--para 2 -->
In all cases the result and floating-point exception behavior of a + or - operator is defined
by the usual mathematical formula:
<pre>
x + iy (x (+-) u) + iy x + i(y (+-) v) (x (+-) u) + i(y (+-) v)</pre>
<a name="G.6" href="#G.6"><h3>G.6 Complex arithmetic <complex.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The macros
<pre>
imaginary</pre>
is defined to be _Imaginary_I (not _Complex_I as stated in <a href="#7.3">7.3</a>). Notwithstanding
the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and then perhaps redefine the macro
imaginary.
-<p><!--para 2-->
+<p><!--para 2 -->
This subclause contains specifications for the <a href="#7.3"><complex.h></a> functions that are
particularly suited to IEC 60559 implementations. For families of functions, the
specifications apply to all of the functions even though only the principal function is
-<!--page 485 indent 4-->
+<!--page 485 -->
shown. Unless otherwise specified, where the symbol ''(+-)'' occurs in both an argument
and the result, the result has the same sign as the argument.
-<p><!--para 3-->
+<p><!--para 3 -->
The functions are continuous onto both sides of their branch cuts, taking into account the
sign of zero. For example, csqrt(-2 (+-) i0) = (+-)i(sqrt)2. ???
-<p><!--para 4-->
+<p><!--para 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.<sup><a href="#note326"><b>326)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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.
-<p><!--para 6-->
+<p><!--para 6 -->
Each of the functions cabs and carg is specified by a formula in terms of a real
function (whose special cases are covered in <a href="#F">annex F</a>):
-<p><!--para 7-->
+<p><!--para 7 -->
<pre>
cabs(x + iy) = hypot(x, y)
carg(x + iy) = atan2(y, x)</pre>
Each of the functions casin, catan, ccos, csin, and ctan is specified implicitly by
a formula in terms of other complex functions (whose special cases are specified below):
-<p><!--para 8-->
+<p><!--para 8 -->
<pre>
casin(z) = -i casinh(iz)
catan(z) = -i catanh(iz)
specifications for the upper half-plane imply the specifications for the lower half-plane; if
the function f is also either even, f (-z) = f (z), or odd, f (-z) = - f (z), then the
specifications for the first quadrant imply the specifications for the other three quadrants.
-<p><!--para 9-->
+<p><!--para 9 -->
In the following subclauses, cis(y) is defined as cos(y) + i sin(y).
-<!--page 486 indent 4-->
+<!--page 486 -->
<h6>footnotes</h6>
<p><small><a name="note326" href="#note326">326)</a> As noted in <a href="#G.3">G.3</a>, a complex value with at least one infinite part is regarded as an infinity even if its
<a name="G.6.1" href="#G.6.1"><h4>G.6.1 Trigonometric functions</h4></a>
<a name="G.6.1.1" href="#G.6.1.1"><h5>G.6.1.1 The cacos functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cacos(conj(z)) = conj(cacos(z)).
<li> cacos((+-)0 + i0) returns pi /2 - i0.
<a name="G.6.2" href="#G.6.2"><h4>G.6.2 Hyperbolic functions</h4></a>
<a name="G.6.2.1" href="#G.6.2.1"><h5>G.6.2.1 The cacosh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cacosh(conj(z)) = conj(cacosh(z)).
<li> cacosh((+-)0 + i0) returns +0 + ipi /2.
<li> cacosh(-(inf) + i (inf)) returns +(inf) + i3pi /4.
<li> cacosh(+(inf) + i (inf)) returns +(inf) + ipi /4.
<li> cacosh((+-)(inf) + iNaN) returns +(inf) + iNaN.
-<!--page 487 indent 4-->
+<!--page 487 -->
<li> cacosh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid''
floating-point exception, for finite y.
<li> cacosh(NaN + i (inf)) returns +(inf) + iNaN.
</ul>
<a name="G.6.2.2" href="#G.6.2.2"><h5>G.6.2.2 The casinh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> casinh(conj(z)) = conj(casinh(z)) and casinh is odd.
<li> casinh(+0 + i0) returns 0 + i0.
</ul>
<a name="G.6.2.3" href="#G.6.2.3"><h5>G.6.2.3 The catanh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> catanh(conj(z)) = conj(catanh(z)) and catanh is odd.
<li> catanh(+0 + i0) returns +0 + i0.
<li> catanh(+(inf) + iy) returns +0 + ipi /2, for finite positive-signed y.
<li> catanh(+(inf) + i (inf)) returns +0 + ipi /2.
<li> catanh(+(inf) + iNaN) returns +0 + iNaN.
-<!--page 488 indent 4-->
+<!--page 488 -->
<li> catanh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid''
floating-point exception, for finite y.
<li> catanh(NaN + i (inf)) returns (+-)0 + ipi /2 (where the sign of the real part of the result is
</ul>
<a name="G.6.2.4" href="#G.6.2.4"><h5>G.6.2.4 The ccosh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> ccosh(conj(z)) = conj(ccosh(z)) and ccosh is even.
<li> ccosh(+0 + i0) returns 1 + i0.
</ul>
<a name="G.6.2.5" href="#G.6.2.5"><h5>G.6.2.5 The csinh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> csinh(conj(z)) = conj(csinh(z)) and csinh is odd.
<li> csinh(+0 + i0) returns +0 + i0.
unspecified) and raises the ''invalid'' floating-point exception.
<li> csinh(+0 + iNaN) returns (+-)0 + iNaN (where the sign of the real part of the result is
unspecified).
-<!--page 489 indent 4-->
+<!--page 489 -->
<li> csinh(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point
exception, for positive finite x.
<li> csinh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
</ul>
<a name="G.6.2.6" href="#G.6.2.6"><h5>G.6.2.6 The ctanh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> ctanh(conj(z)) = conj(ctanh(z))and ctanh is odd.
<li> ctanh(+0 + i0) returns +0 + i0.
<li> ctanh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
point exception, for all nonzero numbers y.
<li> ctanh(NaN + iNaN) returns NaN + iNaN.
-<!--page 490 indent 4-->
+<!--page 490 -->
</ul>
<a name="G.6.3" href="#G.6.3"><h4>G.6.3 Exponential and logarithmic functions</h4></a>
<a name="G.6.3.1" href="#G.6.3.1"><h5>G.6.3.1 The cexp functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cexp(conj(z)) = conj(cexp(z)).
<li> cexp((+-)0 + i0) returns 1 + i0.
</ul>
<a name="G.6.3.2" href="#G.6.3.2"><h5>G.6.3.2 The clog functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> clog(conj(z)) = conj(clog(z)).
<li> clog(-0 + i0) returns -(inf) + ipi and raises the ''divide-by-zero'' floating-point
<li> clog(x + i (inf)) returns +(inf) + ipi /2, for finite x.
<li> clog(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
point exception, for finite x.
-<!--page 491 indent 4-->
+<!--page 491 -->
<li> clog(-(inf) + iy) returns +(inf) + ipi , for finite positive-signed y.
<li> clog(+(inf) + iy) returns +(inf) + i0, for finite positive-signed y.
<li> clog(-(inf) + i (inf)) returns +(inf) + i3pi /4.
<a name="G.6.4" href="#G.6.4"><h4>G.6.4 Power and absolute-value functions</h4></a>
<a name="G.6.4.1" href="#G.6.4.1"><h5>G.6.4.1 The cpow functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The cpow functions raise floating-point exceptions if appropriate for the calculation of
the parts of the result, and may raise spurious exceptions.<sup><a href="#note327"><b>327)</b></a></sup>
</small>
<a name="G.6.4.2" href="#G.6.4.2"><h5>G.6.4.2 The csqrt functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> csqrt(conj(z)) = conj(csqrt(z)).
<li> csqrt((+-)0 + i0) returns +0 + i0.
-<!--page 492 indent 4-->
+<!--page 492 -->
</ul>
<a name="G.7" href="#G.7"><h3>G.7 Type-generic math <tgmath.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Type-generic macros that accept complex arguments also accept imaginary arguments. If
an argument is imaginary, the macro expands to an expression whose type is real,
imaginary, or complex, as appropriate for the particular function: if the argument is
imaginary, then the types of cos, cosh, fabs, carg, cimag, and creal are real; the
types of sin, tan, sinh, tanh, asin, atan, asinh, and atanh are imaginary; and
the types of the others are complex.
-<p><!--para 2-->
+<p><!--para 2 -->
Given an imaginary argument, each of the type-generic macros cos, sin, tan, cosh,
sinh, tanh, asin, atan, asinh, atanh is specified by a formula in terms of real
functions:
-<!--page 493 indent 4-->
+<!--page 493 -->
<pre>
cos(iy) = cosh(y)
sin(iy) = i sinh(y)
Language independent arithmetic</pre>
<a name="H.1" href="#H.1"><h3>H.1 Introduction</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This annex documents the extent to which the C language supports the ISO/IEC 10967-1
standard for language-independent arithmetic (LIA-1). LIA-1 is more general than
IEC 60559 (<a href="#F">annex F</a>) in that it covers integer and diverse floating-point arithmetics.
<a name="H.2" href="#H.2"><h3>H.2 Types</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The relevant C arithmetic types meet the requirements of LIA-1 types if an
implementation adds notification of exceptional arithmetic operations and meets the 1
unit in the last place (ULP) accuracy requirement (LIA-1 subclause <a href="#5.2.8">5.2.8</a>).
<a name="H.2.1" href="#H.2.1"><h4>H.2.1 Boolean type</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The LIA-1 data type Boolean is implemented by the C data type bool with values of
true and false, all from <a href="#7.16"><stdbool.h></a>.
<a name="H.2.2" href="#H.2.2"><h4>H.2.2 Integer types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The signed C integer types int, long int, long long int, and the corresponding
unsigned types are compatible with LIA-1. If an implementation adds support for the
LIA-1 exceptional values ''integer_overflow'' and ''undefined'', then those types are
in that overflows or out-of-bounds results silently wrap. An implementation that defines
signed integer types as also being modulo need not detect integer overflow, in which case,
only integer divide-by-zero need be detected.
-<p><!--para 2-->
+<p><!--para 2 -->
The parameters for the integer data types can be accessed by the following:
maxint INT_MAX, LONG_MAX, LLONG_MAX, UINT_MAX, ULONG_MAX,
<pre>
ULLONG_MAX</pre>
minint INT_MIN, LONG_MIN, LLONG_MIN
-<p><!--para 3-->
+<p><!--para 3 -->
The parameter ''bounded'' is always true, and is not provided. The parameter ''minint''
is always 0 for the unsigned types, and is not provided for those types.
-<!--page 494 indent 4-->
+<!--page 494 -->
<a name="H.2.2.1" href="#H.2.2.1"><h5>H.2.2.1 Integer operations</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The integer operations on integer types are the following:
addI x + y
subI x - y
where x and y are expressions of the same integer type.
<a name="H.2.3" href="#H.2.3"><h4>H.2.3 Floating-point types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The C floating-point types float, double, and long double are compatible with
LIA-1. If an implementation adds support for the LIA-1 exceptional values
''underflow'', ''floating_overflow'', and ''"undefined'', then those types are conformant
conformant types.
<a name="H.2.3.1" href="#H.2.3.1"><h5>H.2.3.1 Floating-point parameters</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The parameters for a floating point data type can be accessed by the following:
r FLT_RADIX
p FLT_MANT_DIG, DBL_MANT_DIG, LDBL_MANT_DIG
emax FLT_MAX_EXP, DBL_MAX_EXP, LDBL_MAX_EXP
emin FLT_MIN_EXP, DBL_MIN_EXP, LDBL_MIN_EXP
-<p><!--para 2-->
+<p><!--para 2 -->
The derived constants for the floating point types are accessed by the following:
-<!--page 495 indent 4-->
+<!--page 495 -->
fmax FLT_MAX, DBL_MAX, LDBL_MAX
fminN FLT_MIN, DBL_MIN, LDBL_MIN
epsilon FLT_EPSILON, DBL_EPSILON, LDBL_EPSILON
rnd_style FLT_ROUNDS
<a name="H.2.3.2" href="#H.2.3.2"><h5>H.2.3.2 Floating-point operations</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The floating-point operations on floating-point types are the following:
addF x + y
subF x - y
is of type long int.
<a name="H.2.3.3" href="#H.2.3.3"><h5>H.2.3.3 Rounding styles</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The C Standard requires all floating types to use the same radix and rounding style, so
that only one identifier for each is provided to map to LIA-1.
-<p><!--para 2-->
+<p><!--para 2 -->
The FLT_ROUNDS parameter can be used to indicate the LIA-1 rounding styles:
truncate FLT_ROUNDS == 0
-<!--page 496 indent 4-->
+<!--page 496 -->
nearest FLT_ROUNDS == 1
other FLT_ROUNDS != 0 && FLT_ROUNDS != 1
provided that an implementation extends FLT_ROUNDS to cover the rounding style used
in all relevant LIA-1 operations, not just addition as in C.
<a name="H.2.4" href="#H.2.4"><h4>H.2.4 Type conversions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The LIA-1 type conversions are the following type casts:
cvtI' -> I (int)i, (long int)i, (long long int)i,
<pre>
(unsigned long long int)x</pre>
cvtI -> F (float)i, (double)i, (long double)i
cvtF' -> F (float)x, (double)x, (long double)x
-<p><!--para 2-->
+<p><!--para 2 -->
In the above conversions from floating to integer, the use of (cast)x can be replaced with
(cast)round(x), (cast)rint(x), (cast)nearbyint(x), (cast)trunc(x),
(cast)ceil(x), or (cast)floor(x). In addition, C's floating-point to integer
conversion functions, lrint(), llrint(), lround(), and llround(), can be
used. They all meet LIA-1's requirements on floating to integer rounding for in-range
values. For out-of-range values, the conversions shall silently wrap for the modulo types.
-<p><!--para 3-->
+<p><!--para 3 -->
The fmod() function is useful for doing silent wrapping to unsigned integer types, e.g.,
fmod( fabs(rint(x)), 65536.0 ) or (0.0 <= (y = fmod( rint(x),
65536.0 )) ? y : 65536.0 + y) will compute an integer value in the range 0.0
e.g., remainder( rint(x), 65536.0 ) will compute an integer value in the
range -32767.0 to +32768.0 which is not, in general, in the range of signed short
int.
-<p><!--para 4-->
+<p><!--para 4 -->
C's conversions (casts) from floating-point to floating-point can meet LIA-1
requirements if an implementation uses round-to-nearest (IEC 60559 default).
-<p><!--para 5-->
+<p><!--para 5 -->
C's conversions (casts) from integer to floating-point can meet LIA-1 requirements if an
implementation uses round-to-nearest.
-<!--page 497 indent 4-->
+<!--page 497 -->
<a name="H.3" href="#H.3"><h3>H.3 Notification</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Notification is the process by which a user or program is informed that an exceptional
arithmetic operation has occurred. C's operations are compatible with LIA-1 in that C
allows an implementation to cause a notification to occur when any arithmetic operation
returns an exceptional value as defined in LIA-1 clause 5.
<a name="H.3.1" href="#H.3.1"><h4>H.3.1 Notification alternatives</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
LIA-1 requires at least the following two alternatives for handling of notifications:
setting indicators or trap-and-terminate. LIA-1 allows a third alternative: trap-and-
resume.
-<p><!--para 2-->
+<p><!--para 2 -->
An implementation need only support a given notification alternative for the entire
program. An implementation may support the ability to switch between notification
alternatives during execution, but is not required to do so. An implementation can
provide separate selection for each kind of notification, but this is not required.
-<p><!--para 3-->
+<p><!--para 3 -->
C allows an implementation to provide notification. C's SIGFPE (for traps) and
FE_INVALID, FE_DIVBYZERO, FE_OVERFLOW, FE_UNDERFLOW (for indicators)
can provide LIA-1 notification.
-<p><!--para 4-->
+<p><!--para 4 -->
C's signal handlers are compatible with LIA-1. Default handling of SIGFPE can
provide trap-and-terminate behavior, except for those LIA-1 operations implemented by
math library function calls. User-provided signal handlers for SIGFPE allow for trap-
and-resume behavior with the same constraint.
<a name="H.3.1.1" href="#H.3.1.1"><h5>H.3.1.1 Indicators</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
C's <a href="#7.6"><fenv.h></a> status flags are compatible with the LIA-1 indicators.
-<p><!--para 2-->
+<p><!--para 2 -->
The following mapping is for floating-point types:
undefined FE_INVALID, FE_DIVBYZERO
floating_overflow FE_OVERFLOW
underflow FE_UNDERFLOW
-<p><!--para 3-->
+<p><!--para 3 -->
The floating-point indicator interrogation and manipulation operations are:
set_indicators feraiseexcept(i)
clear_indicators feclearexcept(i)
test_indicators fetestexcept(i)
current_indicators fetestexcept(FE_ALL_EXCEPT)
where i is an expression of type int representing a subset of the LIA-1 indicators.
-<p><!--para 4-->
+<p><!--para 4 -->
C allows an implementation to provide the following LIA-1 required behavior: at
program termination if any indicator is set the implementation shall send an unambiguous
-<!--page 498 indent 4-->
+<!--page 498 -->
and ''hard to ignore'' message (see LIA-1 subclause <a href="#6.1.2">6.1.2</a>)
-<p><!--para 5-->
+<p><!--para 5 -->
LIA-1 does not make the distinction between floating-point and integer for ''undefined''.
This documentation makes that distinction because <a href="#7.6"><fenv.h></a> covers only the floating-
point indicators.
<a name="H.3.1.2" href="#H.3.1.2"><h5>H.3.1.2 Traps</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
C is compatible with LIA-1's trap requirements for arithmetic operations, but not for
math library functions (which are not permitted to generate any externally visible
exceptional conditions). An implementation can provide an alternative of notification
through termination with a ''hard-to-ignore'' message (see LIA-1 subclause <a href="#6.1.3">6.1.3</a>).
-<p><!--para 2-->
+<p><!--para 2 -->
LIA-1 does not require that traps be precise.
-<p><!--para 3-->
+<p><!--para 3 -->
C does require that SIGFPE be the signal corresponding to arithmetic exceptions, if there
is any signal raised for them.
-<p><!--para 4-->
+<p><!--para 4 -->
C supports signal handlers for SIGFPE and allows trapping of arithmetic exceptions.
When arithmetic exceptions do trap, C's signal-handler mechanism allows trap-and-
terminate (either default implementation behavior or user replacement for it) or trap-and-
resume, at the programmer's option.
-<!--page 499 indent 4-->
+<!--page 499 -->
<a name="I" href="#I"><h2>Annex I</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Common warnings</pre>
An implementation may generate warnings in many situations, none of which are
specified as part of this International Standard. The following are a few of the more
common situations.
-<p><!--para 2-->
+<p><!--para 2 -->
<ul>
<li> A new struct or union type appears in a function prototype (<a href="#6.2.1">6.2.1</a>, <a href="#6.7.2.3">6.7.2.3</a>).
<li> A block with initialization of an object that has automatic storage duration is jumped
<li> A statement with no apparent effect is encountered (<a href="#6.8">6.8</a>).
<li> A constant expression is used as the controlling expression of a selection statement
(<a href="#6.8.4">6.8.4</a>).
-<!--page 500 indent 0-->
+<!--page 500 -->
<li> An incorrectly formed preprocessing group is encountered while skipping a
preprocessing group (<a href="#6.10.1">6.10.1</a>).
<li> An unrecognized #pragma directive is encountered (<a href="#6.10.6">6.10.6</a>).
-<!--page 501 indent 4-->
+<!--page 501 -->
</ul>
<a name="J" href="#J"><h2>Annex J</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Portability issues</pre>
Standard.
<a name="J.1" href="#J.1"><h3>J.1 Unspecified behavior</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following are unspecified:
<ul>
<li> The manner and timing of static initialization (<a href="#5.1.2">5.1.2</a>).
<li> The order in which subexpressions are evaluated and the order in which side effects
take place, except as specified for the function-call (), &&, ||, ?:, and comma
operators (<a href="#6.5">6.5</a>).
-<!--page 502 indent 0-->
+<!--page 502 -->
<li> The order in which the function designator, arguments, and subexpressions within the
arguments are evaluated in a function call (<a href="#6.5.2.2">6.5.2.2</a>).
<li> The order of side effects among compound literal initialization list expressions
<li> The numeric result of the ilogb functions when the correct value is outside the
range of the return type (<a href="#7.12.6.5">7.12.6.5</a>, <a href="#F.9.3.5">F.9.3.5</a>).
<li> The result of rounding when the value is out of range (<a href="#7.12.9.5">7.12.9.5</a>, <a href="#7.12.9.7">7.12.9.7</a>, <a href="#F.9.6.5">F.9.6.5</a>).
-<!--page 503 indent 0-->
+<!--page 503 -->
<li> The value stored by the remquo functions in the object pointed to by quo when y is
zero (<a href="#7.12.10.3">7.12.10.3</a>).
<li> Whether setjmp is a macro or an identifier with external linkage (<a href="#7.13">7.13</a>).
IEC 60559 floating to integer conversion (<a href="#F.4">F.4</a>).
<li> Whether conversion of non-integer IEC 60559 floating values to integer raises the
''inexact'' floating-point exception (<a href="#F.4">F.4</a>).
-<!--page 504 indent 4-->
+<!--page 504 -->
<li> Whether or when library functions in <a href="#7.12"><math.h></a> raise the ''inexact'' floating-point
exception in an IEC 60559 conformant implementation (<a href="#F.9">F.9</a>).
<li> Whether or when library functions in <a href="#7.12"><math.h></a> raise an undeserved ''underflow''
</ul>
<a name="J.2" href="#J.2"><h3>J.2 Undefined behavior</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior is undefined in the following circumstances:
<ul>
<li> A ''shall'' or ''shall not'' requirement that appears outside of a constraint is violated
indeterminate (<a href="#6.2.4">6.2.4</a>, <a href="#6.7.8">6.7.8</a>, <a href="#6.8">6.8</a>).
<li> A trap representation is read by an lvalue expression that does not have character type
(<a href="#6.2.6.1">6.2.6.1</a>).
-<!--page 505 indent 0-->
+<!--page 505 -->
<li> A trap representation is produced by a side effect that modifies any part of the object
using an lvalue expression that does not have character type (<a href="#6.2.6.1">6.2.6.1</a>).
<li> The arguments to certain operators are such that could produce a negative zero result,
(<a href="#6.4.2.1">6.4.2.1</a>).
<li> Two identifiers differ only in nonsignificant characters (<a href="#6.4.2.1">6.4.2.1</a>).
<li> The identifier __func__ is explicitly declared (<a href="#6.4.2.2">6.4.2.2</a>).
-<!--page 506 indent 0-->
+<!--page 506 -->
<li> The program attempts to modify a string literal (<a href="#6.4.5">6.4.5</a>).
<li> The characters ', \, ", //, or /* occur in the sequence between the < and >
delimiters, or the characters ', \, //, or /* occur in the sequence between the "
the operand of a unary * operator that is evaluated (<a href="#6.5.6">6.5.6</a>).
<li> Pointers that do not point into, or just beyond, the same array object are subtracted
(<a href="#6.5.6">6.5.6</a>).
-<!--page 507 indent 0-->
+<!--page 507 -->
<li> An array subscript is out of range, even if an object is apparently accessible with the
given subscript (as in the lvalue expression a[1][7] given the declaration int
a[4][5]) (<a href="#6.5.6">6.5.6</a>).
<li> A function is declared at block scope with an explicit storage-class specifier other
than extern (<a href="#6.7.1">6.7.1</a>).
<li> A structure or union is defined as containing no named members (<a href="#6.7.2.1">6.7.2.1</a>).
-<!--page 508 indent 0-->
+<!--page 508 -->
<li> An attempt is made to access, or generate a pointer to just past, a flexible array
member of a structure when the referenced object provides no elements for that array
(<a href="#6.7.2.1">6.7.2.1</a>).
compatible return types, or their parameters disagree in use of the ellipsis terminator
or the number and type of parameters (after default argument promotion, when there
is no parameter type list or when one type is specified by a function definition with an
-<!--page 509 indent 0-->
+<!--page 509 -->
identifier list) (<a href="#6.7.5.3">6.7.5.3</a>).
<li> The value of an unnamed member of a structure or union is used (<a href="#6.7.8">6.7.8</a>).
<li> The initializer for a scalar is neither a single expression nor a single expression
(<a href="#6.10.3.2">6.10.3.2</a>).
<li> The result of the preprocessing operator ## is not a valid preprocessing token
(<a href="#6.10.3.3">6.10.3.3</a>).
-<!--page 510 indent 0-->
+<!--page 510 -->
<li> The #line preprocessing directive that results after expansion does not match one of
the two well-defined forms, or its digit sequence specifies zero or a number greater
than 2147483647 (<a href="#6.10.4">6.10.4</a>).
<li> The argument to the assert macro does not have a scalar type (<a href="#7.2">7.2</a>).
<li> The CX_LIMITED_RANGE, FENV_ACCESS, or FP_CONTRACT pragma is used in
any context other than outside all external declarations or preceding all explicit
-<!--page 511 indent 0-->
+<!--page 511 -->
declarations and statements inside a compound statement (<a href="#7.3.4">7.3.4</a>, <a href="#7.6.1">7.6.1</a>, <a href="#7.12.2">7.12.2</a>).
<li> The value of an argument to a character handling function is neither equal to the value
of EOF nor representable as an unsigned char (<a href="#7.4">7.4</a>).
storage class with non-volatile-qualified type, local to the function containing the
invocation of the corresponding setjmp macro, that was changed between the
setjmp invocation and longjmp call (<a href="#7.13.2.1">7.13.2.1</a>).
-<!--page 512 indent 0-->
+<!--page 512 -->
<li> The program specifies an invalid pointer to a signal handler function (<a href="#7.14.1.1">7.14.1.1</a>).
<li> A signal handler returns when the signal corresponded to a computational exception
(<a href="#7.14.1.1">7.14.1.1</a>).
<li> The parameter parmN of a va_start macro is declared with the register
storage class, with a function or array type, or with a type that is not compatible with
the type that results after application of the default argument promotions (<a href="#7.15.1.4">7.15.1.4</a>).
-<!--page 513 indent 0-->
+<!--page 513 -->
<li> The member designator parameter of an offsetof macro is an invalid right
operand of the . operator for the type parameter, or designates a bit-field (<a href="#7.17">7.17</a>).
<li> The argument in an instance of one of the integer-constant macros is not a decimal,
provided (<a href="#7.19.6.1">7.19.6.1</a>, <a href="#7.24.2.1">7.24.2.1</a>).
<li> A conversion specification for a formatted output function uses a # or 0 flag with a
conversion specifier other than those described (<a href="#7.19.6.1">7.19.6.1</a>, <a href="#7.24.2.1">7.24.2.1</a>).
-<!--page 514 indent 0-->
+<!--page 514 -->
<li> A conversion specification for one of the formatted input/output functions uses a
length modifier with a conversion specifier other than those described (<a href="#7.19.6.1">7.19.6.1</a>,
<a href="#7.19.6.2">7.19.6.2</a>, <a href="#7.24.2.1">7.24.2.1</a>, <a href="#7.24.2.2">7.24.2.2</a>).
<a href="#7.24.2.5">7.24.2.5</a>, <a href="#7.24.2.6">7.24.2.6</a>, <a href="#7.24.2.7">7.24.2.7</a>, <a href="#7.24.2.8">7.24.2.8</a>, <a href="#7.24.2.9">7.24.2.9</a>, <a href="#7.24.2.10">7.24.2.10</a>).
<li> The contents of the array supplied in a call to the fgets, gets, or fgetws function
are used after a read error occurred (<a href="#7.19.7.2">7.19.7.2</a>, <a href="#7.19.7.7">7.19.7.7</a>, <a href="#7.24.3.2">7.24.3.2</a>).
-<!--page 515 indent 0-->
+<!--page 515 -->
<li> The file position indicator for a binary stream is used after a call to the ungetc
function where its value was zero before the call (<a href="#7.19.7.11">7.19.7.11</a>).
<li> The file position indicator for a stream is used after an error occurred during a call to
<li> The comparison function called by a searching or sorting utility function alters the
contents of the array being searched or sorted, or returns ordering values
inconsistently (<a href="#7.20.5">7.20.5</a>).
-<!--page 516 indent 0-->
+<!--page 516 -->
<li> The array being searched by the bsearch function does not have its elements in
proper order (<a href="#7.20.5.1">7.20.5.1</a>).
<li> The current conversion state is used by a multibyte/wide character conversion
<li> The towctrans function is called using a different LC_CTYPE category from the
one in effect for the call to the wctrans function that returned the description
(<a href="#7.25.3.2.1">7.25.3.2.1</a>).
-<!--page 517 indent 4-->
+<!--page 517 -->
</ul>
<a name="J.3" href="#J.3"><h3>J.3 Implementation-defined behavior</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A conforming implementation is required to document its choice of behavior in each of
the areas listed in this subclause. The following are implementation-defined:
<a name="J.3.1" href="#J.3.1"><h4>J.3.1 Translation</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> How a diagnostic is identified (<a href="#3.10">3.10</a>, <a href="#5.1.1.3">5.1.1.3</a>).
<li> Whether each nonempty sequence of white-space characters other than new-line is
</ul>
<a name="J.3.2" href="#J.3.2"><h4>J.3.2 Environment</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The mapping between physical source file multibyte characters and the source
character set in translation phase 1 (<a href="#5.1.1.2">5.1.1.2</a>).
</ul>
<a name="J.3.3" href="#J.3.3"><h4>J.3.3 Identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> Which additional multibyte characters may appear in identifiers and their
correspondence to universal character names (<a href="#6.4.2">6.4.2</a>).
<li> The number of significant initial characters in an identifier (<a href="#5.2.4.1">5.2.4.1</a>, <a href="#6.4.2">6.4.2</a>).
-<!--page 518 indent 4-->
+<!--page 518 -->
</ul>
<a name="J.3.4" href="#J.3.4"><h4>J.3.4 Characters</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The number of bits in a byte (<a href="#3.6">3.6</a>).
<li> The values of the members of the execution character set (<a href="#5.2.1">5.2.1</a>).
</ul>
<a name="J.3.5" href="#J.3.5"><h4>J.3.5 Integers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> Any extended integer types that exist in the implementation (<a href="#6.2.5">6.2.5</a>).
<li> Whether signed integer types are represented using sign and magnitude, two's
the same precision (<a href="#6.3.1.1">6.3.1.1</a>).
<li> The result of, or the signal raised by, converting an integer to a signed integer type
when the value cannot be represented in an object of that type (<a href="#6.3.1.3">6.3.1.3</a>).
-<!--page 519 indent 4-->
+<!--page 519 -->
<li> The results of some bitwise operations on signed integers (<a href="#6.5">6.5</a>).
</ul>
<a name="J.3.6" href="#J.3.6"><h4>J.3.6 Floating point</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The accuracy of the floating-point operations and of the library functions in
<a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> that return floating-point results (<a href="#5.2.4.2.2">5.2.4.2.2</a>).
</ul>
<a name="J.3.7" href="#J.3.7"><h4>J.3.7 Arrays and pointers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The result of converting a pointer to an integer or vice versa (<a href="#6.3.2.3">6.3.2.3</a>).
<li> The size of the result of subtracting two pointers to elements of the same array
(<a href="#6.5.6">6.5.6</a>).
-<!--page 520 indent 4-->
+<!--page 520 -->
</ul>
<a name="J.3.8" href="#J.3.8"><h4>J.3.8 Hints</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The extent to which suggestions made by using the register storage-class
specifier are effective (<a href="#6.7.1">6.7.1</a>).
</ul>
<a name="J.3.9" href="#J.3.9"><h4>J.3.9 Structures, unions, enumerations, and bit-fields</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> Whether a ''plain'' int bit-field is treated as a signed int bit-field or as an
unsigned int bit-field (<a href="#6.7.2">6.7.2</a>, <a href="#6.7.2.1">6.7.2.1</a>).
</ul>
<a name="J.3.10" href="#J.3.10"><h4>J.3.10 Qualifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> What constitutes an access to an object that has volatile-qualified type (<a href="#6.7.3">6.7.3</a>).
</ul>
<a name="J.3.11" href="#J.3.11"><h4>J.3.11 Preprocessing directives</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The locations within #pragma directives where header name preprocessing tokens
are recognized (<a href="#6.4">6.4</a>, <a href="#6.4.7">6.4.7</a>).
(<a href="#6.10.2">6.10.2</a>).
<li> The method by which preprocessing tokens (possibly resulting from macro
expansion) in a #include directive are combined into a header name (<a href="#6.10.2">6.10.2</a>).
-<!--page 521 indent 4-->
+<!--page 521 -->
<li> The nesting limit for #include processing (<a href="#6.10.2">6.10.2</a>).
<li> Whether the # operator inserts a \ character before the \ character that begins a
universal character name in a character constant or string literal (<a href="#6.10.3.2">6.10.3.2</a>).
</ul>
<a name="J.3.12" href="#J.3.12"><h4>J.3.12 Library functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> Any library facilities available to a freestanding program, other than the minimal set
required by clause 4 (<a href="#5.1.2.1">5.1.2.1</a>).
a second argument of zero (<a href="#7.12.10.2">7.12.10.2</a>).
<li> The base-2 logarithm of the modulus used by the remquo functions in reducing the
quotient (<a href="#7.12.10.3">7.12.10.3</a>).
-<!--page 522 indent 0-->
+<!--page 522 -->
<li> Whether a domain error occurs or zero is returned when a remquo function has a
second argument of zero (<a href="#7.12.10.3">7.12.10.3</a>).
<li> Whether the equivalent of signal(sig, SIG_DFL); is executed prior to the call
<li> The interpretation of a - character that is neither the first nor the last character, nor
the second where a ^ character is the first, in the scanlist for %[ conversion in the
fscanf or fwscanf function (<a href="#7.19.6.2">7.19.6.2</a>, <a href="#7.24.2.1">7.24.2.1</a>).
-<!--page 523 indent 4-->
+<!--page 523 -->
<li> The set of sequences matched by a %p conversion and the interpretation of the
corresponding input item in the fscanf or fwscanf function (<a href="#7.19.6.2">7.19.6.2</a>, <a href="#7.24.2.2">7.24.2.2</a>).
<li> The value to which the macro errno is set by the fgetpos, fsetpos, or ftell
</ul>
<a name="J.3.13" href="#J.3.13"><h4>J.3.13 Architecture</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The values or expressions assigned to the macros specified in the headers
<a href="#7.7"><float.h></a>, <a href="#7.10"><limits.h></a>, and <a href="#7.18"><stdint.h></a> (<a href="#5.2.4.2">5.2.4.2</a>, <a href="#7.18.2">7.18.2</a>, <a href="#7.18.3">7.18.3</a>).
<li> The number, order, and encoding of bytes in any object (when not explicitly specified
in this International Standard) (<a href="#6.2.6.1">6.2.6.1</a>).
<li> The value of the result of the sizeof operator (<a href="#6.5.3.4">6.5.3.4</a>).
-<!--page 524 indent 4-->
+<!--page 524 -->
</ul>
<a name="J.4" href="#J.4"><h3>J.4 Locale-specific behavior</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following characteristics of a hosted environment are locale-specific and are required
to be documented by the implementation:
<ul>
<li> The formats for time and date (<a href="#7.23.3.5">7.23.3.5</a>, <a href="#7.24.5.1">7.24.5.1</a>).
<li> Character mappings that are supported by the towctrans function (<a href="#7.25.1">7.25.1</a>).
<li> Character classifications that are supported by the iswctype function (<a href="#7.25.1">7.25.1</a>).
-<!--page 525 indent 4-->
+<!--page 525 -->
</ul>
<a name="J.5" href="#J.5"><h3>J.5 Common extensions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following extensions are widely used in many systems, but are not portable to all
implementations. The inclusion of any extension that may cause a strictly conforming
program to become invalid renders an implementation nonconforming. Examples of such
predefined macros with names that do not begin with an underscore.
<a name="J.5.1" href="#J.5.1"><h4>J.5.1 Environment arguments</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In a hosted environment, the main function receives a third argument, char *envp[],
that points to a null-terminated array of pointers to char, each of which points to a string
that provides information about the environment for this execution of the program
(<a href="#5.1.2.2.1">5.1.2.2.1</a>).
<a name="J.5.2" href="#J.5.2"><h4>J.5.2 Specialized identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Characters other than the underscore _, letters, and digits, that are not part of the basic
source character set (such as the dollar sign $, or characters in national character sets)
may appear in an identifier (<a href="#6.4.2">6.4.2</a>).
<a name="J.5.3" href="#J.5.3"><h4>J.5.3 Lengths and cases of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
All characters in identifiers (with or without external linkage) are significant (<a href="#6.4.2">6.4.2</a>).
<a name="J.5.4" href="#J.5.4"><h4>J.5.4 Scopes of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A function identifier, or the identifier of an object the declaration of which contains the
keyword extern, has file scope (<a href="#6.2.1">6.2.1</a>).
<a name="J.5.5" href="#J.5.5"><h4>J.5.5 Writable string literals</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
String literals are modifiable (in which case, identical string literals should denote distinct
objects) (<a href="#6.4.5">6.4.5</a>).
<a name="J.5.6" href="#J.5.6"><h4>J.5.6 Other arithmetic types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Additional arithmetic types, such as __int128 or double double, and their
appropriate conversions are defined (<a href="#6.2.5">6.2.5</a>, <a href="#6.3.1">6.3.1</a>). Additional floating types may have
more range or precision than long double, may be used for evaluating expressions of
other floating types, and may be used to define float_t or double_t.
-<!--page 526 indent 4-->
+<!--page 526 -->
<a name="J.5.7" href="#J.5.7"><h4>J.5.7 Function pointer casts</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A pointer to an object or to void may be cast to a pointer to a function, allowing data to
be invoked as a function (<a href="#6.5.4">6.5.4</a>).
-<p><!--para 2-->
+<p><!--para 2 -->
A pointer to a function may be cast to a pointer to an object or to void, allowing a
function to be inspected or modified (for example, by a debugger) (<a href="#6.5.4">6.5.4</a>).
<a name="J.5.8" href="#J.5.8"><h4>J.5.8 Extended bit-field types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A bit-field may be declared with a type other than _Bool, unsigned int, or
signed int, with an appropriate maximum width (<a href="#6.7.2.1">6.7.2.1</a>).
<a name="J.5.9" href="#J.5.9"><h4>J.5.9 The fortran keyword</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The fortran function specifier may be used in a function declaration to indicate that
calls suitable for FORTRAN should be generated, or that a different representation for the
external name is to be generated (<a href="#6.7.4">6.7.4</a>).
<a name="J.5.10" href="#J.5.10"><h4>J.5.10 The asm keyword</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The asm keyword may be used to insert assembly language directly into the translator
output (<a href="#6.8">6.8</a>). The most common implementation is via a statement of the form:
<pre>
asm ( character-string-literal );</pre>
<a name="J.5.11" href="#J.5.11"><h4>J.5.11 Multiple external definitions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
There may be more than one external definition for the identifier of an object, with or
without the explicit use of the keyword extern; if the definitions disagree, or more than
one is initialized, the behavior is undefined (<a href="#6.9.2">6.9.2</a>).
<a name="J.5.12" href="#J.5.12"><h4>J.5.12 Predefined macro names</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macro names that do not begin with an underscore, describing the translation and
execution environments, are defined by the implementation before translation begins
(<a href="#6.10.8">6.10.8</a>).
<a name="J.5.13" href="#J.5.13"><h4>J.5.13 Floating-point status flags</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
If any floating-point status flags are set on normal termination after all calls to functions
registered by the atexit function have been made (see <a href="#7.20.4.3">7.20.4.3</a>), the implementation
writes some diagnostics indicating the fact to the stderr stream, if it is still open,
-<!--page 527 indent 4-->
+<!--page 527 -->
<a name="J.5.14" href="#J.5.14"><h4>J.5.14 Extra arguments for signal handlers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Handlers for specific signals are called with extra arguments in addition to the signal
number (<a href="#7.14.1.1">7.14.1.1</a>).
<a name="J.5.15" href="#J.5.15"><h4>J.5.15 Additional stream types and file-opening modes</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Additional mappings from files to streams are supported (<a href="#7.19.2">7.19.2</a>).
-<p><!--para 2-->
+<p><!--para 2 -->
Additional file-opening modes may be specified by characters appended to the mode
argument of the fopen function (<a href="#7.19.5.3">7.19.5.3</a>).
<a name="J.5.16" href="#J.5.16"><h4>J.5.16 Defined file position indicator</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The file position indicator is decremented by each successful call to the ungetc or
ungetwc function for a text stream, except if its value was zero before a call (<a href="#7.19.7.11">7.19.7.11</a>,
<a href="#7.24.3.10">7.24.3.10</a>).
<a name="J.5.17" href="#J.5.17"><h4>J.5.17 Math error reporting</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Functions declared in <a href="#7.3"><complex.h></a> and <a href="#7.12"><math.h></a> raise SIGFPE to report errors
instead of, or in addition to, setting errno or raising floating-point exceptions (<a href="#7.3">7.3</a>,
<a href="#7.12">7.12</a>).
-<!--page 528 indent -1-->
+<!--page 528 -->
<a name="Bibliography" href="#Bibliography"><h2>Bibliography</h2></a>
<ol>
preparation of programming language standards.
<li> ISO/IEC 10646-1:1993, Information technology -- Universal Multiple-Octet
Coded Character Set (UCS) -- Part 1: Architecture and Basic Multilingual Plane.
-<!--page 529 indent -1-->
+<!--page 529 -->
<li> ISO/IEC 10646-1/COR1:1996, Technical Corrigendum 1 to
ISO/IEC 10646-1:1993.
<li> ISO/IEC 10646-1/COR2:1998, Technical Corrigendum 2 to
Cherokee.
<li> ISO/IEC 10967-1:1994, Information technology -- Language independent
arithmetic -- Part 1: Integer and floating point arithmetic.
-<!--page 530 indent 0-->
-<!--page 531 indent 0-->
+<!--page 530 -->
+<!--page 531 -->
</ol>
<a name="Index" href="#Index"><h2>Index</h2></a>
++ (prefix increment operator), <a href="#6.3.2.1">6.3.2.1</a>, <a href="#6.5.3.1">6.5.3.1</a> <a href="#7.18"><stdint.h></a> header, <a href="#4">4</a>, <a href="#5.2.4.2">5.2.4.2</a>, <a href="#6.10.1">6.10.1</a>, <a href="#7.8">7.8</a>,
+= (addition assignment operator), <a href="#6.5.16.2">6.5.16.2</a> <a href="#7.18">7.18</a>, <a href="#7.26.8">7.26.8</a>
, (comma operator), <a href="#6.5.17">6.5.17</a>
-<!--page 532 indent 0-->
+<!--page 532 -->
<a href="#7.19"><stdio.h></a> header, <a href="#5.2.4.2.2">5.2.4.2.2</a>, <a href="#7.19">7.19</a>, <a href="#7.26.9">7.26.9</a>, <a href="#F">F</a> __cplusplus macro, <a href="#6.10.8">6.10.8</a>
<a href="#7.20"><stdlib.h></a> header, <a href="#5.2.4.2.2">5.2.4.2.2</a>, <a href="#7.20">7.20</a>, <a href="#7.26.10">7.26.10</a>, <a href="#F">F</a> __DATE__ macro, <a href="#6.10.8">6.10.8</a>
<a href="#7.21"><string.h></a> header, <a href="#7.21">7.21</a>, <a href="#7.26.11">7.26.11</a> __FILE__ macro, <a href="#6.10.8">6.10.8</a>, <a href="#7.2.1.1">7.2.1.1</a>
<a href="#6.5.16.2">6.5.16.2</a> real, <a href="#7.12.7">7.12.7</a>, <a href="#F.9.4">F.9.4</a>
__bool_true_false_are_defined abstract declarator, <a href="#6.7.6">6.7.6</a>
macro, <a href="#7.16">7.16</a> abstract machine, <a href="#5.1.2.3">5.1.2.3</a>
-<!--page 533 indent 0-->
+<!--page 533 -->
access, <a href="#3.1">3.1</a>, <a href="#6.7.3">6.7.3</a> array
accuracy, see floating-point accuracy argument, <a href="#6.9.1">6.9.1</a>
acos functions, <a href="#7.12.4.1">7.12.4.1</a>, <a href="#F.9.1.1">F.9.1.1</a> declarator, <a href="#6.7.5.2">6.7.5.2</a>
unary, <a href="#6.5.3.3">6.5.3.3</a> backspace escape sequence (\b), <a href="#5.2.2">5.2.2</a>, <a href="#6.4.4.4">6.4.4.4</a>
arithmetic types, <a href="#6.2.5">6.2.5</a> basic character set, <a href="#3.6">3.6</a>, <a href="#3.7.2">3.7.2</a>, <a href="#5.2.1">5.2.1</a>
arithmetic, pointer, <a href="#6.5.6">6.5.6</a> basic types, <a href="#6.2.5">6.2.5</a>
-<!--page 534 indent 0-->
+<!--page 534 -->
behavior, <a href="#3.4">3.4</a> call by value, <a href="#6.5.2.2">6.5.2.2</a>
binary streams, <a href="#7.19.2">7.19.2</a>, <a href="#7.19.7.11">7.19.7.11</a>, <a href="#7.19.9.2">7.19.9.2</a>, calloc function, <a href="#7.20.3">7.20.3</a>, <a href="#7.20.3.1">7.20.3.1</a>, <a href="#7.20.3.2">7.20.3.2</a>,
<a href="#7.19.9.4">7.19.9.4</a> <a href="#7.20.3.4">7.20.3.4</a>
type-generic macro for, <a href="#7.22">7.22</a> wide character, <a href="#7.25.2.1">7.25.2.1</a>
calendar time, <a href="#7.23.1">7.23.1</a>, <a href="#7.23.2.2">7.23.2.2</a>, <a href="#7.23.2.3">7.23.2.3</a>, <a href="#7.23.2.4">7.23.2.4</a>, extensible, <a href="#7.25.2.2">7.25.2.2</a>
<a href="#7.23.3.2">7.23.3.2</a>, <a href="#7.23.3.3">7.23.3.3</a>, <a href="#7.23.3.4">7.23.3.4</a> character constant, <a href="#5.1.1.2">5.1.1.2</a>, <a href="#5.2.1">5.2.1</a>, <a href="#6.4.4.4">6.4.4.4</a>
-<!--page 535 indent 0-->
+<!--page 535 -->
character display semantics, <a href="#5.2.2">5.2.2</a> complex.h header, <a href="#5.2.4.2.2">5.2.4.2.2</a>, <a href="#7.3">7.3</a>, <a href="#7.22">7.22</a>, <a href="#7.26.1">7.26.1</a>,
character handling header, <a href="#7.4">7.4</a>, <a href="#7.11.1.1">7.11.1.1</a> <a href="#G.6">G.6</a>, <a href="#J.5.17">J.5.17</a>
character input/output functions, <a href="#7.19.7">7.19.7</a> compliance, see conformance
complex type conversion, <a href="#6.3.1.6">6.3.1.6</a>, <a href="#6.3.1.7">6.3.1.7</a> explicit, <a href="#6.3">6.3</a>
complex type domain, <a href="#6.2.5">6.2.5</a> function, <a href="#6.3.2.1">6.3.2.1</a>
complex types, <a href="#6.2.5">6.2.5</a>, <a href="#6.7.2">6.7.2</a>, <a href="#G">G</a> function argument, <a href="#6.5.2.2">6.5.2.2</a>, <a href="#6.9.1">6.9.1</a>
-<!--page 536 indent 0-->
+<!--page 536 -->
function designators, <a href="#6.3.2.1">6.3.2.1</a> type-generic macro for, <a href="#7.22">7.22</a>
function parameter, <a href="#6.9.1">6.9.1</a> csinh functions, <a href="#7.3.6.5">7.3.6.5</a>, <a href="#G.6.2.5">G.6.2.5</a>
imaginary, <a href="#G.4.1">G.4.1</a> type-generic macro for, <a href="#7.22">7.22</a>
creal functions, <a href="#7.3.9.5">7.3.9.5</a>, <a href="#G.6">G.6</a> definition, <a href="#6.7">6.7</a>
creal type-generic macro, <a href="#7.22">7.22</a>, <a href="#G.7">G.7</a> function, <a href="#6.9.1">6.9.1</a>
csin functions, <a href="#7.3.5.5">7.3.5.5</a>, <a href="#G.6">G.6</a> derived declarator types, <a href="#6.2.5">6.2.5</a>
-<!--page 537 indent 0-->
+<!--page 537 -->
derived types, <a href="#6.2.5">6.2.5</a> end-of-file indicator, <a href="#7.19.1">7.19.1</a>, <a href="#7.19.5.3">7.19.5.3</a>, <a href="#7.19.7.1">7.19.7.1</a>,
designated initializer, <a href="#6.7.8">6.7.8</a> <a href="#7.19.7.5">7.19.7.5</a>, <a href="#7.19.7.6">7.19.7.6</a>, <a href="#7.19.7.11">7.19.7.11</a>, <a href="#7.19.9.2">7.19.9.2</a>,
destringizing, <a href="#6.10.9">6.10.9</a> <a href="#7.19.9.3">7.19.9.3</a>, <a href="#7.19.10.1">7.19.10.1</a>, <a href="#7.19.10.2">7.19.10.2</a>, <a href="#7.24.3.1">7.24.3.1</a>,
encoding error, <a href="#7.19.3">7.19.3</a>, <a href="#7.24.3.1">7.24.3.1</a>, <a href="#7.24.3.3">7.24.3.3</a>, domain, see domain error
<a href="#7.24.6.3.2">7.24.6.3.2</a>, <a href="#7.24.6.3.3">7.24.6.3.3</a>, <a href="#7.24.6.4.1">7.24.6.4.1</a>, <a href="#7.24.6.4.2">7.24.6.4.2</a> encoding, see encoding error
end-of-file, <a href="#7.24.1">7.24.1</a> range, see range error
-<!--page 538 indent 0-->
+<!--page 538 -->
error conditions, <a href="#7.12.1">7.12.1</a> extended characters, <a href="#5.2.1">5.2.1</a>
error functions, <a href="#7.12.8">7.12.8</a>, <a href="#F.9.5">F.9.5</a> extended integer types, <a href="#6.2.5">6.2.5</a>, <a href="#6.3.1.1">6.3.1.1</a>, <a href="#6.4.4.1">6.4.4.1</a>,
error indicator, <a href="#7.19.1">7.19.1</a>, <a href="#7.19.5.3">7.19.5.3</a>, <a href="#7.19.7.1">7.19.7.1</a>, <a href="#7.18">7.18</a>
unary, <a href="#6.5.3">6.5.3</a> fesetround function, <a href="#7.6">7.6</a>, <a href="#7.6.3.2">7.6.3.2</a>, <a href="#F.3">F.3</a>
expression statement, <a href="#6.8.3">6.8.3</a> fetestexcept function, <a href="#7.6.2">7.6.2</a>, <a href="#7.6.2.5">7.6.2.5</a>, <a href="#F.3">F.3</a>
extended character set, <a href="#3.7.2">3.7.2</a>, <a href="#5.2.1">5.2.1</a>, <a href="#5.2.1.2">5.2.1.2</a> feupdateenv function, <a href="#7.6.4.2">7.6.4.2</a>, <a href="#7.6.4.4">7.6.4.4</a>, <a href="#F.3">F.3</a>
-<!--page 539 indent 0-->
+<!--page 539 -->
fexcept_t type, <a href="#7.6">7.6</a>, <a href="#F.3">F.3</a> floating-point status flag, <a href="#7.6">7.6</a>, <a href="#F.7.6">F.7.6</a>
fflush function, <a href="#7.19.5.2">7.19.5.2</a>, <a href="#7.19.5.3">7.19.5.3</a> floor functions, <a href="#7.12.9.2">7.12.9.2</a>, <a href="#F.9.6.2">F.9.6.2</a>
fgetc function, <a href="#7.19.1">7.19.1</a>, <a href="#7.19.3">7.19.3</a>, <a href="#7.19.7.1">7.19.7.1</a>, floor type-generic macro, <a href="#7.22">7.22</a>
floating-point exception, <a href="#7.6">7.6</a>, <a href="#7.6.2">7.6.2</a>, <a href="#F.9">F.9</a> FP_ZERO macro, <a href="#7.12">7.12</a>, <a href="#F.3">F.3</a>
floating-point number, <a href="#5.2.4.2.2">5.2.4.2.2</a>, <a href="#6.2.5">6.2.5</a> fpclassify macro, <a href="#7.12.3.1">7.12.3.1</a>, <a href="#F.3">F.3</a>
floating-point rounding mode, <a href="#5.2.4.2.2">5.2.4.2.2</a> fpos_t type, <a href="#7.19.1">7.19.1</a>, <a href="#7.19.2">7.19.2</a>
-<!--page 540 indent 0-->
+<!--page 540 -->
fprintf function, <a href="#7.8.1">7.8.1</a>, <a href="#7.19.1">7.19.1</a>, <a href="#7.19.6.1">7.19.6.1</a>, language, <a href="#6.11">6.11</a>
<a href="#7.19.6.2">7.19.6.2</a>, <a href="#7.19.6.3">7.19.6.3</a>, <a href="#7.19.6.5">7.19.6.5</a>, <a href="#7.19.6.6">7.19.6.6</a>, library, <a href="#7.26">7.26</a>
<a href="#7.19.6.8">7.19.6.8</a>, <a href="#7.24.2.2">7.24.2.2</a>, <a href="#F.3">F.3</a> fwide function, <a href="#7.19.2">7.19.2</a>, <a href="#7.24.3.5">7.24.3.5</a>
function-call operator (( )), <a href="#6.5.2.2">6.5.2.2</a> real, <a href="#7.12.5">7.12.5</a>, <a href="#F.9.2">F.9.2</a>
function-like macro, <a href="#6.10.3">6.10.3</a> hypot functions, <a href="#7.12.7.3">7.12.7.3</a>, <a href="#F.9.4.3">F.9.4.3</a>
future directions hypot type-generic macro, <a href="#7.22">7.22</a>
-<!--page 541 indent 0-->
+<!--page 541 -->
<a href="#I">I</a> macro, <a href="#7.3.1">7.3.1</a>, <a href="#7.3.9.4">7.3.9.4</a>, <a href="#G.6">G.6</a> initial position, <a href="#5.2.2">5.2.2</a>
identifier, <a href="#6.4.2.1">6.4.2.1</a>, <a href="#6.5.1">6.5.1</a> initial shift state, <a href="#5.2.1.2">5.2.1.2</a>
linkage, see linkage initialization, <a href="#5.1.2">5.1.2</a>, <a href="#6.2.4">6.2.4</a>, <a href="#6.3.2.1">6.3.2.1</a>, <a href="#6.5.2.5">6.5.2.5</a>, <a href="#6.7.8">6.7.8</a>,
indirection operator (*), <a href="#6.5.2.1">6.5.2.1</a>, <a href="#6.5.3.2">6.5.3.2</a> interrupt, <a href="#5.2.3">5.2.3</a>
inequality operator (!=), <a href="#6.5.9">6.5.9</a> INTMAX_C macro, <a href="#7.18.4.2">7.18.4.2</a>
INFINITY macro, <a href="#7.3.9.4">7.3.9.4</a>, <a href="#7.12">7.12</a>, <a href="#F.2.1">F.2.1</a> INTMAX_MAX macro, <a href="#7.8.2.3">7.8.2.3</a>, <a href="#7.8.2.4">7.8.2.4</a>, <a href="#7.18.2.5">7.18.2.5</a>
-<!--page 542 indent 0-->
+<!--page 542 -->
INTMAX_MIN macro, <a href="#7.8.2.3">7.8.2.3</a>, <a href="#7.8.2.4">7.8.2.4</a>, <a href="#7.18.2.5">7.18.2.5</a> iswalpha function, <a href="#7.25.2.1.1">7.25.2.1.1</a>, <a href="#7.25.2.1.2">7.25.2.1.2</a>,
intmax_t type, <a href="#7.18.1.5">7.18.1.5</a>, <a href="#7.19.6.1">7.19.6.1</a>, <a href="#7.19.6.2">7.19.6.2</a>, <a href="#7.25.2.2.1">7.25.2.2.1</a>
<a href="#7.24.2.1">7.24.2.1</a>, <a href="#7.24.2.2">7.24.2.2</a> iswblank function, <a href="#7.25.2.1.3">7.25.2.1.3</a>, <a href="#7.25.2.2.1">7.25.2.2.1</a>
<a href="#7.4.2.2">7.4.2.2</a> LC_MONETARY macro, <a href="#7.11">7.11</a>, <a href="#7.11.1.1">7.11.1.1</a>, <a href="#7.11.2.1">7.11.2.1</a>
iswalnum function, <a href="#7.25.2.1.1">7.25.2.1.1</a>, <a href="#7.25.2.1.9">7.25.2.1.9</a>, LC_NUMERIC macro, <a href="#7.11">7.11</a>, <a href="#7.11.1.1">7.11.1.1</a>, <a href="#7.11.2.1">7.11.2.1</a>
<a href="#7.25.2.1.10">7.25.2.1.10</a>, <a href="#7.25.2.2.1">7.25.2.2.1</a> LC_TIME macro, <a href="#7.11">7.11</a>, <a href="#7.11.1.1">7.11.1.1</a>, <a href="#7.23.3.5">7.23.3.5</a>
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+<!--page 543 -->
lconv structure type, <a href="#7.11">7.11</a> llabs function, <a href="#7.20.6.1">7.20.6.1</a>
LDBL_DIG macro, <a href="#5.2.4.2.2">5.2.4.2.2</a> lldiv function, <a href="#7.20.6.2">7.20.6.2</a>
LDBL_EPSILON macro, <a href="#5.2.4.2.2">5.2.4.2.2</a> lldiv_t type, <a href="#7.20">7.20</a>
preprocessing directive, <a href="#6.10">6.10</a> <a href="#6.3.1.4">6.3.1.4</a>, <a href="#6.3.1.8">6.3.1.8</a>
linkage, <a href="#6.2.2">6.2.2</a>, <a href="#6.7">6.7</a>, <a href="#6.7.4">6.7.4</a>, <a href="#6.7.5.2">6.7.5.2</a>, <a href="#6.9">6.9</a>, <a href="#6.9.2">6.9.2</a>, long integer suffix, l or <a href="#L">L</a>, <a href="#6.4.4.1">6.4.4.1</a>
<a href="#6.11.2">6.11.2</a> long long int type, <a href="#6.2.5">6.2.5</a>, <a href="#6.3.1.1">6.3.1.1</a>, <a href="#6.7.2">6.7.2</a>,
-<!--page 544 indent 0-->
+<!--page 544 -->
<a href="#7.19.6.1">7.19.6.1</a>, <a href="#7.19.6.2">7.19.6.2</a>, <a href="#7.24.2.1">7.24.2.1</a>, <a href="#7.24.2.2">7.24.2.2</a> mbsinit function, <a href="#7.24.6.2.1">7.24.6.2.1</a>
long long int type conversion, <a href="#6.3.1.1">6.3.1.1</a>, mbsrtowcs function, <a href="#7.24.6.4.1">7.24.6.4.1</a>
<a href="#6.3.1.3">6.3.1.3</a>, <a href="#6.3.1.4">6.3.1.4</a>, <a href="#6.3.1.8">6.3.1.8</a> mbstate_t type, <a href="#7.19.2">7.19.2</a>, <a href="#7.19.3">7.19.3</a>, <a href="#7.19.6.1">7.19.6.1</a>,
mbrtowc function, <a href="#7.19.3">7.19.3</a>, <a href="#7.19.6.1">7.19.6.1</a>, <a href="#7.19.6.2">7.19.6.2</a>, external, <a href="#5.2.4.1">5.2.4.1</a>, <a href="#6.4.2.1">6.4.2.1</a>, <a href="#6.11.3">6.11.3</a>
<a href="#7.24.2.1">7.24.2.1</a>, <a href="#7.24.2.2">7.24.2.2</a>, <a href="#7.24.6.3.1">7.24.6.3.1</a>, <a href="#7.24.6.3.2">7.24.6.3.2</a>, file, <a href="#7.19.3">7.19.3</a>
<a href="#7.24.6.4.1">7.24.6.4.1</a> internal, <a href="#5.2.4.1">5.2.4.1</a>, <a href="#6.4.2.1">6.4.2.1</a>
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+<!--page 545 -->
label, <a href="#6.2.3">6.2.3</a> octal-character escape sequence (\octal digits),
structure/union member, <a href="#6.2.3">6.2.3</a> <a href="#6.4.4.4">6.4.4.4</a>
name spaces, <a href="#6.2.3">6.2.3</a> offsetof macro, <a href="#7.17">7.17</a>
obsolescence, <a href="#6.11">6.11</a>, <a href="#7.26">7.26</a> parenthesized expression, <a href="#6.5.1">6.5.1</a>
octal constant, <a href="#6.4.4.1">6.4.4.1</a> parse state, <a href="#7.19.2">7.19.2</a>
octal digit, <a href="#6.4.4.1">6.4.4.1</a>, <a href="#6.4.4.4">6.4.4.4</a> permitted form of initializer, <a href="#6.6">6.6</a>
-<!--page 546 indent 0-->
+<!--page 546 -->
perror function, <a href="#7.19.10.4">7.19.10.4</a> PRIcPTR macros, <a href="#7.8.1">7.8.1</a>
phase angle, complex, <a href="#7.3.9.1">7.3.9.1</a> primary expression, <a href="#6.5.1">6.5.1</a>
physical source lines, <a href="#5.1.1.2">5.1.1.2</a> printf function, <a href="#7.19.1">7.19.1</a>, <a href="#7.19.6.3">7.19.6.3</a>, <a href="#7.19.6.10">7.19.6.10</a>
PRIcLEASTN macros, <a href="#7.8.1">7.8.1</a> <a href="#7.12.7.4">7.12.7.4</a>, <a href="#7.12.8.2">7.12.8.2</a>, <a href="#7.12.8.3">7.12.8.3</a>, <a href="#7.12.8.4">7.12.8.4</a>,
PRIcMAX macros, <a href="#7.8.1">7.8.1</a> <a href="#7.12.9.5">7.12.9.5</a>, <a href="#7.12.9.7">7.12.9.7</a>, <a href="#7.12.11.3">7.12.11.3</a>, <a href="#7.12.12.1">7.12.12.1</a>,
PRIcN macros, <a href="#7.8.1">7.8.1</a> <a href="#7.12.13.1">7.12.13.1</a>
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rank, see integer conversion rank same scope, <a href="#6.2.1">6.2.1</a>
real floating type conversion, <a href="#6.3.1.4">6.3.1.4</a>, <a href="#6.3.1.5">6.3.1.5</a>, save calling environment function, <a href="#7.13.1">7.13.1</a>
<a href="#6.3.1.7">6.3.1.7</a>, <a href="#F.3">F.3</a>, <a href="#F.4">F.4</a> scalar types, <a href="#6.2.5">6.2.5</a>
rounding mode, floating point, <a href="#5.2.4.2.2">5.2.4.2.2</a> <a href="#6.3.1.4">6.3.1.4</a>, <a href="#6.3.1.8">6.3.1.8</a>
rvalue, <a href="#6.3.2.1">6.3.2.1</a> SHRT_MAX macro, <a href="#5.2.4.2.1">5.2.4.2.1</a>
SHRT_MIN macro, <a href="#5.2.4.2.1">5.2.4.2.1</a>
-<!--page 548 indent 0-->
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side effects, <a href="#5.1.2.3">5.1.2.3</a>, <a href="#6.5">6.5</a> source lines, <a href="#5.1.1.2">5.1.1.2</a>
SIG_ATOMIC_MAX macro, <a href="#7.18.3">7.18.3</a> source text, <a href="#5.1.1.2">5.1.1.2</a>
SIG_ATOMIC_MIN macro, <a href="#7.18.3">7.18.3</a> space character (' '), <a href="#5.1.1.2">5.1.1.2</a>, <a href="#5.2.1">5.2.1</a>, <a href="#6.4">6.4</a>, <a href="#7.4.1.3">7.4.1.3</a>,
source file, <a href="#5.1.1.1">5.1.1.1</a> compound, <a href="#6.8.2">6.8.2</a>
name, <a href="#6.10.4">6.10.4</a>, <a href="#6.10.8">6.10.8</a> continue, <a href="#6.8.6.2">6.8.6.2</a>
source file inclusion, <a href="#6.10.2">6.10.2</a> do, <a href="#6.8.5.2">6.8.5.2</a>
-<!--page 549 indent 0-->
+<!--page 549 -->
else, <a href="#6.8.4.1">6.8.4.1</a> strictly conforming program, <a href="#4">4</a>
expression, <a href="#6.8.3">6.8.3</a> string, <a href="#7.1.1">7.1.1</a>
for, <a href="#6.8.5.3">6.8.5.3</a> comparison functions, <a href="#7.21.4">7.21.4</a>
strerror function, <a href="#7.19.10.4">7.19.10.4</a>, <a href="#7.21.6.2">7.21.6.2</a> strxfrm function, <a href="#7.11.1.1">7.11.1.1</a>, <a href="#7.21.4.5">7.21.4.5</a>
strftime function, <a href="#7.11.1.1">7.11.1.1</a>, <a href="#7.23.3">7.23.3</a>, <a href="#7.23.3.5">7.23.3.5</a>, subscripting, <a href="#6.5.2.1">6.5.2.1</a>
<a href="#7.24.5.1">7.24.5.1</a> subtraction assignment operator (-=), <a href="#6.5.16.2">6.5.16.2</a>
-<!--page 550 indent 0-->
+<!--page 550 -->
subtraction operator (-), <a href="#6.5.6">6.5.6</a>, <a href="#F.3">F.3</a>, <a href="#G.5.2">G.5.2</a> tolower function, <a href="#7.4.2.1">7.4.2.1</a>
suffix toupper function, <a href="#7.4.2.2">7.4.2.2</a>
floating constant, <a href="#6.4.4.2">6.4.4.2</a> towctrans function, <a href="#7.25.3.2.1">7.25.3.2.1</a>, <a href="#7.25.3.2.2">7.25.3.2.2</a>
token, <a href="#5.1.1.2">5.1.1.2</a>, <a href="#6.4">6.4</a>, see also preprocessing tokens UINT_MAX macro, <a href="#5.2.4.2.1">5.2.4.2.1</a>
token concatenation, <a href="#6.10.3.3">6.10.3.3</a> UINTMAX_C macro, <a href="#7.18.4.2">7.18.4.2</a>
token pasting, <a href="#6.10.3.3">6.10.3.3</a> UINTMAX_MAX macro, <a href="#7.8.2.3">7.8.2.3</a>, <a href="#7.8.2.4">7.8.2.4</a>, <a href="#7.18.2.5">7.18.2.5</a>
-<!--page 551 indent 0-->
+<!--page 551 -->
uintmax_t type, <a href="#7.18.1.5">7.18.1.5</a>, <a href="#7.19.6.1">7.19.6.1</a>, <a href="#7.19.6.2">7.19.6.2</a>, USHRT_MAX macro, <a href="#5.2.4.2.1">5.2.4.2.1</a>
<a href="#7.24.2.1">7.24.2.1</a>, <a href="#7.24.2.2">7.24.2.2</a> usual arithmetic conversions, <a href="#6.3.1.8">6.3.1.8</a>, <a href="#6.5.5">6.5.5</a>, <a href="#6.5.6">6.5.6</a>,
UINTN_C macros, <a href="#7.18.4.1">7.18.4.1</a> <a href="#6.5.8">6.5.8</a>, <a href="#6.5.9">6.5.9</a>, <a href="#6.5.10">6.5.10</a>, <a href="#6.5.11">6.5.11</a>, <a href="#6.5.12">6.5.12</a>, <a href="#6.5.15">6.5.15</a>
unspecified value, <a href="#3.17.3">3.17.3</a> vsnprintf function, <a href="#7.19.6.8">7.19.6.8</a>, <a href="#7.19.6.12">7.19.6.12</a>
uppercase letter, <a href="#5.2.1">5.2.1</a> vsprintf function, <a href="#7.19.6.8">7.19.6.8</a>, <a href="#7.19.6.13">7.19.6.13</a>
use of library functions, <a href="#7.1.4">7.1.4</a> vsscanf function, <a href="#7.19.6.8">7.19.6.8</a>, <a href="#7.19.6.14">7.19.6.14</a>
-<!--page 552 indent 0-->
+<!--page 552 -->
vswprintf function, <a href="#7.24.2.7">7.24.2.7</a> wctype.h header, <a href="#7.25">7.25</a>, <a href="#7.26.13">7.26.13</a>
vswscanf function, <a href="#7.24.2.8">7.24.2.8</a> wctype_t type, <a href="#7.25.1">7.25.1</a>, <a href="#7.25.2.2.2">7.25.2.2.2</a>
vwprintf function, <a href="#7.19.1">7.19.1</a>, <a href="#7.24.2.9">7.24.2.9</a> WEOF macro, <a href="#7.24.1">7.24.1</a>, <a href="#7.24.3.1">7.24.3.1</a>, <a href="#7.24.3.3">7.24.3.3</a>, <a href="#7.24.3.6">7.24.3.6</a>,
<html><head><title>N1548 December 2, 2010 ISO/IEC 9899:201x</title></head><body>
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N1548 Committee Draft -- December 2, 2010 ISO/IEC 9899:201x
Changes from the previous draft (N1256) are indicated by ''diff marks'' in the right
margin: deleted text is marked with ''*'', new or changed text with '' ''.
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-<!--page 3 indent 0-->
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+<!--page 3 -->
</pre>
<a name="Contents" href="#Contents"><h2>Contents</h2></a>
<li><a href="#6.4.7"> 6.4.7 Header names</a>
<li><a href="#6.4.8"> 6.4.8 Preprocessing numbers</a>
<li><a href="#6.4.9"> 6.4.9 Comments</a>
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+<!--page 4 -->
</ul>
<li><a href="#6.5"> 6.5 Expressions</a>
<ul>
<li><a href="#6.10.1"> 6.10.1 Conditional inclusion</a>
<li><a href="#6.10.2"> 6.10.2 Source file inclusion</a>
<li><a href="#6.10.3"> 6.10.3 Macro replacement</a>
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+<!--page 5 -->
<li><a href="#6.10.4"> 6.10.4 Line control</a>
<li><a href="#6.10.5"> 6.10.5 Error directive</a>
<li><a href="#6.10.6"> 6.10.6 Pragma directive</a>
<li><a href="#7.6.4"> 7.6.4 Environment</a>
</ul>
<li><a href="#7.7"> 7.7 Characteristics of floating types <float.h></a>
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<li><a href="#7.8"> 7.8 Format conversion of integer types <inttypes.h></a>
<ul>
<li><a href="#7.8.1"> 7.8.1 Macros for format specifiers</a>
<li><a href="#7.18"> 7.18 Boolean type and values <stdbool.h></a>
<li><a href="#7.19"> 7.19 Common definitions <stddef.h></a>
<li><a href="#7.20"> 7.20 Integer types <stdint.h></a>
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<ul>
<li><a href="#7.20.1"> 7.20.1 Integer types</a>
<li><a href="#7.20.2"> 7.20.2 Limits of specified-width integer types</a>
<li><a href="#7.26.1"> 7.26.1 Components of time</a>
<li><a href="#7.26.2"> 7.26.2 Time manipulation functions</a>
<li><a href="#7.26.3"> 7.26.3 Time conversion functions</a>
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</ul>
<li><a href="#7.27"> 7.27 Unicode utilities <uchar.h></a>
<ul>
<li><a href="#7.30.9"> 7.30.9 Input/output <stdio.h></a>
<li><a href="#7.30.10"> 7.30.10 General utilities <stdlib.h></a>
<li><a href="#7.30.11"> 7.30.11 String handling <string.h></a>
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<li><a href="#7.30.12"> 7.30.12 Extended multibyte and wide character utilities <wchar.h></a>
<li><a href="#7.30.13"> 7.30.13 Wide character classification and mapping utilities <wctype.h></a>
</ul>
<li><a href="#D.2"> D.2 Ranges of characters disallowed initially</a>
</ul>
<li><a href="#E">Annex E (informative) Implementation limits</a>
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<li><a href="#F">Annex F (normative) IEC 60559 floating-point arithmetic</a>
<ul>
<li><a href="#F.1"> F.1 Introduction</a>
<li><a href="#H.1"> H.1 Introduction</a>
<li><a href="#H.2"> H.2 Types</a>
<li><a href="#H.3"> H.3 Notification</a>
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</ul>
<li><a href="#I">Annex I (informative) Common warnings</a>
<li><a href="#J">Annex J (informative) Portability issues</a>
<ul>
<li><a href="#K.3.9.1"> K.3.9.1 Formatted wide character input/output functions</a>
<li><a href="#K.3.9.2"> K.3.9.2 General wide string utilities</a>
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<li><a href="#K.3.9.3"> K.3.9.3 Extended multibyte/wide character conversion utilities</a>
</ul>
</ul>
</ul>
<li><a href="#Bibliography">Bibliography</a>
<li><a href="#Index">Index</a>
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</ul>
<a name="Foreword" href="#Foreword"><h2>Foreword</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
ISO (the International Organization for Standardization) and IEC (the International
Electrotechnical Commission) form the specialized system for worldwide
standardization. National bodies that are member of ISO or IEC participate in the
technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also
take part in the work.
-<p><!--para 2-->
+<p><!--para 2 -->
International Standards are drafted in accordance with the rules given in the ISO/IEC
Directives, Part 2. This International Standard was drafted in accordance with the fifth
edition (2004).
-<p><!--para 3-->
+<p><!--para 3 -->
In the field of information technology, ISO and IEC have established a joint technical
committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical
committee are circulated to national bodies for voting. Publication as an International
Standard requires approval by at least 75% of the national bodies casting a vote.
-<p><!--para 4-->
+<p><!--para 4 -->
Attention is drawn to the possibility that some of the elements of this document may be
the subject of patent rights. ISO and IEC shall not be held responsible for identifying any
or all such patent rights.
-<p><!--para 5-->
+<p><!--para 5 -->
This International Standard was prepared by Joint Technical Committee ISO/IEC JTC 1,
Information technology, Subcommittee SC 22, Programming languages, their
environments and system software interfaces. The Working Group responsible for this
std.org/JTC1/SC22/WG14/ containing additional information relevant to this
standard such as a Rationale for many of the decisions made during its preparation and a
log of Defect Reports and Responses.
-<p><!--para 6-->
+<p><!--para 6 -->
This third edition cancels and replaces the second edition, ISO/IEC 9899:1999, as
corrected by ISO/IEC 9899:1999/Cor 1:2001, ISO/IEC 9899:1999/Cor 2:2004, and
ISO/IEC 9899:1999/Cor 3:2007. Major changes from the previous edition include:
<li> Unicode characters and strings (<a href="#7.27"><uchar.h></a>) (originally specified in
ISO/IEC TR 19769:2004)
<li> type-generic expressions
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+<!--page 14 -->
<li> static assertions
<li> anonymous structures and unions
<li> no-return functions
ISO/IEC TR 24731-1:2007)
<li> (conditional) support for analyzability
</ul>
-<p><!--para 7-->
+<p><!--para 7 -->
Major changes in the second edition included:
<ul>
<li> restricted character set support via digraphs and <a href="#7.9"><iso646.h></a> (originally specified
<li> extended identifiers
<li> hexadecimal floating-point constants and %a and %A printf/scanf conversion
specifiers
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<li> compound literals
<li> designated initializers
<li> // comments
<li> va_copy macro
<li> additional strftime conversion specifiers
<li> LIA compatibility annex
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+<!--page 16 -->
<li> deprecate ungetc at the beginning of a binary file
<li> remove deprecation of aliased array parameters
<li> conversion of array to pointer not limited to lvalues
<li> return without expression not permitted in function that returns a value (and vice
versa)
</ul>
-<p><!--para 8-->
+<p><!--para 8 -->
Annexes D, F, G, K, and L form a normative part of this standard; annexes A, B, C, E, H, *
I, J, the bibliography, and the index are for information only. In accordance with Part 2 of
the ISO/IEC Directives, this foreword, the introduction, notes, footnotes, and examples
are also for information only.
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<a name="Introduction" href="#Introduction"><h2>Introduction</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
With the introduction of new devices and extended character sets, new features may be
added to this International Standard. Subclauses in the language and library clauses warn
implementors and programmers of usages which, though valid in themselves, may
conflict with future additions.
-<p><!--para 2-->
+<p><!--para 2 -->
Certain features are obsolescent, which means that they may be considered for
withdrawal in future revisions of this International Standard. They are retained because
of their widespread use, but their use in new implementations (for implementation
features) or new programs (for language [<a href="#6.11">6.11</a>] or library features [<a href="#7.30">7.30</a>]) is discouraged.
-<p><!--para 3-->
+<p><!--para 3 -->
This International Standard is divided into four major subdivisions:
<ul>
<li> preliminary elements (clauses 1-4);
<li> the language syntax, constraints, and semantics (clause 6);
<li> the library facilities (clause 7).
</ul>
-<p><!--para 4-->
+<p><!--para 4 -->
Examples are provided to illustrate possible forms of the constructions described.
Footnotes are provided to emphasize consequences of the rules described in that
subclause or elsewhere in this International Standard. References are used to refer to
implementors. Annexes provide additional information and summarize the information
contained in this International Standard. A bibliography lists documents that were
referred to during the preparation of the standard.
-<p><!--para 5-->
+<p><!--para 5 -->
The language clause (clause 6) is derived from ''The C Reference Manual''.
-<p><!--para 6-->
+<p><!--para 6 -->
The library clause (clause 7) is based on the 1984 /usr/group Standard.
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<h1>Programming languages -- C</h1>
<a name="1" href="#1"><h2>1. Scope</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This International Standard specifies the form and establishes the interpretation of
programs written in the C programming language.<sup><a href="#note1"><b>1)</b></a></sup> It specifies
<ul>
<li> the representation of output data produced by C programs;
<li> the restrictions and limits imposed by a conforming implementation of C.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
This International Standard does not specify
<ul>
<li> the mechanism by which C programs are transformed for use by a data-processing
conforming implementation.
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</ul>
<h6>footnotes</h6>
</small>
<a name="2" href="#2"><h2>2. Normative references</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
-<p><!--para 2-->
+<p><!--para 2 -->
ISO 31-11:1992, Quantities and units -- Part 11: Mathematical signs and symbols for
use in the physical sciences and technology.
-<p><!--para 3-->
+<p><!--para 3 -->
ISO/IEC 646, Information technology -- ISO 7-bit coded character set for information
interchange.
-<p><!--para 4-->
+<p><!--para 4 -->
ISO/IEC 2382-1:1993, Information technology -- Vocabulary -- Part 1: Fundamental
terms.
-<p><!--para 5-->
+<p><!--para 5 -->
ISO 4217, Codes for the representation of currencies and funds.
-<p><!--para 6-->
+<p><!--para 6 -->
ISO 8601, Data elements and interchange formats -- Information interchange --
Representation of dates and times.
-<p><!--para 7-->
+<p><!--para 7 -->
ISO/IEC 10646 (all parts), Information technology -- Universal Multiple-Octet Coded
Character Set (UCS).
-<p><!--para 8-->
+<p><!--para 8 -->
IEC 60559:1989, Binary floating-point arithmetic for microprocessor systems (previously
designated IEC 559:1989).
-<!--page 21 indent 4-->
+<!--page 21 -->
<a name="3" href="#3"><h2>3. Terms, definitions, and symbols</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
For the purposes of this International Standard, the following definitions apply. Other
terms are defined where they appear in italic type or on the left side of a syntax rule.
Terms explicitly defined in this International Standard are not to be presumed to refer
defined in this International Standard are to be interpreted according to ISO 31-11.
<a name="3.1" href="#3.1"><h3>3.1</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
access
<execution-time action> to read or modify the value of an object
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE 1 Where only one of these two actions is meant, ''read'' or ''modify'' is used.
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE 2 ''Modify'' includes the case where the new value being stored is the same as the previous value.
-<p><!--para 4-->
+<p><!--para 4 -->
NOTE 3 Expressions that are not evaluated do not access objects.
<a name="3.2" href="#3.2"><h3>3.2</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
alignment
requirement that objects of a particular type be located on storage boundaries with
addresses that are particular multiples of a byte address
<a name="3.3" href="#3.3"><h3>3.3</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
argument
actual argument
actual parameter (deprecated)
by the parentheses in a function-like macro invocation
<a name="3.4" href="#3.4"><h3>3.4</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
behavior
external appearance or action
<a name="3.4.1" href="#3.4.1"><h4>3.4.1</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
implementation-defined behavior
unspecified behavior where each implementation documents how the choice is made
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE An example of implementation-defined behavior is the propagation of the high-order bit
when a signed integer is shifted right.
<a name="3.4.2" href="#3.4.2"><h4>3.4.2</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
locale-specific behavior
behavior that depends on local conventions of nationality, culture, and language that each
implementation documents
-<!--page 22 indent 4-->
-<p><!--para 2-->
+<!--page 22 -->
+<p><!--para 2 -->
EXAMPLE An example of locale-specific behavior is whether the islower function returns true for
characters other than the 26 lowercase Latin letters.
<a name="3.4.3" href="#3.4.3"><h4>3.4.3</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
undefined behavior
behavior, upon use of a nonportable or erroneous program construct or of erroneous data,
for which this International Standard imposes no requirements
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE Possible undefined behavior ranges from ignoring the situation completely with unpredictable
results, to behaving during translation or program execution in a documented manner characteristic of the
environment (with or without the issuance of a diagnostic message), to terminating a translation or
execution (with the issuance of a diagnostic message).
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE An example of undefined behavior is the behavior on integer overflow.
<a name="3.4.4" href="#3.4.4"><h4>3.4.4</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
unspecified behavior
use of an unspecified value, or other behavior where this International Standard provides
two or more possibilities and imposes no further requirements on which is chosen in any
instance
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE An example of unspecified behavior is the order in which the arguments to a function are
evaluated.
<a name="3.5" href="#3.5"><h3>3.5</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
bit
unit of data storage in the execution environment large enough to hold an object that may
have one of two values
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE It need not be possible to express the address of each individual bit of an object.
<a name="3.6" href="#3.6"><h3>3.6</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
byte
addressable unit of data storage large enough to hold any member of the basic character
set of the execution environment
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE 1 It is possible to express the address of each individual byte of an object uniquely.
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE 2 A byte is composed of a contiguous sequence of bits, the number of which is implementation-
defined. The least significant bit is called the low-order bit; the most significant bit is called the high-order
bit.
<a name="3.7" href="#3.7"><h3>3.7</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
character
<abstract> member of a set of elements used for the organization, control, or
representation of data
<a name="3.7.1" href="#3.7.1"><h4>3.7.1</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
character
single-byte character
<C> bit representation that fits in a byte
-<!--page 23 indent 4-->
+<!--page 23 -->
<a name="3.7.2" href="#3.7.2"><h4>3.7.2</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
multibyte character
sequence of one or more bytes representing a member of the extended character set of
either the source or the execution environment
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE The extended character set is a superset of the basic character set.
<a name="3.7.3" href="#3.7.3"><h4>3.7.3</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
wide character
bit representation that fits in an object of type wchar_t, capable of representing any
character in the current locale
<a name="3.8" href="#3.8"><h3>3.8</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
constraint
restriction, either syntactic or semantic, by which the exposition of language elements is
to be interpreted
<a name="3.9" href="#3.9"><h3>3.9</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
correctly rounded result
representation in the result format that is nearest in value, subject to the current rounding
mode, to what the result would be given unlimited range and precision
<a name="3.10" href="#3.10"><h3>3.10</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
diagnostic message
message belonging to an implementation-defined subset of the implementation's message
output
<a name="3.11" href="#3.11"><h3>3.11</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
forward reference
reference to a later subclause of this International Standard that contains additional
information relevant to this subclause
<a name="3.12" href="#3.12"><h3>3.12</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
implementation
particular set of software, running in a particular translation environment under particular
control options, that performs translation of programs for, and supports execution of
functions in, a particular execution environment
<a name="3.13" href="#3.13"><h3>3.13</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
implementation limit
restriction imposed upon programs by the implementation
<a name="3.14" href="#3.14"><h3>3.14</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
memory location
either an object of scalar type, or a maximal sequence of adjacent bit-fields all having
nonzero width
-<!--page 24 indent 4-->
-<p><!--para 2-->
+<!--page 24 -->
+<p><!--para 2 -->
NOTE 1 Two threads of execution can update and access separate memory locations without interfering
with each other.
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE 2 A bit-field and an adjacent non-bit-field member are in separate memory locations. The same
applies to two bit-fields, if one is declared inside a nested structure declaration and the other is not, or if the
two are separated by a zero-length bit-field declaration, or if they are separated by a non-bit-field member
members declared between them are also (non-zero-length) bit-fields, no matter what the sizes of those
intervening bit-fields happen to be.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE A structure declared as
<pre>
struct {
<a name="3.15" href="#3.15"><h3>3.15</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
object
region of data storage in the execution environment, the contents of which can represent
values
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE When referenced, an object may be interpreted as having a particular type; see <a href="#6.3.2.1">6.3.2.1</a>.
<a name="3.16" href="#3.16"><h3>3.16</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
parameter
formal parameter
formal argument (deprecated)
parentheses immediately following the macro name in a function-like macro definition
<a name="3.17" href="#3.17"><h3>3.17</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
recommended practice
specification that is strongly recommended as being in keeping with the intent of the
standard, but that may be impractical for some implementations
<a name="3.18" href="#3.18"><h3>3.18</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
runtime-constraint
requirement on a program when calling a library function
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE 1 Despite the similar terms, a runtime-constraint is not a kind of constraint as defined by <a href="#3.8">3.8</a>, and
need not be diagnosed at translation time.
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE 2 Implementations that support the extensions in <a href="#K">annex K</a> are required to verify that the runtime-
constraints for a library function are not violated by the program; see <a href="#K.3.1.4">K.3.1.4</a>.
-<!--page 25 indent 4-->
+<!--page 25 -->
<a name="3.19" href="#3.19"><h3>3.19</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
value
precise meaning of the contents of an object when interpreted as having a specific type
<a name="3.19.1" href="#3.19.1"><h4>3.19.1</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
implementation-defined value
unspecified value where each implementation documents how the choice is made
<a name="3.19.2" href="#3.19.2"><h4>3.19.2</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
indeterminate value
either an unspecified value or a trap representation
<a name="3.19.3" href="#3.19.3"><h4>3.19.3</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
unspecified value
valid value of the relevant type where this International Standard imposes no
requirements on which value is chosen in any instance
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE An unspecified value cannot be a trap representation.
<a name="3.19.4" href="#3.19.4"><h4>3.19.4</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
trap representation
an object representation that need not represent a value of the object type
<a name="3.19.5" href="#3.19.5"><h4>3.19.5</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
perform a trap
interrupt execution of the program such that no further operations are performed
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE In this International Standard, when the word ''trap'' is not immediately followed by
''representation'', this is the intended usage.<sup><a href="#note2"><b>2)</b></a></sup>
</small>
<a name="3.20" href="#3.20"><h3>3.20</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
[^ x^]
ceiling of x: the least integer greater than or equal to x
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE [^2.4^] is 3, [^-2.4^] is -2.
<a name="3.21" href="#3.21"><h3>3.21</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
[_ x_]
floor of x: the greatest integer less than or equal to x
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE [_2.4_] is 2, [_-2.4_] is -3.
-<!--page 26 indent 4-->
+<!--page 26 -->
<a name="4" href="#4"><h2>4. Conformance</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In this International Standard, ''shall'' is to be interpreted as a requirement on an
implementation or on a program; conversely, ''shall not'' is to be interpreted as a
prohibition.
-<p><!--para 2-->
+<p><!--para 2 -->
If a ''shall'' or ''shall not'' requirement that appears outside of a constraint or runtime-
constraint is violated, the behavior is undefined. Undefined behavior is otherwise
indicated in this International Standard by the words ''undefined behavior'' or by the
omission of any explicit definition of behavior. There is no difference in emphasis among
these three; they all describe ''behavior that is undefined''.
-<p><!--para 3-->
+<p><!--para 3 -->
A program that is correct in all other aspects, operating on correct data, containing
unspecified behavior shall be a correct program and act in accordance with <a href="#5.1.2.3">5.1.2.3</a>.
-<p><!--para 4-->
+<p><!--para 4 -->
The implementation shall not successfully translate a preprocessing translation unit
containing a #error preprocessing directive unless it is part of a group skipped by
conditional inclusion.
-<p><!--para 5-->
+<p><!--para 5 -->
A strictly conforming program shall use only those features of the language and library
specified in this International Standard.<sup><a href="#note3"><b>3)</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.
-<p><!--para 6-->
+<p><!--para 6 -->
The two forms of conforming implementation are hosted and freestanding. A conforming
hosted implementation shall accept any strictly conforming program. A conforming
freestanding implementation shall accept any strictly conforming program that does not
-<!--page 27 indent 4-->
-<p><!--para 7-->
+<!--page 27 -->
+<p><!--para 7 -->
A conforming program is one that is acceptable to a conforming implementation.<sup><a href="#note5"><b>5)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
An implementation shall be accompanied by a document that defines all implementation-
defined and locale-specific characteristics and all extensions.
<p><b> Forward references</b>: conditional inclusion (<a href="#6.10.1">6.10.1</a>), error directive (<a href="#6.10.5">6.10.5</a>),
-<!--page 28 indent 4-->
+<!--page 28 -->
<h6>footnotes</h6>
<p><small><a name="note3" href="#note3">3)</a> A strictly conforming program can use conditional features (see <a href="#6.10.8.3">6.10.8.3</a>) provided the use is guarded
</small>
<a name="5" href="#5"><h2>5. Environment</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An implementation translates C source files and executes C programs in two data-
processing-system environments, which will be called the translation environment and
the execution environment in this International Standard. Their characteristics define and
<a name="5.1.1" href="#5.1.1"><h4>5.1.1 Translation environment</h4></a>
<a name="5.1.1.1" href="#5.1.1.1"><h5>5.1.1.1 Program structure</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A C program need not all be translated at the same time. The text of the program is kept
in units called source files, (or preprocessing files) in this International Standard. A
source file together with all the headers and source files included via the preprocessing
preprocessing directives (<a href="#6.10">6.10</a>).
<a name="5.1.1.2" href="#5.1.1.2"><h5>5.1.1.2 Translation phases</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The precedence among the syntax rules of translation is specified by the following
phases.<sup><a href="#note6"><b>6)</b></a></sup>
<ol>
-<!--page 29 indent 0-->
+<!--page 29 -->
<li> Each instance of a backslash character (\) immediately followed by a new-line
character is deleted, splicing physical source lines to form logical source lines.
Only the last backslash on any physical source line shall be eligible for being part
-<!--page 30 indent 4-->
+<!--page 30 -->
<h6>footnotes</h6>
<p><small><a name="note6" href="#note6">6)</a> Implementations shall behave as if these separate phases occur, even though many are typically folded
</small>
<a name="5.1.1.3" href="#5.1.1.3"><h5>5.1.1.3 Diagnostics</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A conforming implementation shall produce at least one diagnostic message (identified in
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.<sup><a href="#note9"><b>9)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE An implementation shall issue a diagnostic for the translation unit:
<pre>
char i;
</small>
<a name="5.1.2" href="#5.1.2"><h4>5.1.2 Execution environments</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Two execution environments are defined: freestanding and hosted. In both cases,
program startup occurs when a designated C function is called by the execution
environment. All objects with static storage duration shall be initialized (set to their
<p><b> Forward references</b>: storage durations of objects (<a href="#6.2.4">6.2.4</a>), initialization (<a href="#6.7.9">6.7.9</a>).
<a name="5.1.2.1" href="#5.1.2.1"><h5>5.1.2.1 Freestanding environment</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In a freestanding environment (in which C program execution may take place without any
benefit of an operating system), the name and type of the function called at program
startup are implementation-defined. Any library facilities available to a freestanding
program, other than the minimal set required by clause 4, are implementation-defined.
-<p><!--para 2-->
+<p><!--para 2 -->
The effect of program termination in a freestanding environment is implementation-
defined.
<a name="5.1.2.2" href="#5.1.2.2"><h5>5.1.2.2 Hosted environment</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A hosted environment need not be provided, but shall conform to the following
specifications if present.
-<!--page 31 indent 4-->
+<!--page 31 -->
<a name="5.1.2.2.1" href="#5.1.2.2.1"><h5>5.1.2.2.1 Program startup</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The function called at program startup is named main. The implementation declares no
prototype for this function. It shall be defined with a return type of int and with no
parameters:
<pre>
int main(int argc, char *argv[]) { /* ... */ }</pre>
or equivalent;<sup><a href="#note10"><b>10)</b></a></sup> or in some other implementation-defined manner.
-<p><!--para 2-->
+<p><!--para 2 -->
If they are declared, the parameters to the main function shall obey the following
constraints:
<ul>
</small>
<a name="5.1.2.2.2" href="#5.1.2.2.2"><h5>5.1.2.2.2 Program execution</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In a hosted environment, a program may use all the functions, macros, type definitions,
and objects described in the library clause (clause 7).
-<!--page 32 indent 4-->
+<!--page 32 -->
<a name="5.1.2.2.3" href="#5.1.2.2.3"><h5>5.1.2.2.3 Program termination</h5></a>
-<p><!--para 1-->
+<p><!--para 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;<sup><a href="#note11"><b>11)</b></a></sup> reaching the } that terminates the
</small>
<a name="5.1.2.3" href="#5.1.2.3"><h5>5.1.2.3 Program execution</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The semantic descriptions in this International Standard describe the behavior of an
abstract machine in which issues of optimization are irrelevant.
-<p><!--para 2-->
+<p><!--para 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,<sup><a href="#note12"><b>12)</b></a></sup> which are changes in the state of
the execution environment. Evaluation of an expression in general includes both value
computations and initiation of side effects. Value computation for an lvalue expression
includes determining the identity of the designated object.
-<p><!--para 3-->
+<p><!--para 3 -->
Sequenced before is an asymmetric, transitive, pair-wise relation between evaluations
executed by a single thread, which induces a partial order among those evaluations.
Given any two evaluations A and B, if A is sequenced before B, then the execution of A
between the evaluation of expressions A and B implies that every value computation and
side effect associated with A is sequenced before every value computation and side effect
associated with B. (A summary of the sequence points is given in <a href="#C">annex C</a>.)
-<p><!--para 4-->
+<p><!--para 4 -->
In the abstract machine, all expressions are evaluated as specified by the semantics. An
actual implementation need not evaluate part of an expression if it can deduce that its
value is not used and that no needed side effects are produced (including any caused by
-<!--page 33 indent 5-->
+<!--page 33 -->
calling a function or accessing a volatile object).
-<p><!--para 5-->
+<p><!--para 5 -->
When the processing of the abstract machine is interrupted by receipt of a signal, the
values of objects that are neither lock-free atomic objects nor of type volatile
sig_atomic_t are unspecified, and the value of any object that is modified by the
handler that is neither a lock-free atomic object nor of type volatile
sig_atomic_t becomes undefined.
-<p><!--para 6-->
+<p><!--para 6 -->
The least requirements on a conforming implementation are:
<ul>
<li> Accesses to volatile objects are evaluated strictly according to the rules of the abstract
a program waiting for input.
</ul>
This is the observable behavior of the program.
-<p><!--para 7-->
+<p><!--para 7 -->
What constitutes an interactive device is implementation-defined.
-<p><!--para 8-->
+<p><!--para 8 -->
More stringent correspondences between abstract and actual semantics may be defined by
each implementation.
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 1 An implementation might define a one-to-one correspondence between abstract and actual
semantics: at every sequence point, the values of the actual objects would agree with those specified by the
abstract semantics. The keyword volatile would then be redundant.
-<p><!--para 10-->
+<p><!--para 10 -->
Alternatively, an implementation might perform various optimizations within each translation unit, such
that the actual semantics would agree with the abstract semantics only when making function calls across
translation unit boundaries. In such an implementation, at the time of each function entry and function
would require explicit specification of volatile storage, as well as other implementation-defined
restrictions.
-<p><!--para 11-->
+<p><!--para 11 -->
EXAMPLE 2 In executing the fragment
<pre>
char c1, c2;
and then add the two ints and truncate the sum. Provided the addition of two chars can be done without
overflow, or with overflow wrapping silently to produce the correct result, the actual execution need only
produce the same result, possibly omitting the promotions.
-<!--page 34 indent 5-->
-<p><!--para 12-->
+<!--page 34 -->
+<p><!--para 12 -->
EXAMPLE 3 Similarly, in the fragment
<pre>
float f1, f2;
that the result would be the same as if it were executed using double-precision arithmetic (for example, if d
were replaced by the constant 2.0, which has type double).
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 4 Implementations employing wide registers have to take care to honor appropriate
semantics. Values are independent of whether they are represented in a register or in memory. For
example, an implicit spilling of a register is not permitted to alter the value. Also, an explicit store and load
d2 = (float) expression;</pre>
the values assigned to d1 and d2 are required to have been converted to float.
-<p><!--para 14-->
+<p><!--para 14 -->
EXAMPLE 5 Rearrangement for floating-point expressions is often restricted because of limitations in
precision as well as range. The implementation cannot generally apply the mathematical associative rules
for addition or multiplication, nor the distributive rule, because of roundoff error, even in the absence of
z = x + x * y; // not equivalent to z = x * (1.0 + y);
y = x / 5.0; // not equivalent to y = x * 0.2;</pre>
-<p><!--para 15-->
+<p><!--para 15 -->
EXAMPLE 6 To illustrate the grouping behavior of expressions, in the following fragment
<pre>
int a, b;
a = ((a + b) + 32765);</pre>
since if the values for a and b were, respectively, -32754 and -15, the sum a + b would produce a trap
while the original expression would not; nor can the expression be rewritten either as
-<!--page 35 indent 5-->
+<!--page 35 -->
<pre>
a = ((a + 32765) + b);</pre>
or
above expression statement can be rewritten by the implementation in any of the above ways because the
same result will occur.
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE 7 The grouping of an expression does not completely determine its evaluation. In the
following fragment
<pre>
</small>
<a name="5.1.2.4" href="#5.1.2.4"><h5>5.1.2.4 Multi-threaded executions and data races</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Under a hosted implementation, a program can have more than one thread of execution
(or thread) running concurrently. The execution of each thread proceeds as defined by
the remainder of this standard. The execution of the entire program consists of an
execution of all of its threads.<sup><a href="#note14"><b>14)</b></a></sup> Under a freestanding implementation, it is
implementation-defined whether a program can have more than one thread of execution.
-<p><!--para 2-->
+<p><!--para 2 -->
The value of an object visible to a thread T at a particular point is the initial value of the
object, a value stored in the object by T , or a value stored in the object by another thread,
according to the rules below.
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE 1 In some cases, there may instead be undefined behavior. Much of this section is motivated by
the desire to support atomic operations with explicit and detailed visibility constraints. However, it also
implicitly supports a simpler view for more restricted programs.
-<p><!--para 4-->
+<p><!--para 4 -->
Two expression evaluations conflict if one of them modifies a memory location and the
other one reads or modifies the same memory location.
-<!--page 36 indent 5-->
-<p><!--para 5-->
+<!--page 36 -->
+<p><!--para 5 -->
The library defines a number of atomic operations (<a href="#7.17">7.17</a>) and operations on mutexes
(<a href="#7.25.4">7.25.4</a>) that are specially identified as synchronization operations. These operations play
a special role in making assignments in one thread visible to another. A synchronization
either an acquire fence, a release fence, or both an acquire and release fence. In addition,
there are relaxed atomic operations, which are not synchronization operations, and
atomic read-modify-write operations, which have special characteristics.
-<p><!--para 6-->
+<p><!--para 6 -->
NOTE 2 For example, a call that acquires a mutex will perform an acquire operation on the locations
composing the mutex. Correspondingly, a call that releases the same mutex will perform a release
operation on those same locations. Informally, performing a release operation on A forces prior side effects
operation on A. We do not include relaxed atomic operations as synchronization operations although, like
synchronization operations, they cannot contribute to data races.
-<p><!--para 7-->
+<p><!--para 7 -->
All modifications to a particular atomic object M occur in some particular total order,
called the modification order of M. If A and B are modifications of an atomic object M,
and A happens before B, then A shall precede B in the modification order of M, which is
defined below.
-<p><!--para 8-->
+<p><!--para 8 -->
NOTE 3 This states that the modification orders must respect the ''happens before'' relation.
-<p><!--para 9-->
+<p><!--para 9 -->
NOTE 4 There is a separate order for each atomic object. There is no requirement that these can be
combined into a single total order for all objects. In general this will be impossible since different threads
may observe modifications to different variables in inconsistent orders.
-<p><!--para 10-->
+<p><!--para 10 -->
A release sequence on an atomic object M is a maximal contiguous sub-sequence of side
effects in the modification order of M, where the first operation is a release and every
subsequent operation either is performed by the same thread that performed the release or
is an atomic read-modify-write operation.
-<p><!--para 11-->
+<p><!--para 11 -->
Certain library calls synchronize with other library calls performed by another thread. In
particular, an atomic operation A that performs a release operation on an object M
synchronizes with an atomic operation B that performs an acquire operation on M and
reads a value written by any side effect in the release sequence headed by A.
-<p><!--para 12-->
+<p><!--para 12 -->
NOTE 5 Except in the specified cases, reading a later value does not necessarily ensure visibility as
described below. Such a requirement would sometimes interfere with efficient implementation.
-<p><!--para 13-->
+<p><!--para 13 -->
NOTE 6 The specifications of the synchronization operations define when one reads the value written by
another. For atomic variables, the definition is clear. All operations on a given mutex occur in a single total
order. Each mutex acquisition ''reads the value written'' by the last mutex release.
-<p><!--para 14-->
+<p><!--para 14 -->
An evaluation A carries a dependency <sup><a href="#note15"><b>15)</b></a></sup> to an evaluation B if:
-<!--page 37 indent 5-->
+<!--page 37 -->
<ul>
<li> the value of A is used as an operand of B, unless:
<ul>
is sequenced before B, or
<li> for some evaluation X, A carries a dependency to X and X carries a dependency to B.
</ul>
-<p><!--para 15-->
+<p><!--para 15 -->
An evaluation A is dependency-ordered before<sup><a href="#note16"><b>16)</b></a></sup> an evaluation B if:
<ul>
<li> A performs a release operation on an atomic object M, and B performs a consume
<li> for some evaluation X, A is dependency-ordered before X and X carries a
dependency to B.
</ul>
-<p><!--para 16-->
+<p><!--para 16 -->
An evaluation A inter-thread happens before an evaluation B if A synchronizes with B, A
is dependency-ordered before B, or, for some evaluation X:
<ul>
<li> A is sequenced before X and X inter-thread happens before B, or
<li> A inter-thread happens before X and X inter-thread happens before B.
</ul>
-<p><!--para 17-->
+<p><!--para 17 -->
NOTE 7 The ''inter-thread happens before'' relation describes arbitrary concatenations of ''sequenced
before'', ''synchronizes with'', and ''dependency-ordered before'' relationships, with two exceptions. The
first exception is that a concatenation is not permitted to end with ''dependency-ordered before'' followed
transitively closed and (2) the ''happens before'' relation, defined below, provides for relationships
consisting entirely of ''sequenced before''.
-<p><!--para 18-->
+<p><!--para 18 -->
An evaluation A happens before an evaluation B if A is sequenced before B or A inter-
thread happens before B.
-<!--page 38 indent 5-->
-<p><!--para 19-->
+<!--page 38 -->
+<p><!--para 19 -->
A visible side effect A on an object M with respect to a value computation B of M
satisfies the conditions:
<ul>
</ul>
The value of a non-atomic scalar object M, as determined by evaluation B, shall be the
value stored by the visible side effect A.
-<p><!--para 20-->
+<p><!--para 20 -->
NOTE 8 If there is ambiguity about which side effect to a non-atomic object is visible, then there is a data
race and the behavior is undefined.
-<p><!--para 21-->
+<p><!--para 21 -->
NOTE 9 This states that operations on ordinary variables are not visibly reordered. This is not actually
detectable without data races, but it is necessary to ensure that data races, as defined here, and with suitable
restrictions on the use of atomics, correspond to data races in a simple interleaved (sequentially consistent)
execution.
-<p><!--para 22-->
+<p><!--para 22 -->
The visible sequence of side effects on an atomic object M, with respect to a value
computation B of M, is a maximal contiguous sub-sequence of side effects in the
modification order of M, where the first side effect is visible with respect to B, and for
the value computed by A corresponds to the value stored by side effect X, then the value
computed by B shall either equal the value computed by A, or be the value stored by side
effect Y , where Y follows X in the modification order of M.
-<p><!--para 23-->
+<p><!--para 23 -->
NOTE 10 This effectively disallows compiler reordering of atomic operations to a single object, even if
both operations are ''relaxed'' loads. By doing so, we effectively make the ''cache coherence'' guarantee
provided by most hardware available to C atomic operations.
-<p><!--para 24-->
+<p><!--para 24 -->
NOTE 11 The visible sequence depends on the ''happens before'' relation, which in turn depends on the
values observed by loads of atomics, which we are restricting here. The intended reading is that there must
exist an association of atomic loads with modifications they observe that, together with suitably chosen
modification orders and the ''happens before'' relation derived as described above, satisfy the resulting
constraints as imposed here.
-<p><!--para 25-->
+<p><!--para 25 -->
The execution of a program contains a data race if it contains two conflicting actions in
different threads, at least one of which is not atomic, and neither happens before the
other. Any such data race results in undefined behavior.
-<p><!--para 26-->
+<p><!--para 26 -->
NOTE 12 It can be shown that programs that correctly use simple mutexes and
memory_order_seq_cst operations to prevent all data races, and use no other synchronization
operations, behave as though the operations executed by their constituent threads were simply interleaved,
race-free programs cannot observe most program transformations that do not change single-threaded
program semantics. In fact, most single-threaded program transformations continue to be allowed, since
any program that behaves differently as a result must contain undefined behavior.
-<!--page 39 indent 5-->
-<p><!--para 27-->
+<!--page 39 -->
+<p><!--para 27 -->
NOTE 13 Compiler transformations that introduce assignments to a potentially shared memory location
that would not be modified by the abstract machine are generally precluded by this standard, since such an
assignment might overwrite another assignment by a different thread in cases in which an abstract machine
reordering of atomic loads in cases in which the atomics in question may alias, since this may violate the
"visible sequence" rules.
-<p><!--para 28-->
+<p><!--para 28 -->
NOTE 14 Transformations that introduce a speculative read of a potentially shared memory location may
not preserve the semantics of the program as defined in this standard, since they potentially introduce a data
race. However, they are typically valid in the context of an optimizing compiler that targets a specific
machine with well-defined semantics for data races. They would be invalid for a hypothetical machine that
is not tolerant of races or provides hardware race detection.
-<!--page 40 indent 4-->
+<!--page 40 -->
<h6>footnotes</h6>
<p><small><a name="note14" href="#note14">14)</a> The execution can usually be viewed as an interleaving of all of the threads. However, some kinds of
<a name="5.2" href="#5.2"><h3>5.2 Environmental considerations</h3></a>
<a name="5.2.1" href="#5.2.1"><h4>5.2.1 Character sets</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Two sets of characters and their associated collating sequences shall be defined: the set in
which source files are written (the source character set), and the set interpreted in the
execution environment (the execution character set). Each set is further divided into a
locale-specific members (which are not members of the basic character set) called
extended characters. The combined set is also called the extended character set. The
values of the members of the execution character set are implementation-defined.
-<p><!--para 2-->
+<p><!--para 2 -->
In a character constant or string literal, members of the execution character set shall be
represented by corresponding members of the source character set or by escape
sequences consisting of the backslash \ followed by one or more characters. A byte with
all bits set to 0, called the null character, shall exist in the basic execution character set; it
is used to terminate a character string.
-<p><!--para 3-->
+<p><!--para 3 -->
Both the basic source and basic execution character sets shall have the following
members: the 26 uppercase letters of the Latin alphabet
<pre>
control characters representing alert, backspace, carriage return, and new line. If any
other characters are encountered in a source file (except in an identifier, a character
constant, a string literal, a header name, a comment, or a preprocessing token that is never
-<!--page 41 indent 4-->
+<!--page 41 -->
converted to a token), the behavior is undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
A letter is an uppercase letter or a lowercase letter as defined above; in this International
Standard the term does not include other characters that are letters in other alphabets.
-<p><!--para 5-->
+<p><!--para 5 -->
The universal character name construct provides a way to name other characters.
<p><b> Forward references</b>: universal character names (<a href="#6.4.3">6.4.3</a>), character constants (<a href="#6.4.4.4">6.4.4.4</a>),
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"><h5>5.2.1.1 Trigraph sequences</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Before any other processing takes place, each occurrence of one of the following
sequences of three characters (called trigraph sequences<sup><a href="#note17"><b>17)</b></a></sup>) is replaced with the
corresponding single character.
??/ \ ??< { ??- ~</pre>
No other trigraph sequences exist. Each ? that does not begin one of the trigraphs listed
above is not changed.
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE 1
<pre>
??=define arraycheck(a, b) a??(b??) ??!??! b??(a??)</pre>
<pre>
#define arraycheck(a, b) a[b] || b[a]</pre>
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE 2 The following source line
<pre>
printf("Eh???/n");</pre>
</small>
<a name="5.2.1.2" href="#5.2.1.2"><h5>5.2.1.2 Multibyte characters</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The source character set may contain multibyte characters, used to represent members of
the extended character set. The execution character set may also contain multibyte
characters, which need not have the same encoding as for the source character set. For
<li> The presence, meaning, and representation of any additional members is locale-
specific.
-<!--page 42 indent 4-->
+<!--page 42 -->
<li> A multibyte character set may have a state-dependent encoding, wherein each
sequence of multibyte characters begins in an initial shift state and enters other
locale-specific shift states when specific multibyte characters are encountered in the
<li> A byte with all bits zero shall be interpreted as a null character independent of shift
state. Such a byte shall not occur as part of any other multibyte character.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
For source files, the following shall hold:
<ul>
<li> An identifier, comment, string literal, character constant, or header name shall begin
</ul>
<a name="5.2.2" href="#5.2.2"><h4>5.2.2 Character display semantics</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The active position is that location on a display device where the next character output by
the fputc function would appear. The intent of writing a printing character (as defined
by the isprint function) to a display device is to display a graphic representation of
position on the current line. The direction of writing is locale-specific. If the active
position is at the final position of a line (if there is one), the behavior of the display device
is unspecified.
-<p><!--para 2-->
+<p><!--para 2 -->
Alphabetic escape sequences representing nongraphic characters in the execution
character set are intended to produce actions on display devices as follows:
\a (alert) Produces an audible or visible alert without changing the active position.
on the current line. If the active position is at or past the last defined horizontal
tabulation position, the behavior of the display device is unspecified.</pre>
\v (vertical tab) Moves the active position to the initial position of the next vertical
-<!--page 43 indent 4-->
-<p><!--para 3-->
+<!--page 43 -->
+<p><!--para 3 -->
<pre>
tabulation position. If the active position is at or past the last defined vertical
tabulation position, the behavior of the display device is unspecified.</pre>
<p><b> Forward references</b>: the isprint function (<a href="#7.4.1.8">7.4.1.8</a>), the fputc function (<a href="#7.21.7.3">7.21.7.3</a>).
<a name="5.2.3" href="#5.2.3"><h4>5.2.3 Signals and interrupts</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Functions shall be implemented such that they may be interrupted at any time by a signal,
or may be called by a signal handler, or both, with no alteration to earlier, but still active,
invocations' control flow (after the interruption), function return values, or objects with
per-invocation basis.
<a name="5.2.4" href="#5.2.4"><h4>5.2.4 Environmental limits</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Both the translation and execution environments constrain the implementation of
language translators and libraries. The following summarizes the language-related
environmental limits on a conforming implementation; the library-related limits are
discussed in clause 7.
<a name="5.2.4.1" href="#5.2.4.1"><h5>5.2.4.1 Translation limits</h5></a>
-<p><!--para 1-->
+<p><!--para 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:<sup><a href="#note18"><b>18)</b></a></sup>
<ul>
specifying a short identifier of 0000FFFF or less is considered 6 characters, each
-<!--page 44 indent 4-->
+<!--page 44 -->
<pre>
universal character name specifying a short identifier of 00010000 or more is
considered 10 characters, and each extended source character is considered the same
</small>
<a name="5.2.4.2" href="#5.2.4.2"><h5>5.2.4.2 Numerical limits</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An implementation is required to document all the limits specified in this subclause,
which are specified in the headers <a href="#7.10"><limits.h></a> and <a href="#7.7"><float.h></a>. Additional limits are
specified in <a href="#7.20"><stdint.h></a>.
<p><b> Forward references</b>: integer types <a href="#7.20"><stdint.h></a> (<a href="#7.20">7.20</a>).
<a name="5.2.4.2.1" href="#5.2.4.2.1"><h5>5.2.4.2.1 Sizes of integer types <limits.h></h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The values given below shall be replaced by constant expressions suitable for use in #if
preprocessing directives. Moreover, except for CHAR_BIT and MB_LEN_MAX, the
following shall be replaced by expressions that have the same type as would an
promotions. Their implementation-defined values shall be equal or greater in magnitude
-<!--page 45 indent 0-->
+<!--page 45 -->
(absolute value) to those shown, with the same sign.
<ul>
<li> number of bits for smallest object that is not a bit-field (byte)
LONG_MAX +2147483647 // 231 - 1
<li> maximum value for an object of type unsigned long int
ULONG_MAX 4294967295 // 232 - 1
-<!--page 46 indent 4-->
+<!--page 46 -->
<li> minimum value for an object of type long long int
LLONG_MIN -9223372036854775807 // -(263 - 1)
<li> maximum value for an object of type long long int
<li> maximum value for an object of type unsigned long long int
ULLONG_MAX 18446744073709551615 // 264 - 1
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
If the value of an object of type char is treated as a signed integer when used in an
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
</small>
<a name="5.2.4.2.2" href="#5.2.4.2.2"><h5>5.2.4.2.2 Characteristics of floating types <float.h></h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The characteristics of floating types are defined in terms of a model that describes a
representation of floating-point numbers and values that provide information about an
implementation's floating-point arithmetic.<sup><a href="#note21"><b>21)</b></a></sup> The following parameters are used to
define the model for each floating-point type:
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
s sign ((+-)1)
b base or radix of exponent representation (an integer > 1)
k=1
emin <= e <= emax</pre>
-<p><!--para 3-->
+<p><!--para 3 -->
In addition to normalized floating-point numbers ( f 1 > 0 if x != 0), floating types may be
able to contain other kinds of floating-point numbers, such as subnormal floating-point
numbers (x != 0, e = emin , f 1 = 0) and unnormalized floating-point numbers (x != 0,
signaling NaN generally raises a floating-point exception when occurring as an
-<!--page 47 indent 4-->
+<!--page 47 -->
arithmetic operand.<sup><a href="#note22"><b>22)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
An implementation may give zero and values that are not floating-point numbers (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 any requirement to set the sign shall be ignored.
-<p><!--para 5-->
+<p><!--para 5 -->
The minimum range of representable values for a floating type is the most negative finite
floating-point number representable in that type through the most positive finite floating-
point number representable in that type. In addition, if negative infinity is representable
in a type, the range of that type is extended to all negative real numbers; likewise, if
positive infinity is representable in a type, the range of that type is extended to all positive
real numbers.
-<p><!--para 6-->
+<p><!--para 6 -->
The accuracy of the floating-point operations (+, -, *, /) and of the library functions in
<a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> that return floating-point results is implementation-
defined, as is the accuracy of the conversion between floating-point internal
representations and string representations performed by the library functions in
<a href="#7.21"><stdio.h></a>, <a href="#7.22"><stdlib.h></a>, and <a href="#7.28"><wchar.h></a>. The implementation may state that the
accuracy is unknown.
-<p><!--para 7-->
+<p><!--para 7 -->
All integer values in the <a href="#7.7"><float.h></a> header, except FLT_ROUNDS, shall be constant
expressions suitable for use in #if preprocessing directives; all floating values shall be
constant expressions. All except DECIMAL_DIG, FLT_EVAL_METHOD, FLT_RADIX,
and FLT_ROUNDS have separate names for all three floating-point types. The floating-
point model representation is provided for all values except FLT_EVAL_METHOD and
FLT_ROUNDS.
-<p><!--para 8-->
+<p><!--para 8 -->
The rounding mode for floating-point addition is characterized by the implementation-
defined value of FLT_ROUNDS:<sup><a href="#note23"><b>23)</b></a></sup>
<pre>
behavior.
-<!--page 48 indent 5-->
-<p><!--para 9-->
+<!--page 48 -->
+<p><!--para 9 -->
Except for assignment and cast (which remove all extra range and precision), the values
yielded by operators with floating operands and values subject to the usual arithmetic
conversions and of floating constants are evaluated to a format whose range and precision
long double type.</pre>
All other negative values for FLT_EVAL_METHOD characterize implementation-defined
behavior.
-<p><!--para 10-->
+<p><!--para 10 -->
The presence or absence of subnormal numbers is characterized by the implementation-
defined values of FLT_HAS_SUBNORM, DBL_HAS_SUBNORM, and
LDBL_HAS_SUBNORM:
-<p><!--para 11-->
+<p><!--para 11 -->
<pre>
-1 indeterminable<sup><a href="#note25"><b>25)</b></a></sup>
0 absent<sup><a href="#note26"><b>26)</b></a></sup> (type does not support subnormal numbers)
-<!--page 49 indent 0-->
+<!--page 49 -->
<li> number of base-FLT_RADIX digits in the floating-point significand, p
FLT_MANT_DIG
DBL_MANT_DIG
FLT_MIN_EXP
DBL_MIN_EXP
LDBL_MIN_EXP
-<!--page 50 indent 5-->
+<!--page 50 -->
<li> minimum negative integer such that 10 raised to that power is in the range of
normalized floating-point numbers, [^log10 b emin -1 ^]
<pre>
<li> maximum integer such that 10 raised to that power is in the range of representable
finite floating-point numbers, [_log10 ((1 - b- p )b emax )_]
</ul>
-<p><!--para 12-->
+<p><!--para 12 -->
<pre>
FLT_MAX_10_EXP +37
DBL_MAX_10_EXP +37
<ul>
<li> maximum representable finite floating-point number, (1 - b- p )b emax
</ul>
-<p><!--para 13-->
+<p><!--para 13 -->
<pre>
FLT_MAX 1E+37
DBL_MAX 1E+37
DBL_EPSILON 1E-9
LDBL_EPSILON 1E-9</pre>
<li> minimum normalized positive floating-point number, b emin -1
-<!--page 51 indent 5-->
+<!--page 51 -->
<pre>
FLT_MIN 1E-37
DBL_MIN 1E-37
LDBL_TRUE_MIN 1E-37
</ul>
Recommended practice
-<p><!--para 14-->
+<p><!--para 14 -->
Conversion from (at least) double to decimal with DECIMAL_DIG digits and back
should be the identity function.
-<p><!--para 15-->
+<p><!--para 15 -->
EXAMPLE 1 The following describes an artificial floating-point representation that meets the minimum
requirements of this International Standard, and the appropriate values in a <a href="#7.7"><float.h></a> header for type
float:
FLT_MAX 3.40282347E+38F
FLT_MAX_10_EXP +38</pre>
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE 2 The following describes floating-point representations that also meet the requirements for
single-precision and double-precision numbers in IEC 60559,<sup><a href="#note28"><b>28)</b></a></sup> and the appropriate values in a
<a href="#7.7"><float.h></a> header for types float and double:
FLT_DECIMAL_DIG 9</pre>
-<!--page 52 indent 0-->
+<!--page 52 -->
<pre>
FLT_DIG 6
FLT_MIN_EXP -125
<a href="#7.3"><complex.h></a> (<a href="#7.3">7.3</a>), extended multibyte and wide character utilities <a href="#7.28"><wchar.h></a>
(<a href="#7.28">7.28</a>), floating-point environment <a href="#7.6"><fenv.h></a> (<a href="#7.6">7.6</a>), general utilities <a href="#7.22"><stdlib.h></a>
(<a href="#7.22">7.22</a>), input/output <a href="#7.21"><stdio.h></a> (<a href="#7.21">7.21</a>), mathematics <a href="#7.12"><math.h></a> (<a href="#7.12">7.12</a>).
-<!--page 53 indent 4-->
+<!--page 53 -->
<h6>footnotes</h6>
<p><small><a name="note21" href="#note21">21)</a> The floating-point model is intended to clarify the description of each floating-point characteristic and
<a name="6" href="#6"><h2>6. Language</h2></a>
<a name="6.1" href="#6.1"><h3>6.1 Notation</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In the syntax notation used in this clause, syntactic categories (nonterminals) are
indicated by italic type, and literal words and character set members (terminals) by bold
type. A colon (:) following a nonterminal introduces its definition. Alternative
<pre>
{ expressionopt }</pre>
indicates an optional expression enclosed in braces.
-<p><!--para 2-->
+<p><!--para 2 -->
When syntactic categories are referred to in the main text, they are not italicized and
words are separated by spaces instead of hyphens.
-<p><!--para 3-->
+<p><!--para 3 -->
A summary of the language syntax is given in <a href="#A">annex A</a>.
<a name="6.2" href="#6.2"><h3>6.2 Concepts</h3></a>
<a name="6.2.1" href="#6.2.1"><h4>6.2.1 Scopes of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An identifier can denote an object; a function; a tag or a member of a structure, union, or
enumeration; a typedef name; a label name; a macro name; or a macro parameter. The
same identifier can denote different entities at different points in the program. A member
parameters are not considered further here, because prior to the semantic phase of
program translation any occurrences of macro names in the source file are replaced by the
preprocessing token sequences that constitute their macro definitions.
-<p><!--para 2-->
+<p><!--para 2 -->
For each different entity that an identifier designates, the identifier is visible (i.e., can be
used) only within a region of program text called its scope. Different entities designated
by the same identifier either have different scopes, or are in different name spaces. There
are four kinds of scopes: function, file, block, and function prototype. (A function
prototype is a declaration of a function that declares the types of its parameters.)
-<p><!--para 3-->
+<p><!--para 3 -->
A label name is the only kind of identifier that has function scope. It can be used (in a
goto statement) anywhere in the function in which it appears, and is declared implicitly
by its syntactic appearance (followed by a : and a statement).
-<p><!--para 4-->
+<p><!--para 4 -->
Every other identifier has scope determined by the placement of its declaration (in a
declarator or type specifier). If the declarator or type specifier that declares the identifier
appears outside of any block or list of parameters, the identifier has file scope, which
declares the identifier appears inside a block or within the list of parameter declarations in
a function definition, the identifier has block scope, which terminates at the end of the
associated block. If the declarator or type specifier that declares the identifier appears
-<!--page 54 indent 4-->
+<!--page 54 -->
within the list of parameter declarations in a function prototype (not part of a function
definition), the identifier has function prototype scope, which terminates at the end of the
function declarator. If an identifier designates two different entities in the same name
strictly before the scope of the other entity (the outer scope). Within the inner scope, the
identifier designates the entity declared in the inner scope; the entity declared in the outer
scope is hidden (and not visible) within the inner scope.
-<p><!--para 5-->
+<p><!--para 5 -->
Unless explicitly stated otherwise, where this International Standard uses the term
''identifier'' to refer to some entity (as opposed to the syntactic construct), it refers to the
entity in the relevant name space whose declaration is visible at the point the identifier
occurs.
-<p><!--para 6-->
+<p><!--para 6 -->
Two identifiers have the same scope if and only if their scopes terminate at the same
point.
-<p><!--para 7-->
+<p><!--para 7 -->
Structure, union, and enumeration tags have scope that begins just after the appearance of
the tag in a type specifier that declares the tag. Each enumeration constant has scope that
begins just after the appearance of its defining enumerator in an enumerator list. Any
other identifier has scope that begins just after the completion of its declarator.
-<p><!--para 8-->
+<p><!--para 8 -->
As a special case, a type name (which is not a declaration of an identifier) is considered to
have a scope that begins just after the place within the type name where the omitted
identifier would appear were it not omitted.
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"><h4>6.2.2 Linkages of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 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.<sup><a href="#note29"><b>29)</b></a></sup> There are
three kinds of linkage: external, internal, and none.
-<p><!--para 2-->
+<p><!--para 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
function. Within one translation unit, each declaration of an identifier with internal
linkage denotes the same object or function. Each declaration of an identifier with no
linkage denotes a unique entity.
-<p><!--para 3-->
+<p><!--para 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.<sup><a href="#note30"><b>30)</b></a></sup>
-<!--page 55 indent 4-->
-<p><!--para 4-->
+<!--page 55 -->
+<p><!--para 4 -->
For an identifier declared with the storage-class specifier extern in a scope in which a
prior declaration of that identifier is visible,<sup><a href="#note31"><b>31)</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.
-<p><!--para 5-->
+<p><!--para 5 -->
If the declaration of an identifier for a function has no storage-class specifier, its linkage
is determined exactly as if it were declared with the storage-class specifier extern. If
the declaration of an identifier for an object has file scope and no storage-class specifier,
its linkage is external.
-<p><!--para 6-->
+<p><!--para 6 -->
The following identifiers have no linkage: an identifier declared to be anything other than
an object or a function; an identifier declared to be a function parameter; a block scope
identifier for an object declared without the storage-class specifier extern.
-<p><!--para 7-->
+<p><!--para 7 -->
If, within a translation unit, the same identifier appears with both internal and external
linkage, the behavior is undefined.
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>), expressions (<a href="#6.5">6.5</a>), external definitions (<a href="#6.9">6.9</a>),
</small>
<a name="6.2.3" href="#6.2.3"><h4>6.2.3 Name spaces of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
If more than one declaration of a particular identifier is visible at any point in a
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:
structure and union specifiers (<a href="#6.7.2.1">6.7.2.1</a>), structure and union members (<a href="#6.5.2.3">6.5.2.3</a>), tags
(<a href="#6.7.2.3">6.7.2.3</a>), the goto statement (<a href="#6.8.6.1">6.8.6.1</a>).
-<!--page 56 indent 4-->
+<!--page 56 -->
<h6>footnotes</h6>
<p><small><a name="note32" href="#note32">32)</a> There is only one name space for tags even though three are possible.
</small>
<a name="6.2.4" href="#6.2.4"><h4>6.2.4 Storage durations of objects</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An object has a storage duration that determines its lifetime. There are four storage
durations: static, thread, automatic, and allocated. Allocated storage is described in
<a href="#7.22.3">7.22.3</a>.
-<p><!--para 2-->
+<p><!--para 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,<sup><a href="#note33"><b>33)</b></a></sup> and retains
its last-stored value throughout its lifetime.<sup><a href="#note34"><b>34)</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 (or just past) reaches the end of its lifetime.
-<p><!--para 3-->
+<p><!--para 3 -->
An object whose identifier is declared without the storage-class specifier
_Thread_local, and either with external or internal linkage or with the storage-class
specifier static, has static storage duration. Its lifetime is the entire execution of the
program and its stored value is initialized only once, prior to program startup.
-<p><!--para 4-->
+<p><!--para 4 -->
An object whose identifier is declared with the storage-class specifier _Thread_local
has thread storage duration. Its lifetime is the entire execution of the thread for which it
is created, and its stored value is initialized when the thread is started. There is a distinct
associated with the thread evaluating the expression. The result of attempting to
indirectly access an object with thread storage duration from a thread other than the one
with which the object is associated is implementation-defined.
-<p><!--para 5-->
+<p><!--para 5 -->
An object whose identifier is declared with no linkage and without the storage-class
specifier static has automatic storage duration, as do some compound literals. The
result of attempting to indirectly access an object with automatic storage duration from a
thread other than the one with which the object is associated is implementation-defined.
-<p><!--para 6-->
+<p><!--para 6 -->
For such an object that does not have a variable length array type, its lifetime extends
from entry into the block with which it is associated until execution of that block ends in
any way. (Entering an enclosed block or calling a function suspends, but does not end,
-<!--page 57 indent 4-->
-<p><!--para 7-->
+<!--page 57 -->
+<p><!--para 7 -->
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.<sup><a href="#note35"><b>35)</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.
-<p><!--para 8-->
+<p><!--para 8 -->
A non-lvalue expression with structure or union type, where the structure or union
contains a member with array type (including, recursively, members of all contained
structures and unions) refers to an object with automatic storage duration and temporary
</small>
<a name="6.2.5" href="#6.2.5"><h4>6.2.5 Types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The meaning of a value stored in an object or returned by a function is determined by the
type of the expression used to access it. (An identifier declared to be an object is the
simplest such expression; the type is specified in the declaration of the identifier.) Types
that describe functions). At various points within a translation unit an object type may be
incomplete (lacking sufficient information to determine the size of objects of that type) or
complete (having sufficient information).<sup><a href="#note37"><b>37)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
An object declared as type _Bool is large enough to store the values 0 and 1.
-<p><!--para 3-->
+<p><!--para 3 -->
An object declared as type char is large enough to store any member of the basic
execution character set. If a member of the basic execution character set is stored in a
char object, its value is guaranteed to be nonnegative. If any other character is stored in
a char object, the resulting value is implementation-defined but shall be within the range
of values that can be represented in that type.
-<p><!--para 4-->
+<p><!--para 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.<sup><a href="#note38"><b>38)</b></a></sup> The standard and extended
signed integer types are collectively called signed integer types.<sup><a href="#note39"><b>39)</b></a></sup>
-<!--page 58 indent 5-->
-<p><!--para 5-->
+<!--page 58 -->
+<p><!--para 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
INT_MIN to INT_MAX as defined in the header <a href="#7.10"><limits.h></a>).
-<p><!--para 6-->
+<p><!--para 6 -->
For each of the signed integer types, there is a corresponding (but different) unsigned
integer type (designated with the keyword unsigned) that uses the same amount of
storage (including sign information) and has the same alignment requirements. The type
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.<sup><a href="#note40"><b>40)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 7 -->
The standard signed integer types and standard unsigned integer types are collectively
called the standard integer types, the extended signed integer types and extended
unsigned integer types are collectively called the extended integer types.
-<p><!--para 8-->
+<p><!--para 8 -->
For any two integer types with the same signedness and different integer conversion rank
(see <a href="#6.3.1.1">6.3.1.1</a>), the range of values of the type with smaller integer conversion rank is a
subrange of the values of the other type.
-<p><!--para 9-->
+<p><!--para 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.<sup><a href="#note41"><b>41)</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.
-<p><!--para 10-->
+<p><!--para 10 -->
There are three real floating types, designated as float, double, and long
double.<sup><a href="#note42"><b>42)</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.
-<!--page 59 indent 5-->
-<p><!--para 11-->
+<!--page 59 -->
+<p><!--para 11 -->
There are three complex types, designated as float _Complex, double
_Complex, and long double _Complex.<sup><a href="#note43"><b>43)</b></a></sup> (Complex types are a conditional
feature that implementations need not support; see <a href="#6.10.8.3">6.10.8.3</a>.) The real floating and
complex types are collectively called the floating types.
-<p><!--para 12-->
+<p><!--para 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
by deleting the keyword _Complex from the type name.
-<p><!--para 13-->
+<p><!--para 13 -->
Each complex type has the same representation and alignment requirements as an array
type containing exactly two elements of the corresponding real type; the first element is
equal to the real part, and the second element to the imaginary part, of the complex
number.
-<p><!--para 14-->
+<p><!--para 14 -->
The type char, the signed and unsigned integer types, and the floating types are
collectively called the basic types. The basic types are complete object types. Even if the
implementation defines two or more basic types to have the same representation, they are
nevertheless different types.<sup><a href="#note44"><b>44)</b></a></sup>
-<p><!--para 15-->
+<p><!--para 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.<sup><a href="#note45"><b>45)</b></a></sup>
-<p><!--para 16-->
+<p><!--para 16 -->
An enumeration comprises a set of named integer constant values. Each distinct
enumeration constitutes a different enumerated type.
-<p><!--para 17-->
+<p><!--para 17 -->
The type char, the signed and unsigned integer types, and the enumerated types are
collectively called integer types. The integer and real floating types are collectively called
real types.
-<p><!--para 18-->
+<p><!--para 18 -->
Integer and floating types are collectively called arithmetic types. Each arithmetic type
belongs to one type domain: the real type domain comprises the real types, the complex
type domain comprises the complex types.
-<p><!--para 19-->
+<p><!--para 19 -->
The void type comprises an empty set of values; it is an incomplete object type that
cannot be completed.
-<!--page 60 indent 5-->
-<p><!--para 20-->
+<!--page 60 -->
+<p><!--para 20 -->
Any number of derived types can be constructed from the object and function types, as
follows:
<ul>
support; see <a href="#6.10.8.3">6.10.8.3</a>.)
</ul>
These methods of constructing derived types can be applied recursively.
-<p><!--para 21-->
+<p><!--para 21 -->
Arithmetic types and pointer types are collectively called scalar types. Array and
structure types are collectively called aggregate types.<sup><a href="#note46"><b>46)</b></a></sup>
-<p><!--para 22-->
+<p><!--para 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
-<!--page 61 indent 5-->
+<!--page 61 -->
type. It is completed, for all declarations of that type, by declaring the same structure or
union tag with its defining content later in the same scope.
-<p><!--para 23-->
+<p><!--para 23 -->
A type has known constant size if the type is not incomplete and is not a variable length
array type.
-<p><!--para 24-->
+<p><!--para 24 -->
Array, function, and pointer types are collectively called derived declarator types. A
declarator type derivation from a type T is the construction of a derived declarator type
from T by the application of an array-type, a function-type, or a pointer-type derivation to
T.
-<p><!--para 25-->
+<p><!--para 25 -->
A type is characterized by its type category, which is either the outermost derivation of a
derived type (as noted above in the construction of derived types), or the type itself if the
type consists of no derived types.
-<p><!--para 26-->
+<p><!--para 26 -->
Any type so far mentioned is an unqualified type. Each unqualified type has several
qualified versions of its type,<sup><a href="#note47"><b>47)</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.<sup><a href="#note48"><b>48)</b></a></sup> A derived type is not qualified by the
qualifiers (if any) of the type from which it is derived.
-<p><!--para 27-->
+<p><!--para 27 -->
Further, there is the _Atomic qualifier. The presence of the _Atomic qualifier
designates an atomic type. The size, representation, and alignment of an atomic type
need not be the same as those of the corresponding unqualified type. Therefore, this
atomic version of a type is permitted along with the other qualified versions of a type.
The phrase ''qualified or unqualified type'', without specific mention of atomic, does not
include the atomic types.
-<p><!--para 28-->
+<p><!--para 28 -->
A pointer to void shall have the same representation and alignment requirements as a
pointer to a character type.48) Similarly, pointers to qualified or unqualified versions of
compatible types shall have the same representation and alignment requirements. All
as each other. All pointers to union types shall have the same representation and
alignment requirements as each other. Pointers to other types need not have the same
representation or alignment requirements.
-<p><!--para 29-->
+<p><!--para 29 -->
EXAMPLE 1 The type designated as ''float *'' has type ''pointer to float''. Its type category is
pointer, not a floating type. The const-qualified version of this type is designated as ''float * const''
whereas the type designated as ''const float *'' is not a qualified type -- its type is ''pointer to const-
-<!--page 62 indent 5-->
+<!--page 62 -->
qualified float'' and is a pointer to a qualified type.
-<p><!--para 30-->
+<p><!--para 30 -->
EXAMPLE 2 The type designated as ''struct tag (*[5])(float)'' has type ''array of pointer to
function returning struct tag''. The array has length five and the function has a single parameter of type
float. Its type category is array.
<a name="6.2.6" href="#6.2.6"><h4>6.2.6 Representations of types</h4></a>
<a name="6.2.6.1" href="#6.2.6.1"><h5>6.2.6.1 General</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The representations of all types are unspecified except as stated in this subclause.
-<p><!--para 2-->
+<p><!--para 2 -->
Except for bit-fields, objects are composed of contiguous sequences of one or more bytes,
the number, order, and encoding of which are either explicitly specified or
implementation-defined.
-<p><!--para 3-->
+<p><!--para 3 -->
Values stored in unsigned bit-fields and objects of type unsigned char shall be
represented using a pure binary notation.<sup><a href="#note49"><b>49)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 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
bits the bit-field comprises in the addressable storage unit holding it. Two values (other
than NaNs) with the same object representation compare equal, but values that compare
equal may have different object representations.
-<p><!--para 5-->
+<p><!--para 5 -->
Certain object representations need not represent a value of the object type. If the stored
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.<sup><a href="#note50"><b>50)</b></a></sup> Such a representation is called
a trap representation.
-<p><!--para 6-->
+<p><!--para 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.<sup><a href="#note51"><b>51)</b></a></sup> The value of a structure or union object is never a trap
-<!--page 63 indent 4-->
+<!--page 63 -->
representation, even though the value of a member of the structure or union object may be
a trap representation.
-<p><!--para 7-->
+<p><!--para 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.
-<p><!--para 8-->
+<p><!--para 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.<sup><a href="#note52"><b>52)</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.
-<p><!--para 9-->
+<p><!--para 9 -->
Loads and stores of objects with atomic types are done with
memory_order_seq_cst semantics.
<p><b> Forward references</b>: declarations (<a href="#6.7">6.7</a>), expressions (<a href="#6.5">6.5</a>), lvalues, arrays, and function
</small>
<a name="6.2.6.2" href="#6.2.6.2"><h5>6.2.6.2 Integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
For unsigned integer types other than unsigned char, the bits of the object
representation shall be divided into two groups: value bits and padding bits (there need
not be any of the latter). If there are N value bits, each bit shall represent a different
power of 2 between 1 and 2 N -1 , so that objects of that type shall be capable of
representing values from 0 to 2 N - 1 using a pure binary representation; this shall be
known as the value representation. The values of any padding bits are unspecified.<sup><a href="#note53"><b>53)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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;
signed char shall not have any padding bits. There shall be exactly one sign bit.
representation of the corresponding unsigned type (if there are M value bits in the signed
type and N in the unsigned type, then M <= N ). If the sign bit is zero, it shall not affect
-<!--page 64 indent 4-->
+<!--page 64 -->
the resulting value. If the sign bit is one, the value shall be modified in one of the
following ways:
<ul>
complement), is a trap representation or a normal value. In the case of sign and
magnitude and ones' complement, if this representation is a normal value it is called a
negative zero.
-<p><!--para 3-->
+<p><!--para 3 -->
If the implementation supports negative zeros, they shall be generated only by:
<ul>
<li> the &, |, ^, ~, <<, and >> operators with operands that produce such a value;
</ul>
It is unspecified whether these cases actually generate a negative zero or a normal zero,
and whether a negative zero becomes a normal zero when stored in an object.
-<p><!--para 4-->
+<p><!--para 4 -->
If the implementation does not support negative zeros, the behavior of the &, |, ^, ~, <<,
and >> operators with operands that would produce such a value is undefined.
-<p><!--para 5-->
+<p><!--para 5 -->
The values of any padding bits are unspecified.<sup><a href="#note54"><b>54)</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
zero in that type.
-<p><!--para 6-->
+<p><!--para 6 -->
The precision of an integer type is the number of bits it uses to represent values,
excluding any sign and padding bits. The width of an integer type is the same but
including any sign bit; thus for unsigned integer types the two values are the same, while
-<!--page 65 indent 4-->
+<!--page 65 -->
<h6>footnotes</h6>
<p><small><a name="note53" href="#note53">53)</a> Some combinations of padding bits might generate trap representations, for example, if one padding
</small>
<a name="6.2.7" href="#6.2.7"><h4>6.2.7 Compatible type and composite type</h4></a>
-<p><!--para 1-->
+<p><!--para 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="#6.7.6">6.7.6</a> for declarators.<sup><a href="#note55"><b>55)</b></a></sup> Moreover, two structure,
with the same name. For two structures, corresponding members shall be declared in the
same order. For two structures or unions, corresponding bit-fields shall have the same
widths. For two enumerations, corresponding members shall have the same values.
-<p><!--para 2-->
+<p><!--para 2 -->
All declarations that refer to the same object or function shall have compatible type;
otherwise, the behavior is undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
A composite type can be constructed from two types that are compatible; it is a type that
is compatible with both of the two types and satisfies the following conditions:
<ul>
the composite type is a function prototype with the parameter type list.
-<!--page 66 indent 4-->
+<!--page 66 -->
<li> If both types are function types with parameter type lists, the type of each parameter
in the composite parameter type list is the composite type of the corresponding
parameters.
</ul>
These rules apply recursively to the types from which the two types are derived.
-<p><!--para 4-->
+<p><!--para 4 -->
For an identifier with internal or external linkage declared in a scope in which a prior
declaration of that identifier is visible,<sup><a href="#note56"><b>56)</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.
<p><b> Forward references</b>: array declarators (<a href="#6.7.6.2">6.7.6.2</a>).
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE Given the following two file scope declarations:
<pre>
int f(int (*)(), double (*)[3]);
</small>
<a name="6.2.8" href="#6.2.8"><h4>6.2.8 Alignment of objects</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Complete object types have alignment requirements which place restrictions on the
addresses at which objects of that type may be allocated. An alignment is an
implementation-defined integer value representing the number of bytes between
successive addresses at which a given object can be allocated. An object type imposes an
alignment requirement on every object of that type: stricter alignment can be requested
using the _Alignas keyword.
-<p><!--para 2-->
+<p><!--para 2 -->
A fundamental alignment is represented by an alignment less than or equal to the greatest
alignment supported by the implementation in all contexts, which is equal to
alignof(max_align_t).
-<p><!--para 3-->
+<p><!--para 3 -->
An extended alignment is represented by an alignment greater than
alignof(max_align_t). It is implementation-defined whether any extended
alignments are supported and the contexts in which they are supported. A type having an
extended alignment requirement is an over-aligned type.<sup><a href="#note57"><b>57)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
Alignments are represented as values of the type size_t. Valid alignments include only
those values returned by an alignof expression for fundamental types, plus an
additional implementation-defined set of values, which may be empty. Every valid
alignment value shall be a nonnegative integral power of two.
-<!--page 67 indent 4-->
-<p><!--para 5-->
+<!--page 67 -->
+<p><!--para 5 -->
Alignments have an order from weaker to stronger or stricter alignments. Stricter
alignments have larger alignment values. An address that satisfies an alignment
requirement also satisfies any weaker valid alignment requirement.
-<p><!--para 6-->
+<p><!--para 6 -->
The alignment requirement of a complete type can be queried using an alignof
expression. The types char, signed char, and unsigned char shall have the
weakest alignment requirement.
-<p><!--para 7-->
+<p><!--para 7 -->
Comparing alignments is meaningful and provides the obvious results:
<ul>
<li> Two alignments are equal when their numeric values are equal.
<li> Two alignments are different when their numeric values are not equal.
<li> When an alignment is larger than another it represents a stricter alignment.
-<!--page 68 indent 4-->
+<!--page 68 -->
</ul>
<h6>footnotes</h6>
</small>
<a name="6.3" href="#6.3"><h3>6.3 Conversions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Several operators convert operand values from one type to another automatically. This
subclause specifies the result required from such an implicit conversion, as well as those
that result from a cast operation (an explicit conversion). The list in <a href="#6.3.1.8">6.3.1.8</a> summarizes
the conversions performed by most ordinary operators; it is supplemented as required by
the discussion of each operator in <a href="#6.5">6.5</a>.
-<p><!--para 2-->
+<p><!--para 2 -->
Conversion of an operand value to a compatible type causes no change to the value or the
representation.
<p><b> Forward references</b>: cast operators (<a href="#6.5.4">6.5.4</a>).
<a name="6.3.1" href="#6.3.1"><h4>6.3.1 Arithmetic operands</h4></a>
<a name="6.3.1.1" href="#6.3.1.1"><h5>6.3.1.1 Boolean, characters, and integers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Every integer type has an integer conversion rank defined as follows:
<ul>
<li> No two signed integer types shall have the same rank, even if they have the same
<li> For all integer types T1, T2, and T3, if T1 has greater rank than T2 and T2 has
greater rank than T3, then T1 has greater rank than T3.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The following may be used in an expression wherever an int or unsigned int may
be used:
-<!--page 69 indent 4-->
+<!--page 69 -->
<ul>
<li> An object or expression with an integer type (other than int or unsigned int)
whose integer conversion rank is less than or equal to the rank of int and
bit-field), the value is converted to an int; otherwise, it is converted to an unsigned
int. These are called the integer promotions.<sup><a href="#note58"><b>58)</b></a></sup> All other types are unchanged by the
integer promotions.
-<p><!--para 3-->
+<p><!--para 3 -->
The integer promotions preserve value including sign. As discussed earlier, whether a
''plain'' char is treated as signed is implementation-defined.
<p><b> Forward references</b>: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>), structure and union specifiers
</small>
<a name="6.3.1.2" href="#6.3.1.2"><h5>6.3.1.2 Boolean type</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When any scalar value is converted to _Bool, the result is 0 if the value compares equal
to 0; otherwise, the result is 1.<sup><a href="#note59"><b>59)</b></a></sup>
</small>
<a name="6.3.1.3" href="#6.3.1.3"><h5>6.3.1.3 Signed and unsigned integers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value with integer type is converted to another integer type other than _Bool, if
the value can be represented by the new type, it is unchanged.
-<p><!--para 2-->
+<p><!--para 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.<sup><a href="#note60"><b>60)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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.
</small>
<a name="6.3.1.4" href="#6.3.1.4"><h5>6.3.1.4 Real floating and integer</h5></a>
-<p><!--para 1-->
+<p><!--para 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.<sup><a href="#note61"><b>61)</b></a></sup>
-<!--page 70 indent 4-->
-<p><!--para 2-->
+<!--page 70 -->
+<p><!--para 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
</small>
<a name="6.3.1.5" href="#6.3.1.5"><h5>6.3.1.5 Real floating types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value of real floating 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
required by the new type.
<a name="6.3.1.6" href="#6.3.1.6"><h5>6.3.1.6 Complex types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value of complex type is converted to another complex type, both the real and
imaginary parts follow the conversion rules for the corresponding real types.
<a name="6.3.1.7" href="#6.3.1.7"><h5>6.3.1.7 Real and complex</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value of real type is converted to a complex type, the real part of the complex
result value is determined by the rules of conversion to the corresponding real type and
the imaginary part of the complex result value is a positive zero or an unsigned zero.
-<p><!--para 2-->
+<p><!--para 2 -->
When a value of complex type is converted to a real type, the imaginary part of the
complex value is discarded and the value of the real part is converted according to the
conversion rules for the corresponding real type.
<a name="6.3.1.8" href="#6.3.1.8"><h5>6.3.1.8 Usual arithmetic conversions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Many operators that expect operands of arithmetic type cause conversions and yield result
types in a similar way. The purpose is to determine a common real type for the operands
and result. For the specified operands, each operand is converted, without change of type
explicitly stated otherwise, the common real type is also the corresponding real type of
the result, whose type domain is the type domain of the operands if they are the same,
and complex otherwise. This pattern is called the usual arithmetic conversions:
-<!--page 71 indent 4-->
-<p><!--para 2-->
+<!--page 71 -->
+<p><!--para 2 -->
<pre>
First, if the corresponding real type of either operand is long double, the other
operand is converted, without change of type domain, to a type whose
-<!--page 72 indent 4-->
+<!--page 72 -->
<h6>footnotes</h6>
<p><small><a name="note62" href="#note62">62)</a> For example, addition of a double _Complex and a float entails just the conversion of the
<a name="6.3.2" href="#6.3.2"><h4>6.3.2 Other operands</h4></a>
<a name="6.3.2.1" href="#6.3.2.1"><h5>6.3.2.1 Lvalues, arrays, and function designators</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An lvalue is an expression (with an object type other than void) that potentially
designates an object;<sup><a href="#note64"><b>64)</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
qualified type, and if it is a structure or union, does not have any member (including,
recursively, any member or element of all contained aggregates or unions) with a const-
qualified type.
-<p><!--para 2-->
+<p><!--para 2 -->
Except when it is the operand of the sizeof operator, the unary & operator, the ++
operator, the -- operator, or the left operand of the . operator or an assignment operator,
an lvalue that does not have array type is converted to the value stored in the designated
storage class (never had its address taken), and that object is uninitialized (not declared
with an initializer and no assignment to it has been performed prior to use), the behavior
is undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
Except when it is the operand of the sizeof operator or the unary & operator, or is a
string literal used to initialize an array, an expression that has type ''array of type'' is
converted to an expression with type ''pointer to type'' that points to the initial element of
the array object and is not an lvalue. If the array object has register storage class, the
behavior is undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
A function designator is an expression that has function type. Except when it is the
operand of the sizeof operator<sup><a href="#note65"><b>65)</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
-<!--page 73 indent 4-->
+<!--page 73 -->
function returning type''.
<p><b> Forward references</b>: address and indirection operators (<a href="#6.5.3.2">6.5.3.2</a>), assignment operators
(<a href="#6.5.16">6.5.16</a>), common definitions <a href="#7.19"><stddef.h></a> (<a href="#7.19">7.19</a>), initialization (<a href="#6.7.9">6.7.9</a>), postfix
</small>
<a name="6.3.2.2" href="#6.3.2.2"><h5>6.3.2.2 void</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The (nonexistent) value of a void expression (an expression that has type void) shall not
be used in any way, and implicit or explicit conversions (except to void) shall not be
applied to such an expression. If an expression of any other type is evaluated as a void
side effects.)
<a name="6.3.2.3" href="#6.3.2.3"><h5>6.3.2.3 Pointers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A pointer to void may be converted to or from a pointer to any object type. A pointer to
any object type may be converted to a pointer to void and back again; the result shall
compare equal to the original pointer.
-<p><!--para 2-->
+<p><!--para 2 -->
For any qualifier q, a pointer to a non-q-qualified type may be converted to a pointer to
the q-qualified version of the type; the values stored in the original and converted pointers
shall compare equal.
-<p><!--para 3-->
+<p><!--para 3 -->
An integer constant expression with the value 0, or such an expression cast to type
void *, is called a null pointer constant.<sup><a href="#note66"><b>66)</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.
-<p><!--para 4-->
+<p><!--para 4 -->
Conversion of a null pointer to another pointer type yields a null pointer of that type.
Any two null pointers shall compare equal.
-<p><!--para 5-->
+<p><!--para 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.<sup><a href="#note67"><b>67)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 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
-<!--page 74 indent 4-->
-<p><!--para 7-->
+<!--page 74 -->
+<p><!--para 7 -->
A pointer to an object type may be converted to a pointer to a different object type. If the
resulting pointer is not correctly aligned<sup><a href="#note68"><b>68)</b></a></sup> for the referenced 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 converted to a pointer to a character type,
the result points to the lowest addressed byte of the object. Successive increments of the
result, up to the size of the object, yield pointers to the remaining bytes of the object.
-<p><!--para 8-->
+<p><!--para 8 -->
A pointer to a function of one type may be converted to a pointer to a function of another
type and back again; the result shall compare equal to the original pointer. If a converted
pointer is used to call a function whose type is not compatible with the referenced type,
-<!--page 75 indent 4-->
+<!--page 75 -->
<h6>footnotes</h6>
<p><small><a name="note66" href="#note66">66)</a> The macro NULL is defined in <a href="#7.19"><stddef.h></a> (and other headers) as a null pointer constant; see <a href="#7.19">7.19</a>.
<a name="6.4" href="#6.4"><h3>6.4 Lexical elements</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
token:
keyword
punctuator
each non-white-space character that cannot be one of the above</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each preprocessing token that is converted to a token shall have the lexical form of a
keyword, an identifier, a constant, a string literal, or a punctuator.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A token is the minimal lexical element of the language in translation phases 7 and 8. The
categories of tokens are: keywords, identifiers, constants, string literals, and punctuators.
A preprocessing token is the minimal lexical element of the language in translation
-<!--page 76 indent 4-->
-<p><!--para 4-->
+<!--page 76 -->
+<p><!--para 4 -->
If the input stream has been parsed into preprocessing tokens up to a given character, the
next preprocessing token is the longest sequence of characters that could constitute a
preprocessing token. There is one exception to this rule: header name preprocessing
implementation-defined locations within #pragma directives. In such contexts, a
sequence of characters that could be either a header name or a string literal is recognized
as the former.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 1 The program fragment 1Ex is parsed as a preprocessing number token (one that is not a
valid floating or integer constant token), even though a parse as the pair of preprocessing tokens 1 and Ex
might produce a valid expression (for example, if Ex were a macro defined as +1). Similarly, the program
fragment 1E1 is parsed as a preprocessing number (one that is a valid floating constant token), whether or
not E is a macro name.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 2 The program fragment x+++++y is parsed as x ++ ++ + y, which violates a constraint on
increment operators, even though the parse x ++ + ++ y might yield a correct expression.
<a name="6.4.1" href="#6.4.1"><h4>6.4.1 Keywords</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
keyword: one of
alignof goto union
float switch _Thread_local
for typedef</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The above tokens (case sensitive) are reserved (in translation phases 7 and 8) for use as
keywords, and shall not be used otherwise. The keyword _Imaginary is reserved for
-<!--page 77 indent 4-->
+<!--page 77 -->
specifying imaginary types.<sup><a href="#note70"><b>70)</b></a></sup>
<h6>footnotes</h6>
<a name="6.4.2.1" href="#6.4.2.1"><h5>6.4.2.1 General</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
identifier:
identifier-nondigit
digit: one of
0 1 2 3 4 5 6 7 8 9</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier is a sequence of nondigit characters (including the underscore _, the
lowercase and uppercase Latin letters, and other characters) and digits, which designates
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.
-<p><!--para 3-->
+<p><!--para 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 D.1.<sup><a href="#note71"><b>71)</b></a></sup> The initial character
shall not be a universal character name designating a character whose encoding falls into
-<!--page 78 indent 4-->
-<p><!--para 4-->
+<!--page 78 -->
+<p><!--para 4 -->
When preprocessing tokens are converted to tokens during translation phase 7, if a
preprocessing token could be converted to either a keyword or an identifier, it is converted
to a keyword.
Implementation limits
-<p><!--para 5-->
+<p><!--para 5 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, an implementation may limit the number of significant initial
characters in an identifier; the limit for an external name (an identifier that has external
linkage) may be more restrictive than that for an internal name (a macro name or an
identifier that does not have external linkage). The number of significant characters in an
identifier is implementation-defined.
-<p><!--para 6-->
+<p><!--para 6 -->
Any identifiers that differ in a significant character are different identifiers. If two
identifiers differ only in nonsignificant characters, the behavior is undefined.
<p><b> Forward references</b>: universal character names (<a href="#6.4.3">6.4.3</a>), macro replacement (<a href="#6.10.3">6.10.3</a>).
<a name="6.4.2.2" href="#6.4.2.2"><h5>6.4.2.2 Predefined identifiers</h5></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The identifier __func__ shall be implicitly declared by the translator as if,
immediately following the opening brace of each function definition, the declaration
<pre>
static const char __func__[] = "function-name";</pre>
appeared, where function-name is the name of the lexically-enclosing function.<sup><a href="#note72"><b>72)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE Consider the code fragment:
<pre>
#include <a href="#7.21"><stdio.h></a>
-<!--page 79 indent 4-->
+<!--page 79 -->
<h6>footnotes</h6>
<p><small><a name="note72" href="#note72">72)</a> Since the name __func__ is reserved for any use by the implementation (<a href="#7.1.3">7.1.3</a>), if any other
<a name="6.4.3" href="#6.4.3"><h4>6.4.3 Universal character names</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
universal-character-name:
\u hex-quad
hexadecimal-digit hexadecimal-digit
hexadecimal-digit hexadecimal-digit</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A universal character name shall not specify a character whose short identifier is less than
00A0 other than 0024 ($), 0040 (@), or 0060 ('), nor one in the range D800 through
DFFF inclusive.<sup><a href="#note73"><b>73)</b></a></sup>
<h6>Description</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Universal character names may be used in identifiers, character constants, and string
literals to designate characters that are not in the basic character set.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The universal character name \Unnnnnnnn designates the character whose eight-digit
short identifier (as specified by ISO/IEC 10646) is nnnnnnnn.<sup><a href="#note74"><b>74)</b></a></sup> Similarly, the universal
character name \unnnn designates the character whose four-digit short identifier is nnnn
-<!--page 80 indent 4-->
+<!--page 80 -->
<h6>footnotes</h6>
<p><small><a name="note73" href="#note73">73)</a> The disallowed characters are the characters in the basic character set and the code positions reserved
<a name="6.4.4" href="#6.4.4"><h4>6.4.4 Constants</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
constant:
integer-constant
enumeration-constant
character-constant</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each constant shall have a type and the value of a constant shall be in the range of
representable values for its type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Each constant has a type, determined by its form and value, as detailed later.
<a name="6.4.4.1" href="#6.4.4.1"><h5>6.4.4.1 Integer constants</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 81 indent 4-->
+<p><!--para 1 -->
+<!--page 81 -->
<pre>
integer-constant:
decimal-constant integer-suffixopt
long-long-suffix: one of
ll LL</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An integer constant begins with a digit, but has no period or exponent part. It may have a
prefix that specifies its base and a suffix that specifies its type.
-<p><!--para 3-->
+<p><!--para 3 -->
A decimal constant begins with a nonzero digit and consists of a sequence of decimal
digits. An octal constant consists of the prefix 0 optionally followed by a sequence of the
digits 0 through 7 only. A hexadecimal constant consists of the prefix 0x or 0X followed
by a sequence of the decimal digits and the letters a (or A) through f (or F) with values
10 through 15 respectively.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The value of a decimal constant is computed base 10; that of an octal constant, base 8;
that of a hexadecimal constant, base 16. The lexically first digit is the most significant.
-<p><!--para 5-->
+<p><!--para 5 -->
The type of an integer constant is the first of the corresponding list in which its value can
be represented.
-<!--page 82 indent 4-->
+<!--page 82 -->
<pre>
Octal or Hexadecimal</pre>
Suffix Decimal Constant Constant
Both u or U unsigned long long int unsigned long long int
and ll or LL
-<p><!--para 6-->
+<p><!--para 6 -->
If an integer constant cannot be represented by any type in its list, it may have an
extended integer type, if the extended integer type can represent its value. If all of the
types in the list for the constant are signed, the extended integer type shall be signed. If
unsigned. If the list contains both signed and unsigned types, the extended integer type
may be signed or unsigned. If an integer constant cannot be represented by any type in
its list and has no extended integer type, then the integer constant has no type.
-<!--page 83 indent 4-->
+<!--page 83 -->
<a name="6.4.4.2" href="#6.4.4.2"><h5>6.4.4.2 Floating constants</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 84 indent 4-->
+<p><!--para 1 -->
+<!--page 84 -->
<pre>
floating-constant:
decimal-floating-constant
floating-suffix: one of
f l F L</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A floating constant has a significand part that may be followed by an exponent part and a
suffix that specifies its type. The components of the significand part may include a digit
sequence representing the whole-number part, followed by a period (.), followed by a
Either the whole-number part or the fraction part has to be present; for decimal floating
constants, either the period or the exponent part has to be present.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The significand part is interpreted as a (decimal or hexadecimal) rational number; the
digit sequence in the exponent part is interpreted as a decimal integer. For decimal
floating constants, the exponent indicates the power of 10 by which the significand part is
adjacent to the nearest representable value, chosen in an implementation-defined manner.
For hexadecimal floating constants when FLT_RADIX is a power of 2, the result is
correctly rounded.
-<p><!--para 4-->
+<p><!--para 4 -->
An unsuffixed floating constant has type double. If suffixed by the letter f or F, it has
type float. If suffixed by the letter l or L, it has type long double.
-<p><!--para 5-->
+<p><!--para 5 -->
Floating constants are converted to internal format as if at translation-time. The
conversion of a floating constant shall not raise an exceptional condition or a floating-
point exception at execution time. All floating constants of the same source form<sup><a href="#note75"><b>75)</b></a></sup> shall
convert to the same internal format with the same value.
Recommended practice
-<p><!--para 6-->
+<p><!--para 6 -->
The implementation should produce a diagnostic message if a hexadecimal constant
cannot be represented exactly in its evaluation format; the implementation should then
proceed with the translation of the program.
-<p><!--para 7-->
+<p><!--para 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.<sup><a href="#note76"><b>76)</b></a></sup>
-<!--page 85 indent 4-->
+<!--page 85 -->
<h6>footnotes</h6>
<p><small><a name="note75" href="#note75">75)</a> <a href="#1.23">1.23</a>, 1.230, 123e-2, 123e-02, and 1.23L are all different source forms and thus need not
<a name="6.4.4.3" href="#6.4.4.3"><h5>6.4.4.3 Enumeration constants</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
enumeration-constant:
identifier</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier declared as an enumeration constant has type int.
<p><b> Forward references</b>: enumeration specifiers (<a href="#6.7.2.2">6.7.2.2</a>).
<a name="6.4.4.4" href="#6.4.4.4"><h5>6.4.4.4 Character constants</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 86 indent 4-->
+<p><!--para 1 -->
+<!--page 86 -->
<pre>
character-constant:
' c-char-sequence '
\x hexadecimal-digit
hexadecimal-escape-sequence hexadecimal-digit</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An integer character constant is a sequence of one or more multibyte characters enclosed
in single-quotes, as in 'x'. A wide character constant is the same, except prefixed by the
letter L, u, or U. With a few exceptions detailed later, the elements of the sequence are
any members of the source character set; they are mapped in an implementation-defined
manner to members of the execution character set.
-<p><!--para 3-->
+<p><!--para 3 -->
The single-quote ', the double-quote ", the question-mark ?, the backslash \, and
arbitrary integer values are representable according to the following table of escape
sequences:
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
single quote ' \'
double quote " \"
The double-quote " and question-mark ? are representable either by themselves or by the
escape sequences \" and \?, respectively, but the single-quote ' and the backslash \
shall be represented, respectively, by the escape sequences \' and \\.
-<p><!--para 5-->
+<p><!--para 5 -->
The octal digits that follow the backslash in an octal escape sequence are taken to be part
of the construction of a single character for an integer character constant or of a single
wide character for a wide character constant. The numerical value of the octal integer so
formed specifies the value of the desired character or wide character.
-<p><!--para 6-->
+<p><!--para 6 -->
The hexadecimal digits that follow the backslash and the letter x in a hexadecimal escape
sequence are taken to be part of the construction of a single character for an integer
character constant or of a single wide character for a wide character constant. The
numerical value of the hexadecimal integer so formed specifies the value of the desired
character or wide character.
-<p><!--para 7-->
+<p><!--para 7 -->
Each octal or hexadecimal escape sequence is the longest sequence of characters that can
constitute the escape sequence.
-<p><!--para 8-->
+<p><!--para 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.<sup><a href="#note77"><b>77)</b></a></sup>
-<!--page 87 indent 5-->
+<!--page 87 -->
<h6>Constraints</h6>
-<p><!--para 9-->
+<p><!--para 9 -->
The value of an octal or hexadecimal escape sequence shall be in the range of
representable values for the corresponding type:
<pre>
u char16_t
U char32_t</pre>
<h6>Semantics</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
An integer character constant has type int. The value of an integer character constant
containing a single character that maps to a single-byte execution character is the
numerical value of the representation of the mapped character interpreted as an integer.
a single character or escape sequence, its value is the one that results when an object with
type char whose value is that of the single character or escape sequence is converted to
type int.
-<p><!--para 11-->
+<p><!--para 11 -->
A wide character constant prefixed by the letter L has type wchar_t, an integer type
defined in the <a href="#7.19"><stddef.h></a> header; a wide character constant prefixed by the letter u or
U has type char16_t or char32_t, respectively, unsigned integer types defined in the
members of the extended execution character set, or containing a multibyte character or
escape sequence not represented in the extended execution character set, is
implementation-defined.
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE 1 The construction '\0' is commonly used to represent the null character.
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 2 Consider implementations that use two's complement representation for integers and eight
bits for objects that have type char. In an implementation in which type char has the same range of
values as signed char, the integer character constant '\xFF' has the value -1; if type char has the
-<!--page 88 indent 5-->
-<p><!--para 14-->
+<!--page 88 -->
+<p><!--para 14 -->
EXAMPLE 3 Even if eight bits are used for objects that have type char, the construction '\x123'
specifies an integer character constant containing only one character, since a hexadecimal escape sequence
is terminated only by a non-hexadecimal character. To specify an integer character constant containing the
escape sequence is terminated after three octal digits. (The value of this two-character integer character
constant is implementation-defined.)
-<p><!--para 15-->
+<p><!--para 15 -->
EXAMPLE 4 Even if 12 or more bits are used for objects that have type wchar_t, the construction
L'\1234' specifies the implementation-defined value that results from the combination of the values
0123 and '4'.
<a name="6.4.5" href="#6.4.5"><h4>6.4.5 String literals</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
string-literal:
encoding-prefixopt " s-char-sequenceopt "
the double-quote ", backslash \, or new-line character
escape-sequence</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A sequence of adjacent string literal tokens shall not include both a wide string literal and
a UTF-8 string literal.
<h6>Description</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A character string literal is a sequence of zero or more multibyte characters enclosed in
double-quotes, as in "xyz". A UTF-8 string literal is the same, except prefixed by u8.
A wide string literal is the same, except prefixed by the letter L, u, or U.
-<p><!--para 4-->
+<p><!--para 4 -->
The same considerations apply to each element of the sequence in a string literal as if it
were in an integer character constant (for a character or UTF-8 string literal) or a wide
character constant (for a wide string literal), except that the single-quote ' is
representable either by itself or by the escape sequence \', but the double-quote " shall
-<!--page 89 indent 4-->
+<!--page 89 -->
be represented by the escape sequence \".
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
In translation phase 6, the multibyte character sequences specified by any sequence of
adjacent character and identically-prefixed string literal tokens are concatenated into a
single multibyte character sequence. If any of the tokens has an encoding prefix, the
is treated as a character string literal. Whether differently-prefixed wide string literal
tokens can be concatenated and, if so, the treatment of the resulting multibyte character
sequence are implementation-defined.
-<p><!--para 6-->
+<p><!--para 6 -->
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.<sup><a href="#note78"><b>78)</b></a></sup> The multibyte character
sequence is then used to initialize an array of static storage duration and length just
its type, with an implementation-defined current locale. The value of a string literal
containing a multibyte character or escape sequence not represented in the execution
character set is implementation-defined.
-<p><!--para 7-->
+<p><!--para 7 -->
It is unspecified whether these arrays are distinct provided their elements have the
appropriate values. If the program attempts to modify such an array, the behavior is
undefined.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 1 This pair of adjacent character string literals
<pre>
"\x12" "3"</pre>
because escape sequences are converted into single members of the execution character set just prior to
adjacent string literal concatenation.
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 2 Each of the sequences of adjacent string literal tokens
-<!--page 90 indent 4-->
+<!--page 90 -->
<pre>
"a" "b" L"c"
"a" L"b" "c"
<a name="6.4.6" href="#6.4.6"><h4>6.4.6 Punctuators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
punctuator: one of
[ ] ( ) { } . ->
, # ##
<: :> <% %> %: %:%:</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A punctuator is a symbol that has independent syntactic and semantic significance.
Depending on context, it may specify an operation to be performed (which in turn may
yield a value or a function designator, produce a side effect, or some combination thereof)
in which case it is known as an operator (other forms of operator also exist in some
contexts). An operand is an entity on which an operator acts.
-<!--page 91 indent 4-->
-<p><!--para 3-->
+<!--page 91 -->
+<p><!--para 3 -->
In all aspects of the language, the six tokens<sup><a href="#note79"><b>79)</b></a></sup>
<pre>
<: :> <% %> %: %:%:</pre>
<a name="6.4.7" href="#6.4.7"><h4>6.4.7 Header names</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
header-name:
< h-char-sequence >
any member of the source character set except
the new-line character and "</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sequences in both forms of header names are mapped in an implementation-defined
manner to headers or external source file names as specified in <a href="#6.10.2">6.10.2</a>.
-<p><!--para 3-->
+<p><!--para 3 -->
If the characters ', \, ", //, or /* occur in the sequence between the < and > delimiters,
the behavior is undefined. Similarly, if the characters ', \, //, or /* occur in the
-<!--page 92 indent 4-->
+<!--page 92 -->
sequence between the " delimiters, the behavior is undefined.<sup><a href="#note81"><b>81)</b></a></sup> Header name
preprocessing tokens are recognized only within #include preprocessing directives and
in implementation-defined locations within #pragma directives.<sup><a href="#note82"><b>82)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The following sequence of characters:
<pre>
0x3<1/a.h>1e2
<a name="6.4.8" href="#6.4.8"><h4>6.4.8 Preprocessing numbers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
pp-number:
digit
pp-number P sign
pp-number .</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A preprocessing number begins with a digit optionally preceded by a period (.) and may
be followed by valid identifier characters and the character sequences e+, e-, E+, E-,
p+, p-, P+, or P-.
-<p><!--para 3-->
+<p><!--para 3 -->
Preprocessing number tokens lexically include all floating and integer constant tokens.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
A preprocessing number does not have type or a value; it acquires both after a successful
conversion (as part of translation phase 7) to a floating constant token or an integer
constant token.
-<!--page 93 indent 4-->
+<!--page 93 -->
<a name="6.4.9" href="#6.4.9"><h4>6.4.9 Comments</h4></a>
-<p><!--para 1-->
+<p><!--para 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.<sup><a href="#note83"><b>83)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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
multibyte characters and to find the terminating new-line character.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE
<pre>
"a//b" // four-character string literal
-<!--page 94 indent 4-->
+<!--page 94 -->
<h6>footnotes</h6>
<p><small><a name="note83" href="#note83">83)</a> Thus, /* ... */ comments do not nest.
</small>
<a name="6.5" href="#6.5"><h3>6.5 Expressions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An expression is a sequence of operators and operands that specifies computation of a
value, or that designates an object or a function, or that generates side effects, or that
performs a combination thereof. The value computations of the operands of an operator
are sequenced before the value computation of the result of the operator.
-<p><!--para 2-->
+<p><!--para 2 -->
If a side effect on a scalar object is unsequenced relative to either a different side effect
on the same scalar object or a value computation using the value of the same scalar
object, the behavior is undefined. If there are multiple allowable orderings of the
subexpressions of an expression, the behavior is undefined if such an unsequenced side
effect occurs in any of the orderings.<sup><a href="#note84"><b>84)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The grouping of operators and operands is indicated by the syntax.<sup><a href="#note85"><b>85)</b></a></sup> Except as specified
later, side effects and value computations of subexpressions are unsequenced.<sup><a href="#note86"><b>86)</b></a></sup> *
-<p><!--para 4-->
+<p><!--para 4 -->
Some operators (the unary operator ~, and the binary operators <<, >>, &, ^, and |,
collectively described as bitwise operators) are required to have operands that have
integer type. These operators yield values that depend on the internal representations of
integers, and have implementation-defined and undefined aspects for signed types.
-<p><!--para 5-->
+<p><!--para 5 -->
If an exceptional condition occurs during the evaluation of an expression (that is, if the
result is not mathematically defined or not in the range of representable values for its
type), the behavior is undefined.
-<!--page 95 indent 4-->
-<p><!--para 6-->
+<!--page 95 -->
+<p><!--para 6 -->
The effective type of an object for an access to its stored value is the declared type of the
object, if any.<sup><a href="#note87"><b>87)</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
value is the effective type of the object from which the value is copied, if it has one. For
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.
-<p><!--para 7-->
+<p><!--para 7 -->
An object shall have its stored value accessed only by an lvalue expression that has one of
the following types:<sup><a href="#note88"><b>88)</b></a></sup>
<ul>
members (including, recursively, a member of a subaggregate or contained union), or
<li> a character type.
</ul>
-<p><!--para 8-->
+<p><!--para 8 -->
A floating expression may be contracted, that is, evaluated as though it were a single
operation, thereby omitting rounding errors implied by the source code and the
expression evaluation method.<sup><a href="#note89"><b>89)</b></a></sup> The FP_CONTRACT pragma in <a href="#7.12"><math.h></a> provides a
<p><b> Forward references</b>: the FP_CONTRACT pragma (<a href="#7.12.2">7.12.2</a>), copying functions (<a href="#7.23.2">7.23.2</a>).
-<!--page 96 indent 4-->
+<!--page 96 -->
<h6>footnotes</h6>
<p><small><a name="note84" href="#note84">84)</a> This paragraph renders undefined statement expressions such as
<a name="6.5.1" href="#6.5.1"><h4>6.5.1 Primary expressions</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
primary-expression:
identifier
( expression )
generic-selection</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier is a primary expression, provided it has been declared as designating an
object (in which case it is an lvalue) or a function (in which case it is a function
designator).<sup><a href="#note91"><b>91)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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>.
-<p><!--para 4-->
+<p><!--para 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>.
-<p><!--para 5-->
+<p><!--para 5 -->
A parenthesized expression is a primary expression. Its type and value are identical to
those of the unparenthesized expression. It is an lvalue, a function designator, or a void
expression if the unparenthesized expression is, respectively, an lvalue, a function
<a name="6.5.1.1" href="#6.5.1.1"><h5>6.5.1.1 Generic selection</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
generic-selection:
_Generic ( assignment-expression , generic-assoc-list )
type-name : assignment-expression
default : assignment-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A generic selection shall have no more than one default generic association. The type
name in a generic association shall specify a complete object type other than a variably
-<!--page 97 indent 4-->
+<!--page 97 -->
modified type. No two generic associations in the same generic selection shall specify
compatible types. The controlling expression of a generic selection shall have type
compatible with at most one of the types named in its generic association list. If a
generic selection has no default generic association, its controlling expression shall
have type compatible with exactly one of the types named in its generic association list.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The controlling expression of a generic selection is not evaluated. If a generic selection
has a generic association with a type name that is compatible with the type of the
controlling expression, then the result expression of the generic selection is the
expression in that generic association. Otherwise, the result expression of the generic
selection is the expression in the default generic association. None of the expressions
from any other generic association of the generic selection is evaluated.
-<p><!--para 4-->
+<p><!--para 4 -->
The type and value of a generic selection are identical to those of its result expression. It
is an lvalue, a function designator, or a void expression if its result expression is,
respectively, an lvalue, a function designator, or a void expression.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE The cbrt type-generic macro could be implemented as follows:
<pre>
#define cbrt(X) _Generic((X), \
<a name="6.5.2" href="#6.5.2"><h4>6.5.2 Postfix operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 98 indent 4-->
+<p><!--para 1 -->
+<!--page 98 -->
<pre>
postfix-expression:
primary-expression
<a name="6.5.2.1" href="#6.5.2.1"><h5>6.5.2.1 Array subscripting</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
One of the expressions shall have type ''pointer to complete object type'', the other
expression shall have integer type, and the result has type ''type''.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A postfix expression followed by an expression in square brackets [] is a subscripted
designation of an element of an array object. The definition of the subscript operator []
is that E1[E2] is identical to (*((E1)+(E2))). Because of the conversion rules that
apply to the binary + operator, if E1 is an array object (equivalently, a pointer to the
initial element of an array object) and E2 is an integer, E1[E2] designates the E2-th
element of E1 (counting from zero).
-<p><!--para 3-->
+<p><!--para 3 -->
Successive subscript operators designate an element of a multidimensional array object.
If E is an n-dimensional array (n >= 2) with dimensions i x j x . . . x k, then E (used as
other than an lvalue) is converted to a pointer to an (n - 1)-dimensional array with
implicitly as a result of subscripting, the result is the referenced (n - 1)-dimensional
array, which itself is converted into a pointer if used as other than an lvalue. It follows
from this that arrays are stored in row-major order (last subscript varies fastest).
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE Consider the array object defined by the declaration
<pre>
int x[3][5];</pre>
<a name="6.5.2.2" href="#6.5.2.2"><h5>6.5.2.2 Function calls</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The expression that denotes the called function<sup><a href="#note92"><b>92)</b></a></sup> shall have type pointer to function
returning void or returning a complete object type other than an array type.
-<p><!--para 2-->
+<p><!--para 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
-<!--page 99 indent 4-->
+<!--page 99 -->
have a type such that its value may be assigned to an object with the unqualified version
of the type of its corresponding parameter.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A postfix expression followed by parentheses () containing a possibly empty, comma-
separated list of expressions is a function call. The postfix expression denotes the called
function. The list of expressions specifies the arguments to the function.
-<p><!--para 4-->
+<p><!--para 4 -->
An argument may be an expression of any complete 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.<sup><a href="#note93"><b>93)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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. *
-<p><!--para 6-->
+<p><!--para 6 -->
If the expression that denotes the called function has a type that does not include a
prototype, the integer promotions are performed on each argument, and arguments that
have type float are promoted to double. These are called the default argument
<li> both types are pointers to qualified or unqualified versions of a character type or
void.
</ul>
-<p><!--para 7-->
+<p><!--para 7 -->
If the expression that denotes the called function has a type that does include a prototype,
the arguments are implicitly converted, as if by assignment, to the types of the
corresponding parameters, taking the type of each parameter to be the unqualified version
-<!--page 100 indent 5-->
-<p><!--para 8-->
+<!--page 100 -->
+<p><!--para 8 -->
No other conversions are performed implicitly; in particular, the number and types of
arguments are not compared with those of the parameters in a function definition that
does not include a function prototype declarator.
-<p><!--para 9-->
+<p><!--para 9 -->
If the function is defined with a type that is not compatible with the type (of the
expression) pointed to by the expression that denotes the called function, the behavior is
undefined.
-<p><!--para 10-->
+<p><!--para 10 -->
There is a sequence point after the evaluations of the function designator and the actual
arguments but before the actual call. Every evaluation in the calling function (including
other function calls) that is not otherwise specifically sequenced before or after the
execution of the body of the called function is indeterminately sequenced with respect to
the execution of the called function.<sup><a href="#note94"><b>94)</b></a></sup>
-<p><!--para 11-->
+<p><!--para 11 -->
Recursive function calls shall be permitted, both directly and indirectly through any chain
of other functions.
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE In the function call
<pre>
(*pf[f1()]) (f2(), f3() + f4())</pre>
<a name="6.5.2.3" href="#6.5.2.3"><h5>6.5.2.3 Structure and union members</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The first operand of the . operator shall have an atomic, qualified, or unqualified
structure or union type, and the second operand shall name a member of that type.
-<p><!--para 2-->
+<p><!--para 2 -->
The first operand of the -> operator shall have type ''pointer to atomic, qualified, or
unqualified structure'' or ''pointer to atomic, qualified, or unqualified union'', and the
second operand shall name a member of the type pointed to.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A postfix expression followed by the . operator and an identifier designates a member of
a structure or union object. The value is that of the named member,<sup><a href="#note95"><b>95)</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.
-<!--page 101 indent 4-->
-<p><!--para 4-->
+<!--page 101 -->
+<p><!--para 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.<sup><a href="#note96"><b>96)</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.
-<p><!--para 5-->
+<p><!--para 5 -->
Accessing a member of an atomic structure or union object results in undefined
behavior.<sup><a href="#note97"><b>97)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 6 -->
One special guarantee is made in order to simplify the use of unions: if a union contains
several structures that share a common initial sequence (see below), and if the union
object currently contains one of these structures, it is permitted to inspect the common
is visible. Two structures share a common initial sequence if corresponding members
have compatible types (and, for bit-fields, the same widths) for a sequence of one or more
initial members.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1 If f is a function returning a structure or union, and x is a member of that structure or
union, f().x is a valid postfix expression but is not an lvalue.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 2 In:
<pre>
struct s { int i; const int ci; };
-<!--page 102 indent 4-->
-<p><!--para 9-->
+<!--page 102 -->
+<p><!--para 9 -->
EXAMPLE 3 The following is a valid fragment:
<pre>
union {
<p><b> Forward references</b>: address and indirection operators (<a href="#6.5.3.2">6.5.3.2</a>), structure and union
specifiers (<a href="#6.7.2.1">6.7.2.1</a>).
-<!--page 103 indent 4-->
+<!--page 103 -->
<h6>footnotes</h6>
<p><small><a name="note95" href="#note95">95)</a> If the member used to read the contents of a union object is not the same as the member last used to
<a name="6.5.2.4" href="#6.5.2.4"><h5>6.5.2.4 Postfix increment and decrement operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The operand of the postfix increment or decrement operator shall have atomic, qualified,
or unqualified real or pointer type, and shall be a modifiable lvalue.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The result of the postfix ++ operator is the value of the operand. As a side effect, the
value of the operand object is incremented (that is, the value 1 of the appropriate type is
added to it). See the discussions of additive operators and compound assignment for
function call, the operation of postfix ++ is a single evaluation. Postfix ++ on an object
with atomic type is a read-modify-write operation with memory_order_seq_cst
memory order semantics.<sup><a href="#note98"><b>98)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The postfix -- operator is analogous to the postfix ++ operator, except that the value of
the operand is decremented (that is, the value 1 of the appropriate type is subtracted from
it).
<a name="6.5.2.5" href="#6.5.2.5"><h5>6.5.2.5 Compound literals</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The type name shall specify a complete object type or an array of unknown size, but not a
variable length array type.
-<p><!--para 2-->
+<p><!--para 2 -->
All the constraints for initializer lists in <a href="#6.7.9">6.7.9</a> also apply to compound literals.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
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.<sup><a href="#note99"><b>99)</b></a></sup>
-<!--page 104 indent 5-->
-<p><!--para 4-->
+<!--page 104 -->
+<p><!--para 4 -->
If the type name specifies an array of unknown size, the size is determined by the
initializer list as specified in <a href="#6.7.9">6.7.9</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
of the compound literal is that specified by the type name. In either case, the result is an
lvalue.
-<p><!--para 5-->
+<p><!--para 5 -->
The value of the compound literal is that of an unnamed object initialized by the
initializer list. If the compound literal occurs outside the body of a function, the object
has static storage duration; otherwise, it has automatic storage duration associated with
the enclosing block.
-<p><!--para 6-->
+<p><!--para 6 -->
All the semantic rules for initializer lists in <a href="#6.7.9">6.7.9</a> also apply to compound literals.<sup><a href="#note100"><b>100)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 7 -->
String literals, and compound literals with const-qualified types, need not designate
distinct objects.<sup><a href="#note101"><b>101)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 1 The file scope definition
<pre>
int *p = (int []){2, 4};</pre>
second, four. The expressions in this compound literal are required to be constant. The unnamed object
has static storage duration.
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 2 In contrast, in
<pre>
void f(void)
pointed to by p and the second, zero. The expressions in this compound literal need not be constant. The
unnamed object has automatic storage duration.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 3 Initializers with designations can be combined with compound literals. Structure objects
created using compound literals can be passed to functions without depending on member order:
<pre>
-<!--page 105 indent 5-->
+<!--page 105 -->
<pre>
drawline(&(struct point){.x=1, .y=1},
&(struct point){.x=3, .y=4});</pre>
-<p><!--para 11-->
+<p><!--para 11 -->
EXAMPLE 4 A read-only compound literal can be specified through constructions like:
<pre>
(const float []){1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6}</pre>
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE 5 The following three expressions have different meanings:
<pre>
"/tmp/fileXXXXXX"
two have automatic storage duration when they occur within the body of a function, and the first of these
two is modifiable.
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 6 Like string literals, const-qualified compound literals can be placed into read-only memory
and can even be shared. For example,
<pre>
(const char []){"abc"} == "abc"</pre>
might yield 1 if the literals' storage is shared.
-<p><!--para 14-->
+<p><!--para 14 -->
EXAMPLE 7 Since compound literals are unnamed, a single compound literal cannot specify a circularly
linked object. For example, there is no way to write a self-referential compound literal that could be used
as the function argument in place of the named object endless_zeros below:
struct int_list endless_zeros = {0, &endless_zeros};
eval(endless_zeros);</pre>
-<p><!--para 15-->
+<p><!--para 15 -->
EXAMPLE 8 Each compound literal creates only a single object in a given scope:
<pre>
struct s { int i; };
return p == q && q->i == 1;
}</pre>
The function f() always returns the value 1.
-<p><!--para 16-->
+<p><!--para 16 -->
Note that if an iteration statement were used instead of an explicit goto and a labeled statement, the
lifetime of the unnamed object would be the body of the loop only, and on entry next time around p would
have an indeterminate value, which would result in undefined behavior.
<p><b> Forward references</b>: type names (<a href="#6.7.7">6.7.7</a>), initialization (<a href="#6.7.9">6.7.9</a>).
-<!--page 106 indent 4-->
+<!--page 106 -->
<h6>footnotes</h6>
<p><small><a name="note99" href="#note99">99)</a> Note that this differs from a cast expression. For example, a cast specifies a conversion to scalar types
<a name="6.5.3" href="#6.5.3"><h4>6.5.3 Unary operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
unary-expression:
postfix-expression
<a name="6.5.3.1" href="#6.5.3.1"><h5>6.5.3.1 Prefix increment and decrement operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The operand of the prefix increment or decrement operator shall have atomic, qualified,
or unqualified real or pointer type, and shall be a modifiable lvalue.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The value of the operand of the prefix ++ operator is incremented. The result is the new
value of the operand after incrementation. The expression ++E is equivalent to (E+=1).
See the discussions of additive operators and compound assignment for information on
constraints, types, side effects, and conversions and the effects of operations on pointers.
-<p><!--para 3-->
+<p><!--para 3 -->
The prefix -- operator is analogous to the prefix ++ operator, except that the value of the
operand is decremented.
<p><b> Forward references</b>: additive operators (<a href="#6.5.6">6.5.6</a>), compound assignment (<a href="#6.5.16.2">6.5.16.2</a>).
<a name="6.5.3.2" href="#6.5.3.2"><h5>6.5.3.2 Address and indirection operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The operand of the unary & operator shall be either a function designator, the result of a
[] or unary * operator, or an lvalue that designates an object that is not a bit-field and is
not declared with the register storage-class specifier.
-<p><!--para 2-->
+<p><!--para 2 -->
The operand of the unary * operator shall have pointer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The unary & operator yields the address of its operand. If the operand has type ''type'',
the result has type ''pointer to type''. If the operand is the result of a unary * operator,
neither that operator nor the & operator is evaluated and the result is as if both were
omitted, except that the constraints on the operators still apply and the result is not an
-<!--page 107 indent 4-->
+<!--page 107 -->
lvalue. Similarly, if the operand is the result of a [] operator, neither the & operator nor
the unary * that is implied by the [] is evaluated and the result is as if the & operator
were removed and the [] operator were changed to a + operator. Otherwise, the result is
a pointer to the object or function designated by its operand.
-<p><!--para 4-->
+<p><!--para 4 -->
The unary * operator denotes indirection. If the operand points to a function, the result is
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
<a name="6.5.3.3" href="#6.5.3.3"><h5>6.5.3.3 Unary arithmetic operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The operand of the unary + or - operator shall have arithmetic type; of the ~ operator,
integer type; of the ! operator, scalar type.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The result of the unary + operator is the value of its (promoted) operand. The integer
promotions are performed on the operand, and the result has the promoted type.
-<p><!--para 3-->
+<p><!--para 3 -->
The result of the unary - operator is the negative of its (promoted) operand. The integer
promotions are performed on the operand, and the result has the promoted type.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the ~ operator is the bitwise complement of its (promoted) operand (that is,
each bit in the result is set if and only if the corresponding bit in the converted operand is
not set). The integer promotions are performed on the operand, and the result has the
promoted type. If the promoted type is an unsigned type, the expression ~E is equivalent
to the maximum value representable in that type minus E.
-<p><!--para 5-->
+<p><!--para 5 -->
The result of the logical negation operator ! is 0 if the value of its operand compares
unequal to 0, 1 if the value of its operand compares equal to 0. The result has type int.
The expression !E is equivalent to (0==E).
-<!--page 108 indent 4-->
+<!--page 108 -->
<a name="6.5.3.4" href="#6.5.3.4"><h5>6.5.3.4 The sizeof and alignof operators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The sizeof operator shall not be applied to an expression that has function type or an
incomplete type, to the parenthesized name of such a type, or to an expression that
designates a bit-field member. The alignof operator shall not be applied to a function
type or an incomplete type.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sizeof operator yields the size (in bytes) of its operand, which may be an
expression or the parenthesized name of a type. The size is determined from the type of
the operand. The result is an integer. If the type of the operand is a variable length array
type, the operand is evaluated; otherwise, the operand is not evaluated and the result is an
integer constant.
-<p><!--para 3-->
+<p><!--para 3 -->
The alignof operator yields the alignment requirement of its operand type. The result
is an integer constant. When applied to an array type, the result is the alignment
requirement of the element type.
-<p><!--para 4-->
+<p><!--para 4 -->
When sizeof is 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.<sup><a href="#note103"><b>103)</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.
-<p><!--para 5-->
+<p><!--para 5 -->
The value of the result of both operators is implementation-defined, and its type (an
unsigned integer type) is size_t, defined in <a href="#7.19"><stddef.h></a> (and other headers).
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 1 A principal use of the sizeof operator is in communication with routines such as storage
allocators and I/O systems. A storage-allocation function might accept a size (in bytes) of an object to
allocate and return a pointer to void. For example:
The implementation of the alloc function should ensure that its return value is aligned suitably for
conversion to a pointer to double.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 2 Another use of the sizeof operator is to compute the number of elements in an array:
<pre>
sizeof array / sizeof array[0]</pre>
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 3 In this example, the size of a variable length array is computed and returned from a
function:
<pre>
-<!--page 109 indent 4-->
+<!--page 109 -->
<pre>
size_t fsize3(int n)
{
<a name="6.5.4" href="#6.5.4"><h4>6.5.4 Cast operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
cast-expression:
unary-expression
( type-name ) cast-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Unless the type name specifies a void type, the type name shall specify atomic, qualified,
or unqualified scalar type, and the operand shall have scalar type.
-<p><!--para 3-->
+<p><!--para 3 -->
Conversions that involve pointers, other than where permitted by the constraints of
<a href="#6.5.16.1">6.5.16.1</a>, shall be specified by means of an explicit cast.
-<p><!--para 4-->
+<p><!--para 4 -->
A pointer type shall not be converted to any floating type. A floating type shall not be
converted to any pointer type.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
Preceding an expression by a parenthesized type name converts the value of the
expression to the named type. This construction is called a cast.<sup><a href="#note104"><b>104)</b></a></sup> A cast that specifies
no conversion has no effect on the type or value of an expression.
-<p><!--para 6-->
+<p><!--para 6 -->
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
type of the expression is the same as the named type and removes any extra range and
<p><b> Forward references</b>: equality operators (<a href="#6.5.9">6.5.9</a>), function declarators (including
prototypes) (<a href="#6.7.6.3">6.7.6.3</a>), simple assignment (<a href="#6.5.16.1">6.5.16.1</a>), type names (<a href="#6.7.7">6.7.7</a>).
-<!--page 110 indent 4-->
+<!--page 110 -->
<h6>footnotes</h6>
<p><small><a name="note104" href="#note104">104)</a> A cast does not yield an lvalue. Thus, a cast to a qualified type has the same effect as a cast to the
<a name="6.5.5" href="#6.5.5"><h4>6.5.5 Multiplicative operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
multiplicative-expression:
cast-expression
multiplicative-expression / cast-expression
multiplicative-expression % cast-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have arithmetic type. The operands of the % operator shall
have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the binary * operator is the product of the operands.
-<p><!--para 5-->
+<p><!--para 5 -->
The result of the / operator is the quotient from the division of the first operand by the
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.
-<p><!--para 6-->
+<p><!--para 6 -->
When integers are divided, the result of the / operator is the algebraic quotient with any
fractional part discarded.<sup><a href="#note105"><b>105)</b></a></sup> If the quotient a/b is representable, the expression
(a/b)*b + a%b shall equal a; otherwise, the behavior of both a/b and a%b is
<a name="6.5.6" href="#6.5.6"><h4>6.5.6 Additive operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
additive-expression:
multiplicative-expression
additive-expression + multiplicative-expression
additive-expression - multiplicative-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
For addition, either both operands shall have arithmetic type, or one operand shall be a
pointer to a complete object type and the other shall have integer type. (Incrementing is
equivalent to adding 1.)
-<p><!--para 3-->
+<p><!--para 3 -->
For subtraction, one of the following shall hold:
-<!--page 111 indent 4-->
+<!--page 111 -->
<ul>
<li> both operands have arithmetic type;
<li> both operands are pointers to qualified or unqualified versions of compatible complete
</ul>
(Decrementing is equivalent to subtracting 1.)
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If both operands have arithmetic type, the usual arithmetic conversions are performed on
them.
-<p><!--para 5-->
+<p><!--para 5 -->
The result of the binary + operator is the sum of the operands.
-<p><!--para 6-->
+<p><!--para 6 -->
The result of the binary - operator is the difference resulting from the subtraction of the
second operand from the first.
-<p><!--para 7-->
+<p><!--para 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.
-<p><!--para 8-->
+<p><!--para 8 -->
When an expression that has integer type is added to or subtracted from a pointer, the
result has the type of the pointer operand. If the pointer operand points to an element of
an array object, and the array is large enough, the result points to an element offset from
element of the array object, the evaluation shall not produce an overflow; otherwise, the
behavior is undefined. If the result points one past the last element of the array object, it
shall not be used as the operand of a unary * operator that is evaluated.
-<p><!--para 9-->
+<p><!--para 9 -->
When two pointers are subtracted, both shall point to elements of the same array object,
or one past the last element of the array object; the result is the difference of the
subscripts of the two array elements. The size of the result is implementation-defined,
If the result is not representable in an object of that type, the behavior is undefined. In
other words, if the expressions P and Q point to, respectively, the i-th and j-th elements of
an array object, the expression (P)-(Q) has the value i-j provided the value fits in an
-<!--page 112 indent 5-->
+<!--page 112 -->
object of type ptrdiff_t. Moreover, if the expression P points either to an element of
an array object or one past the last element of an array object, and the expression Q points
to the last element of the same array object, the expression ((Q)+1)-(P) has the same
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.<sup><a href="#note106"><b>106)</b></a></sup>
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE Pointer arithmetic is well defined with pointers to variable length array types.
-<p><!--para 11-->
+<p><!--para 11 -->
<pre>
{
int n = 4, m = 3;
<a name="6.5.7" href="#6.5.7"><h4>6.5.7 Bitwise shift operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
shift-expression:
additive-expression
shift-expression << additive-expression
shift-expression >> additive-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The integer promotions are performed on each of the operands. The type of the result is
that of the promoted left operand. If the value of the right operand is negative or is
-<!--page 113 indent 4-->
+<!--page 113 -->
greater than or equal to the width of the promoted left operand, the behavior is undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated bits are filled with
zeros. If E1 has an unsigned type, the value of the result is E1 x 2E2 , reduced modulo
one more than the maximum value representable in the result type. If E1 has a signed
type and nonnegative value, and E1 x 2E2 is representable in the result type, then that is
the resulting value; otherwise, the behavior is undefined.
-<p><!--para 5-->
+<p><!--para 5 -->
The result of E1 >> E2 is E1 right-shifted E2 bit positions. If E1 has an unsigned type
or if E1 has a signed type and a nonnegative value, the value of the result is the integral
part of the quotient of E1 / 2E2 . If E1 has a signed type and a negative value, the
<a name="6.5.8" href="#6.5.8"><h4>6.5.8 Relational operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
relational-expression:
shift-expression
relational-expression <= shift-expression
relational-expression >= shift-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
One of the following shall hold:
<ul>
<li> both operands have real type; or *
types.
</ul>
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If both of the operands have arithmetic type, the usual arithmetic conversions are
performed.
-<p><!--para 4-->
+<p><!--para 4 -->
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.
-<p><!--para 5-->
+<p><!--para 5 -->
When two pointers are compared, the result depends on the relative locations in the
address space of the objects pointed to. If two pointers to object types both point to the
same object, or both point one past the last element of the same array object, they
pointers to structure members declared later compare greater than pointers to members
declared earlier in the structure, and pointers to array elements with larger subscript
values compare greater than pointers to elements of the same array with lower subscript
-<!--page 114 indent 4-->
+<!--page 114 -->
values. All pointers to members of the same union object compare equal. If the
expression P points to an element of an array object and the expression Q points to the
last element of the same array object, the pointer expression Q+1 compares greater than
P. In all other cases, the behavior is undefined.
-<p><!--para 6-->
+<p><!--para 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.<sup><a href="#note107"><b>107)</b></a></sup> The result has type int.
<a name="6.5.9" href="#6.5.9"><h4>6.5.9 Equality operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
equality-expression:
relational-expression
equality-expression == relational-expression
equality-expression != relational-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
One of the following shall hold:
<ul>
<li> both operands have arithmetic type;
<li> one operand is a pointer and the other is a null pointer constant.
</ul>
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The == (equal to) and != (not equal to) operators are analogous to the relational
operators except for their lower precedence.<sup><a href="#note108"><b>108)</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.
-<p><!--para 4-->
+<p><!--para 4 -->
If both of the operands have arithmetic type, the usual arithmetic conversions are
performed. Values of complex types are equal if and only if both their real parts are equal
and also their imaginary parts are equal. Any two values of arithmetic types from
-<!--page 115 indent 4-->
-<p><!--para 5-->
+<!--page 115 -->
+<p><!--para 5 -->
Otherwise, at least one operand is a pointer. If one operand is a pointer and the other is a
null pointer constant, the null pointer constant is converted to the type of the pointer. If
one operand is a pointer to an object type and the other is a pointer to a qualified or
unqualified version of void, the former is converted to the type of the latter.
-<p><!--para 6-->
+<p><!--para 6 -->
Two pointers compare equal if and only if both are null pointers, both are pointers to the
same object (including a pointer to an object and a subobject at its beginning) or function,
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.<sup><a href="#note109"><b>109)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 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.
<a name="6.5.10" href="#6.5.10"><h4>6.5.10 Bitwise AND operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
AND-expression:
equality-expression
AND-expression & equality-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the binary & operator is the bitwise AND of the operands (that is, each bit in
the result is set if and only if each of the corresponding bits in the converted operands is
set).
-<!--page 116 indent 4-->
+<!--page 116 -->
<a name="6.5.11" href="#6.5.11"><h4>6.5.11 Bitwise exclusive OR operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
exclusive-OR-expression:
AND-expression
exclusive-OR-expression ^ AND-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the ^ operator is the bitwise exclusive OR of the operands (that is, each bit
in the result is set if and only if exactly one of the corresponding bits in the converted
operands is set).
<a name="6.5.12" href="#6.5.12"><h4>6.5.12 Bitwise inclusive OR operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
inclusive-OR-expression:
exclusive-OR-expression
inclusive-OR-expression | exclusive-OR-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have integer type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The usual arithmetic conversions are performed on the operands.
-<p><!--para 4-->
+<p><!--para 4 -->
The result of the | operator is the bitwise inclusive OR of the operands (that is, each bit in
the result is set if and only if at least one of the corresponding bits in the converted
operands is set).
-<!--page 117 indent 4-->
+<!--page 117 -->
<a name="6.5.13" href="#6.5.13"><h4>6.5.13 Logical AND operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
logical-AND-expression:
inclusive-OR-expression
logical-AND-expression && inclusive-OR-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have scalar type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The && operator shall yield 1 if both of its operands compare unequal to 0; otherwise, it
yields 0. The result has type int.
-<p><!--para 4-->
+<p><!--para 4 -->
Unlike the bitwise binary & operator, the && operator guarantees left-to-right evaluation;
if the second operand is evaluated, there is a sequence point between the evaluations of
the first and second operands. If the first operand compares equal to 0, the second
<a name="6.5.14" href="#6.5.14"><h4>6.5.14 Logical OR operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
logical-OR-expression:
logical-AND-expression
logical-OR-expression || logical-AND-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the operands shall have scalar type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The || operator shall yield 1 if either of its operands compare unequal to 0; otherwise, it
yields 0. The result has type int.
-<p><!--para 4-->
+<p><!--para 4 -->
Unlike the bitwise | operator, the || operator guarantees left-to-right evaluation; if the
second operand is evaluated, there is a sequence point between the evaluations of the first
and second operands. If the first operand compares unequal to 0, the second operand is
not evaluated.
-<!--page 118 indent 4-->
+<!--page 118 -->
<a name="6.5.15" href="#6.5.15"><h4>6.5.15 Conditional operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
conditional-expression:
logical-OR-expression
logical-OR-expression ? expression : conditional-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The first operand shall have scalar type.
-<p><!--para 3-->
+<p><!--para 3 -->
One of the following shall hold for the second and third operands:
<ul>
<li> both operands have arithmetic type;
unqualified version of void.
</ul>
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The first operand is evaluated; there is a sequence point between its evaluation and the
evaluation of the second or third operand (whichever is evaluated). 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.<sup><a href="#note110"><b>110)</b></a></sup> *
-<p><!--para 5-->
+<p><!--para 5 -->
If both the second and third operands have arithmetic type, the result type that would be
determined by the usual arithmetic conversions, were they applied to those two operands,
is the type of the result. If both the operands have structure or union type, the result has
that type. If both operands have void type, the result has void type.
-<p><!--para 6-->
+<p><!--para 6 -->
If both the second and third operands are pointers or one is a null pointer constant and the
other is a pointer, the result type is a pointer to a type qualified with all the type qualifiers
of the types referenced by both operands. Furthermore, if both operands are pointers to
is a pointer to void or a qualified version of void, in which case the result type is a
pointer to an appropriately qualified version of void.
-<!--page 119 indent 4-->
-<p><!--para 7-->
+<!--page 119 -->
+<p><!--para 7 -->
EXAMPLE The common type that results when the second and third operands are pointers is determined
in two independent stages. The appropriate qualifiers, for example, do not depend on whether the two
pointers have compatible types.
-<p><!--para 8-->
+<p><!--para 8 -->
Given the declarations
<pre>
const void *c_vp;
<a name="6.5.16" href="#6.5.16"><h4>6.5.16 Assignment operators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
assignment-expression:
conditional-expression
assignment-operator: one of
= *= /= %= += -= <<= >>= &= ^= |=</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An assignment operator shall have a modifiable lvalue as its left operand.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
An assignment operator stores a value in the object designated by the left operand. An
assignment expression has the value of the left operand after the assignment,<sup><a href="#note111"><b>111)</b></a></sup> but is not
an lvalue. The type of an assignment expression is the type the left operand would have
-<!--page 120 indent 4-->
+<!--page 120 -->
<h6>footnotes</h6>
<p><small><a name="note111" href="#note111">111)</a> The implementation is permitted to read the object to determine the value but is not required to, even
<a name="6.5.16.1" href="#6.5.16.1"><h5>6.5.16.1 Simple assignment</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
One of the following shall hold:<sup><a href="#note112"><b>112)</b></a></sup>
<ul>
<li> the left operand has atomic, qualified, or unqualified arithmetic type, and the right has
pointer.
</ul>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
In simple assignment (=), the value of the right operand is converted to the type of the
assignment expression and replaces the value stored in the object designated by the left
operand.
-<p><!--para 3-->
+<p><!--para 3 -->
If the value being stored in an object is read from another object that overlaps in any way
the storage of the first object, then the overlap shall be exact and the two objects shall
have qualified or unqualified versions of a compatible type; otherwise, the behavior is
undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE 1 In the program fragment
-<!--page 121 indent 4-->
+<!--page 121 -->
<pre>
int f(void);
char c;
negative, so the operands of the comparison can never compare equal. Therefore, for full portability, the
variable c should be declared as int.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 2 In the fragment:
<pre>
char c;
of the expression enclosed in parentheses is then converted to the type of the outer assignment expression,
that is, long int type.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 3 Consider the fragment:
<pre>
const char **cpp;
<a name="6.5.16.2" href="#6.5.16.2"><h5>6.5.16.2 Compound assignment</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
For the operators += and -= only, either the left operand shall be an atomic, qualified, or
unqualified pointer to a complete object type, and the right shall have integer type; or the
left operand shall have atomic, qualified, or unqualified arithmetic type, and the right
shall have arithmetic type.
-<p><!--para 2-->
+<p><!--para 2 -->
For the other operators, the left operand shall have atomic, qualified, or unqualified
arithmetic type, and (considering the type the left operand would have after lvalue
conversion) each operand shall have arithmetic type consistent with those allowed by the
corresponding binary operator.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
A compound assignment of the form E1 op = E2 is equivalent to the simple assignment
expression E1 = E1 op (E2), except that the lvalue E1 is evaluated only once, and with
respect to an indeterminately-sequenced function call, the operation of a compound
-<!--page 122 indent 4-->
+<!--page 122 -->
assignment is a single evaluation. If E1 has an atomic type, compound assignment is a
read-modify-write operation with memory_order_seq_cst memory order
semantics.<sup><a href="#note113"><b>113)</b></a></sup>
<a name="6.5.17" href="#6.5.17"><h4>6.5.17 Comma operator</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
expression:
assignment-expression
expression , assignment-expression</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The left operand of a comma operator is evaluated as a void expression; there is a
sequence point between its evaluation and that of the right operand. Then the right
operand is evaluated; the result has its type and value.<sup><a href="#note114"><b>114)</b></a></sup> *
-<p><!--para 3-->
+<p><!--para 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
of initializers). On the other hand, it can be used within a parenthesized expression or within the second
-<!--page 123 indent 4-->
+<!--page 123 -->
<h6>footnotes</h6>
<p><small><a name="note114" href="#note114">114)</a> A comma operator does not yield an lvalue.
<a name="6.6" href="#6.6"><h3>6.6 Constant expressions</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
constant-expression:
conditional-expression</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A constant expression can be evaluated during translation rather than runtime, and
accordingly may be used in any place that a constant may be.
<h6>Constraints</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Constant expressions shall not contain assignment, increment, decrement, function-call,
or comma operators, except when they are contained within a subexpression that is not
evaluated.<sup><a href="#note115"><b>115)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
Each constant expression shall evaluate to a constant that is in the range of representable
values for its type.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
An expression that evaluates to a constant is required in several contexts. If a floating
expression is evaluated in the translation environment, the arithmetic precision and range
shall be at least as great as if the expression were being evaluated in the execution
environment.<sup><a href="#note116"><b>116)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 6 -->
An integer constant expression<sup><a href="#note117"><b>117)</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
convert arithmetic types to integer types, except as part of an operand to the sizeof
operator.
-<p><!--para 7-->
+<p><!--para 7 -->
More latitude is permitted for constant expressions in initializers. Such a constant
expression shall be, or evaluate to, one of the following:
<ul>
-<!--page 124 indent 5-->
+<!--page 124 -->
<li> a null pointer constant,
<li> an address constant, or
<li> an address constant for a complete object type plus or minus an integer constant
expression.
</ul>
-<p><!--para 8-->
+<p><!--para 8 -->
An arithmetic constant expression shall have arithmetic type and shall only have
operands that are integer constants, floating constants, enumeration constants, character
constants, and sizeof expressions. Cast operators in an arithmetic constant expression
shall only convert arithmetic types to arithmetic types, except as part of an operand to a
sizeof operator whose result is an integer constant.
-<p><!--para 9-->
+<p><!--para 9 -->
An address constant is a null pointer, a pointer to an lvalue designating an object of static
storage duration, or a pointer to a function designator; it shall be created explicitly using
the unary & operator or an integer constant cast to pointer type, or implicitly by the use of
and -> operators, the address & and indirection * unary operators, and pointer casts may
be used in the creation of an address constant, but the value of an object shall not be
accessed by use of these operators.
-<p><!--para 10-->
+<p><!--para 10 -->
An implementation may accept other forms of constant expressions.
-<p><!--para 11-->
+<p><!--para 11 -->
The semantic rules for the evaluation of a constant expression are the same as for
nonconstant expressions.<sup><a href="#note118"><b>118)</b></a></sup>
<p><b> Forward references</b>: array declarators (<a href="#6.7.6.2">6.7.6.2</a>), initialization (<a href="#6.7.9">6.7.9</a>).
-<!--page 125 indent 4-->
+<!--page 125 -->
<h6>footnotes</h6>
<p><small><a name="note115" href="#note115">115)</a> The operand of a sizeof operator is usually not evaluated (<a href="#6.5.3.4">6.5.3.4</a>).
<a name="6.7" href="#6.7"><h3>6.7 Declarations</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
declaration:
declaration-specifiers init-declarator-listopt ;
declarator
declarator = initializer</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A declaration other than a static_assert declaration shall declare at least a declarator
(other than the parameters of a function or the members of a structure or union), a tag, or
the members of an enumeration.
-<p><!--para 3-->
+<p><!--para 3 -->
If an identifier has no linkage, there shall be no more than one declaration of the identifier
(in a declarator or type specifier) with the same scope and in the same name space, except
that a typedef name can be redefined to denote the same type as it currently does and tags
may be redeclared as specified in <a href="#6.7.2.3">6.7.2.3</a>.
-<p><!--para 4-->
+<p><!--para 4 -->
All declarations in the same scope that refer to the same object or function shall specify
compatible types.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
A declaration specifies the interpretation and attributes of a set of identifiers. A definition
of an identifier is a declaration for that identifier that:
<ul>
-<!--page 126 indent 4-->
+<!--page 126 -->
<li> for an enumeration constant or typedef name, is the (only) declaration of the
identifier.
</ul>
-<p><!--para 6-->
+<p><!--para 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
additional type information, or an initializer, or both. The declarators contain the
identifiers (if any) being declared.
-<p><!--para 7-->
+<p><!--para 7 -->
If an identifier for an object is declared with no linkage, the type for the object shall be
complete by the end of its declarator, or by the end of its init-declarator if it has an
initializer; in the case of function parameters (including in prototypes), it is the adjusted
<a name="6.7.1" href="#6.7.1"><h4>6.7.1 Storage-class specifiers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
storage-class-specifier:
typedef
auto
register</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
At most, one storage-class specifier may be given in the declaration specifiers in a
declaration, except that _Thread_local may appear with static or extern.<sup><a href="#note120"><b>120)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
In the declaration of an object with block scope, if the declaration specifiers include
_Thread_local, they shall also include either static or extern. If
_Thread_local appears in any declaration of an object, it shall be present in every
declaration of that object.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The typedef specifier is called a ''storage-class specifier'' for syntactic convenience
only; it is discussed in <a href="#6.7.8">6.7.8</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>.
-<!--page 127 indent 4-->
-<p><!--para 5-->
+<!--page 127 -->
+<p><!--para 5 -->
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.<sup><a href="#note121"><b>121)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 6 -->
The declaration of an identifier for a function that has block scope shall have no explicit
storage-class specifier other than extern.
-<p><!--para 7-->
+<p><!--para 7 -->
If an aggregate or union object is declared with a storage-class specifier other than
typedef, the properties resulting from the storage-class specifier, except with respect to
linkage, also apply to the members of the object, and so on recursively for any aggregate
<a name="6.7.2" href="#6.7.2"><h4>6.7.2 Type specifiers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
type-specifier:
void
enum-specifier
typedef-name</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
At least one type specifier shall be given in the declaration specifiers in each declaration,
and in the specifier-qualifier list in each struct declaration and type name. Each list of
-<!--page 128 indent 4-->
+<!--page 128 -->
type specifiers shall be one of the following multisets (delimited by commas, when there
is more than one multiset per item); the type specifiers may occur in any order, possibly
intermixed with the other declaration specifiers.
<li> enum specifier
<li> typedef name
</ul>
-<p><!--para 3-->
+<p><!--para 3 -->
The type specifier _Complex shall not be used if the implementation does not support
complex types (see <a href="#6.10.8.3">6.10.8.3</a>).
-<!--page 129 indent 4-->
+<!--page 129 -->
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
Specifiers for structures, unions, enumerations, and atomic types are discussed in <a href="#6.7.2.1">6.7.2.1</a>
through <a href="#6.7.2.4">6.7.2.4</a>. Declarations of typedef names are discussed in <a href="#6.7.8">6.7.8</a>. The
characteristics of the other types are discussed in <a href="#6.2.5">6.2.5</a>.
-<p><!--para 5-->
+<p><!--para 5 -->
Each of the comma-separated multisets designates the same type, except that for bit-
fields, it is implementation-defined whether the specifier int designates the same type as
signed int or the same type as unsigned int.
<a name="6.7.2.1" href="#6.7.2.1"><h5>6.7.2.1 Structure and union specifiers</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
struct-or-union-specifier:
struct-or-union identifieropt { struct-declaration-list }
declarator
declaratoropt : constant-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A struct-declaration that does not declare an anonymous structure or anonymous union
shall contain a struct-declarator-list.
-<!--page 130 indent 5-->
-<p><!--para 3-->
+<!--page 130 -->
+<p><!--para 3 -->
A structure or union shall not contain a member with incomplete or function type (hence,
a structure shall not contain an instance of itself, but may contain a pointer to an instance
of itself), except that the last member of a structure with more than one named member
may have incomplete array type; such a structure (and any union containing, possibly
recursively, a member that is such a structure) shall not be a member of a structure or an
element of an array.
-<p><!--para 4-->
+<p><!--para 4 -->
The expression that specifies the width of a bit-field shall be an integer constant
expression with a nonnegative value that does not exceed the width of an object of the
type that would be specified were the colon and expression omitted.<sup><a href="#note122"><b>122)</b></a></sup> If the value is
zero, the declaration shall have no declarator.
-<p><!--para 5-->
+<p><!--para 5 -->
A bit-field shall have a type that is a qualified or unqualified version of _Bool, signed
int, unsigned int, or some other implementation-defined type. It is
implementation-defined whether atomic types are permitted.
<h6>Semantics</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
As discussed in <a href="#6.2.5">6.2.5</a>, a structure is a type consisting of a sequence of members, whose
storage is allocated in an ordered sequence, and a union is a type consisting of a sequence
of members whose storage overlap.
-<p><!--para 7-->
+<p><!--para 7 -->
Structure and union specifiers have the same form. The keywords struct and union
indicate that the type being specified is, respectively, a structure type or a union type.
-<p><!--para 8-->
+<p><!--para 8 -->
The presence of a struct-declaration-list in a struct-or-union-specifier declares a new type,
within a translation unit. The struct-declaration-list is a sequence of declarations for the
members of the structure or union. If the struct-declaration-list contains no named
members, no anonymous structures, and no anonymous unions, the behavior is undefined.
The type is incomplete until immediately after the } that terminates the list, and complete
thereafter.
-<p><!--para 9-->
+<p><!--para 9 -->
A member of a structure or union may have any complete object type other than a
variably modified type.<sup><a href="#note123"><b>123)</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="#note124"><b>124)</b></a></sup> its width is preceded by a colon.
-<p><!--para 10-->
+<p><!--para 10 -->
A bit-field is interpreted as having a signed or unsigned integer type consisting of the
specified number of bits.<sup><a href="#note125"><b>125)</b></a></sup> If the value 0 or 1 is stored into a nonzero-width bit-field of
-<!--page 131 indent 5-->
+<!--page 131 -->
type _Bool, the value of the bit-field shall compare equal to the value stored; a _Bool
bit-field has the semantics of a _Bool.
-<p><!--para 11-->
+<p><!--para 11 -->
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
structure shall be packed into adjacent bits of the same unit. If insufficient space remains,
implementation-defined. The order of allocation of bit-fields within a unit (high-order to
low-order or low-order to high-order) is implementation-defined. The alignment of the
addressable storage unit is unspecified.
-<p><!--para 12-->
+<p><!--para 12 -->
A bit-field declaration with no declarator, but only a colon and a width, indicates an
unnamed bit-field.<sup><a href="#note126"><b>126)</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.
-<p><!--para 13-->
+<p><!--para 13 -->
An unnamed member of structure type with no tag is called an anonymous structure; an
unnamed member of union type with no tag is called an anonymous union. The members
of an anonymous structure or union are considered to be members of the containing
structure or union. This applies recursively if the containing structure or union is also
anonymous.
-<p><!--para 14-->
+<p><!--para 14 -->
Each non-bit-field member of a structure or union object is aligned in an implementation-
defined manner appropriate to its type.
-<p><!--para 15-->
+<p><!--para 15 -->
Within a structure object, the non-bit-field members and the units in which bit-fields
reside have addresses that increase in the order in which they are declared. A pointer to a
structure object, suitably converted, points to its initial member (or if that member is a
bit-field, then to the unit in which it resides), and vice versa. There may be unnamed
padding within a structure object, but not at its beginning.
-<p><!--para 16-->
+<p><!--para 16 -->
The size of a union is sufficient to contain the largest of its members. The value of at
most one of the members can be stored in a union object at any time. A pointer to a
union object, suitably converted, points to each of its members (or if a member is a bit-
field, then to the unit in which it resides), and vice versa.
-<p><!--para 17-->
+<p><!--para 17 -->
There may be unnamed padding at the end of a structure or union.
-<p><!--para 18-->
+<p><!--para 18 -->
As a special case, the last element of a structure with more than one named member may
have an incomplete array type; this is called a flexible array member. In most situations,
-<!--page 132 indent 5-->
+<!--page 132 -->
the flexible array member is ignored. In particular, the size of the structure is as if the
flexible array member were omitted except that it may have more trailing padding than
the omission would imply. However, when a . (or ->) operator has a left operand that is
from that of the replacement array. If this array would have no elements, it behaves as if
it had one element but the behavior is undefined if any attempt is made to access that
element or to generate a pointer one past it.
-<p><!--para 19-->
+<p><!--para 19 -->
EXAMPLE 1 The following illustrates anonymous structures and unions:
<pre>
struct v {
v1.k = 3; // invalid: inner structure is not anonymous
v1.w.k = 5; // valid</pre>
-<p><!--para 20-->
+<p><!--para 20 -->
EXAMPLE 2 After the declaration:
<pre>
struct s { int n; double d[]; };</pre>
struct { int n; double d[m]; } *p;</pre>
(there are circumstances in which this equivalence is broken; in particular, the offsets of member d might
not be the same).
-<p><!--para 21-->
+<p><!--para 21 -->
Following the above declaration:
<pre>
struct s t1 = { 0 }; // valid
sizeof (struct s) >= offsetof(struct s, d) + sizeof (double)</pre>
in which case the assignment would be legitimate. Nevertheless, it cannot appear in strictly conforming
code.
-<!--page 133 indent 5-->
-<p><!--para 22-->
+<!--page 133 -->
+<p><!--para 22 -->
After the further declaration:
<pre>
struct ss { int n; };</pre>
sizeof (struct s) >= sizeof (struct ss)
sizeof (struct s) >= offsetof(struct s, d)</pre>
are always equal to 1.
-<p><!--para 23-->
+<p><!--para 23 -->
If sizeof (double) is 8, then after the following code is executed:
<pre>
struct s *s1;
s2 = malloc(sizeof (struct s) + 46);</pre>
and assuming that the calls to malloc succeed, the objects pointed to by s1 and s2 behave, for most
purposes, as if the identifiers had been declared as:
-<p><!--para 24-->
+<p><!--para 24 -->
<pre>
struct { int n; double d[8]; } *s1;
struct { int n; double d[5]; } *s2;</pre>
<pre>
struct { int n; double d[1]; } *s1, *s2;</pre>
and:
-<p><!--para 25-->
+<p><!--para 25 -->
<pre>
double *dp;
dp = &(s1->d[0]); // valid
of the structure, they might be copied or simply overwritten with indeterminate values.
<p><b> Forward references</b>: declarators (<a href="#6.7.6">6.7.6</a>), tags (<a href="#6.7.2.3">6.7.2.3</a>).
-<!--page 134 indent 4-->
+<!--page 134 -->
<h6>footnotes</h6>
<p><small><a name="note122" href="#note122">122)</a> While the number of bits in a _Bool object is at least CHAR_BIT, the width (number of sign and
<a name="6.7.2.2" href="#6.7.2.2"><h5>6.7.2.2 Enumeration specifiers</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
enum-specifier:
enum identifieropt { enumerator-list }
enumeration-constant
enumeration-constant = constant-expression</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The expression that defines the value of an enumeration constant shall be an integer
constant expression that has a value representable as an int.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The identifiers in an enumerator list are declared as constants that have type int and
may appear wherever such are permitted.<sup><a href="#note127"><b>127)</b></a></sup> An enumerator with = defines its
enumeration constant as the value of the constant expression. If the first enumerator has
adding 1 to the value of the previous enumeration constant. (The use of enumerators with
= 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.
-<p><!--para 4-->
+<p><!--para 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,<sup><a href="#note128"><b>128)</b></a></sup> but shall be
capable of representing the values of all the members of the enumeration. The
-<!--page 135 indent 4-->
-<p><!--para 5-->
+<!--page 135 -->
+<p><!--para 5 -->
EXAMPLE The following fragment:
<pre>
enum hue { chartreuse, burgundy, claret=20, winedark };
<a name="6.7.2.3" href="#6.7.2.3"><h5>6.7.2.3 Tags</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A specific type shall have its content defined at most once.
-<p><!--para 2-->
+<p><!--para 2 -->
Where two declarations that use the same tag declare the same type, they shall both use
the same choice of struct, union, or enum.
-<p><!--para 3-->
+<p><!--para 3 -->
A type specifier of the form
<pre>
enum identifier</pre>
without an enumerator list shall only appear after the type it specifies is complete.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
All declarations of structure, union, or enumerated types that have the same scope and
use the same tag declare the same type. Irrespective of whether there is a tag or what
other declarations of the type are in the same translation unit, the type is incomplete<sup><a href="#note129"><b>129)</b></a></sup>
until immediately after the closing brace of the list defining the content, and complete
thereafter.
-<p><!--para 5-->
+<p><!--para 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
enumerated type which does not include a tag declares a distinct type.
-<p><!--para 6-->
+<p><!--para 6 -->
A type specifier of the form
-<!--page 136 indent 5-->
+<!--page 136 -->
<pre>
struct-or-union identifieropt { struct-declaration-list }</pre>
or
declares a structure, union, or enumerated type. The list defines the structure content,
union content, or enumeration content. If an identifier is provided,<sup><a href="#note130"><b>130)</b></a></sup> the type specifier
also declares the identifier to be the tag of that type.
-<p><!--para 7-->
+<p><!--para 7 -->
A declaration of the form
<pre>
struct-or-union identifier ;</pre>
specifies a structure or union type and declares the identifier as a tag of that type.<sup><a href="#note131"><b>131)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
If a type specifier of the form
<pre>
struct-or-union identifier</pre>
occurs other than as part of one of the above forms, and no other declaration of the
identifier as a tag is visible, then it declares an incomplete structure or union type, and
declares the identifier as the tag of that type.131)
-<p><!--para 9-->
+<p><!--para 9 -->
If a type specifier of the form
<pre>
struct-or-union identifier</pre>
occurs other than as part of one of the above forms, and a declaration of the identifier as a
tag is visible, then it specifies the same type as that other declaration, and does not
redeclare the tag.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 1 This mechanism allows declaration of a self-referential structure.
<pre>
struct tnode {
-<!--page 137 indent 5-->
+<!--page 137 -->
<pre>
struct tnode s, *sp;</pre>
declares s to be an object of the given type and sp to be a pointer to an object of the given type. With
these declarations, the expression sp->left refers to the left struct tnode pointer of the object to
which sp points; the expression s.right->count designates the count member of the right struct
tnode pointed to from s.
-<p><!--para 11-->
+<p><!--para 11 -->
The following alternative formulation uses the typedef mechanism:
<pre>
typedef struct tnode TNODE;
};
TNODE s, *sp;</pre>
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE 2 To illustrate the use of prior declaration of a tag to specify a pair of mutually referential
structures, the declarations
<pre>
<a name="6.7.2.4" href="#6.7.2.4"><h5>6.7.2.4 Atomic type specifiers</h5></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
atomic-type-specifier:
_Atomic ( type-name )</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Atomic type specifiers shall not be used if the implementation does not support atomic
types (see <a href="#6.10.8.3">6.10.8.3</a>).
-<p><!--para 3-->
+<p><!--para 3 -->
The type name in an atomic type specifier shall not refer to an array type, a function type,
an atomic type, or a qualified type.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The properties associated with atomic types are meaningful only for expressions that are
lvalues. If the _Atomic keyword is immediately followed by a left parenthesis, it is
interpreted as a type specifier (with a type name), not as a type qualifier.
-<!--page 138 indent 4-->
+<!--page 138 -->
<a name="6.7.3" href="#6.7.3"><h4>6.7.3 Type qualifiers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
type-qualifier:
const
volatile
_Atomic</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Types other than pointer types whose referenced type is an object type shall not be
restrict-qualified.
-<p><!--para 3-->
+<p><!--para 3 -->
The type modified by the _Atomic qualifier shall not be an array type or a function
type.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The properties associated with qualified types are meaningful only for expressions that
are lvalues.<sup><a href="#note132"><b>132)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
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. If other qualifiers appear along with the _Atomic qualifier in a specifier-qualifier-
list, the resulting type is the so-qualified atomic type.
-<p><!--para 6-->
+<p><!--para 6 -->
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.<sup><a href="#note133"><b>133)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 7 -->
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,
-<!--page 139 indent 5-->
+<!--page 139 -->
unknown factors mentioned previously.<sup><a href="#note134"><b>134)</b></a></sup> What constitutes an access to an object that
has volatile-qualified type is implementation-defined.
-<p><!--para 8-->
+<p><!--para 8 -->
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.<sup><a href="#note135"><b>135)</b></a></sup> The intended
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).
-<p><!--para 9-->
+<p><!--para 9 -->
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.<sup><a href="#note136"><b>136)</b></a></sup>
-<p><!--para 10-->
+<p><!--para 10 -->
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.
-<p><!--para 11-->
+<p><!--para 11 -->
EXAMPLE 1 An object declared
<pre>
extern const volatile int real_time_clock;</pre>
may be modifiable by hardware, but cannot be assigned to, incremented, or decremented.
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE 2 The following declarations and expressions illustrate the behavior when type qualifiers
modify an aggregate type:
<pre>
-<!--page 140 indent 5-->
-<p><!--para 13-->
+<!--page 140 -->
+<p><!--para 13 -->
EXAMPLE 3 The declaration
<pre>
_Atomic volatile int *p;</pre>
</small>
<a name="6.7.3.1" href="#6.7.3.1"><h5>6.7.3.1 Formal definition of restrict</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Let D be a declaration of an ordinary identifier that provides a means of designating an
object P as a restrict-qualified pointer to type T.
-<p><!--para 2-->
+<p><!--para 2 -->
If D appears inside a block and does not have storage class extern, let B denote the
block. If D appears in the list of parameter declarations of a function definition, let B
denote the associated block. Otherwise, let B denote the block of main (or the block of
whatever function is called at program startup in a freestanding environment).
-<p><!--para 3-->
+<p><!--para 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.<sup><a href="#note137"><b>137)</b></a></sup>
Note that ''based'' is defined only for expressions with pointer types.
-<p><!--para 4-->
+<p><!--para 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),
then the following requirements apply: T shall not be const-qualified. Every other lvalue
object P2, associated with block B2, then either the execution of B2 shall begin before
the execution of B, or the execution of B2 shall end prior to the assignment. If these
requirements are not met, then the behavior is undefined.
-<p><!--para 5-->
+<p><!--para 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
associated with B.
-<p><!--para 6-->
+<p><!--para 6 -->
A translator is free to ignore any or all aliasing implications of uses of restrict.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1 The file scope declarations
<pre>
int * restrict a;
program, then it is never accessed using either of the other two.
-<!--page 141 indent 5-->
-<p><!--para 8-->
+<!--page 141 -->
+<p><!--para 8 -->
EXAMPLE 2 The function parameter declarations in the following example
<pre>
void f(int n, int * restrict p, int * restrict q)
}</pre>
assert that, during each execution of the function, if an object is accessed through one of the pointer
parameters, then it is not also accessed through the other.
-<p><!--para 9-->
+<p><!--para 9 -->
The benefit of the restrict qualifiers is that they enable a translator to make an effective dependence
analysis of function f without examining any of the calls of f in the program. The cost is that the
programmer has to examine all of those calls to ensure that none give undefined behavior. For example, the
f(50, d + 1, d); // undefined behavior
}</pre>
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 3 The function parameter declarations
<pre>
void h(int n, int * restrict p, int * restrict q, int * restrict r)
are disjoint arrays, a call of the form h(100, a, b, b) has defined behavior, because array b is not
modified within function h.
-<p><!--para 11-->
+<p><!--para 11 -->
EXAMPLE 4 The rule limiting assignments between restricted pointers does not distinguish between a
function call and an equivalent nested block. With one exception, only ''outer-to-inner'' assignments
between restricted pointers declared in nested blocks have defined behavior.
-<!--page 142 indent 5-->
-<p><!--para 12-->
+<!--page 142 -->
+<p><!--para 12 -->
<pre>
{
int * restrict p1;
<a name="6.7.4" href="#6.7.4"><h4>6.7.4 Function specifiers</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
function-specifier:
inline
_Noreturn</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Function specifiers shall be used only in the declaration of an identifier for a function.
-<p><!--para 3-->
+<p><!--para 3 -->
An inline definition of a function with external linkage shall not contain a definition of a
modifiable object with static or thread storage duration, and shall not contain a reference
to an identifier with internal linkage.
-<p><!--para 4-->
+<p><!--para 4 -->
In a hosted environment, no function specifier(s) shall appear in a declaration of main.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
A function specifier may appear more than once; the behavior is the same as if it
appeared only once.
-<p><!--para 6-->
+<p><!--para 6 -->
A function declared with an inline function specifier is an inline function. Making a *
function an inline function suggests that calls to the function be as fast as possible.<sup><a href="#note138"><b>138)</b></a></sup>
The extent to which such suggestions are effective is implementation-defined.<sup><a href="#note139"><b>139)</b></a></sup>
-<!--page 143 indent 5-->
-<p><!--para 7-->
+<!--page 143 -->
+<p><!--para 7 -->
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
function specifier, then it shall also be defined in the same translation unit. If all of the
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.<sup><a href="#note140"><b>140)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
A function declared with a _Noreturn function specifier shall not return to its caller.
Recommended practice
-<p><!--para 9-->
+<p><!--para 9 -->
The implementation should produce a diagnostic message for a function declared with a
_Noreturn function specifier that appears to be capable of returning to its caller.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE 1 The declaration of an inline function with external linkage can result in either an external
definition, or a definition available for use only within the translation unit. A file scope declaration with
extern creates an external definition. The following example shows an entire translation unit.
-<p><!--para 11-->
+<p><!--para 11 -->
<pre>
inline double fahr(double t)
{
external definition has to appear in another translation unit (see <a href="#6.9">6.9</a>); the inline definition and the external
definition are distinct and either may be used for the call.
-<p><!--para 12-->
+<p><!--para 12 -->
EXAMPLE 2
-<!--page 144 indent 4-->
+<!--page 144 -->
<pre>
_Noreturn void f () {
abort(); // ok
<a name="6.7.5" href="#6.7.5"><h4>6.7.5 Alignment specifier</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
alignment-specifier:
_Alignas ( type-name )
_Alignas ( constant-expression )</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
An alignment attribute shall not be specified in a declaration of a typedef, or a bit-field, or
a function, or a parameter, or an object declared with the register storage-class
specifier.
-<p><!--para 3-->
+<p><!--para 3 -->
The constant expression shall be an integer constant expression. It shall evaluate to a
valid fundamental alignment, or to a valid extended alignment supported by the
implementation in the context in which it appears, or to zero.
-<p><!--para 4-->
+<p><!--para 4 -->
The combined effect of all alignment attributes in a declaration shall not specify an
alignment that is less strict than the alignment that would otherwise be required for the
type of the object or member being declared.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The first form is equivalent to _Alignas(alignof(type-name)).
-<p><!--para 6-->
+<p><!--para 6 -->
The alignment requirement of the declared object or member is taken to be the specified
alignment. An alignment specification of zero has no effect.<sup><a href="#note141"><b>141)</b></a></sup> When multiple
alignment specifiers occur in a declaration, the effective alignment requirement is the
strictest specified alignment.
-<p><!--para 7-->
+<p><!--para 7 -->
If the definition of an object has an alignment specifier, any other declaration of that
object shall either specify equivalent alignment or have no alignment specifier. If the
definition of an object does not have an alignment specifier, any other declaration of that
-<!--page 145 indent 4-->
+<!--page 145 -->
<h6>footnotes</h6>
<p><small><a name="note141" href="#note141">141)</a> An alignment specification of zero also does not affect other alignment specifications in the same
<a name="6.7.6" href="#6.7.6"><h4>6.7.6 Declarators</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
declarator:
pointeropt direct-declarator
identifier
identifier-list , identifier</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Each declarator declares one identifier, and asserts that when an operand of the same
form as the declarator appears in an expression, it designates a function or object with the
scope, storage duration, and type indicated by the declaration specifiers.
-<p><!--para 3-->
+<p><!--para 3 -->
A full declarator is a declarator that is not part of another declarator. The end of a full
declarator is a sequence point. If, in the nested sequence of declarators in a full
-<!--page 146 indent 4-->
+<!--page 146 -->
declarator, there is a declarator specifying a variable length array type, the type specified
by the full declarator is said to be variably modified. Furthermore, any type derived by
declarator type derivation from a variably modified type is itself variably modified.
-<p><!--para 4-->
+<p><!--para 4 -->
In the following subclauses, consider a declaration
<pre>
T D1</pre>
where T contains the declaration specifiers that specify a type T (such as int) and D1 is
a declarator that contains an identifier ident. The type specified for the identifier ident in
the various forms of declarator is described inductively using this notation.
-<p><!--para 5-->
+<p><!--para 5 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
identifier</pre>
then the type specified for ident is T .
-<p><!--para 6-->
+<p><!--para 6 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
( D )</pre>
parentheses is identical to the unparenthesized declarator, but the binding of complicated
declarators may be altered by parentheses.
Implementation limits
-<p><!--para 7-->
+<p><!--para 7 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, an implementation may limit the number of pointer, array, and
function declarators that modify an arithmetic, structure, union, or void type, either
directly or via one or more typedefs.
<a name="6.7.6.1" href="#6.7.6.1"><h5>6.7.6.1 Pointer declarators</h5></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
If, in the declaration ''T D1'', D1 has the form
<pre>
* type-qualifier-listopt D</pre>
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list type-qualifier-list
pointer to T ''. For each type qualifier in the list, ident is a so-qualified pointer.
-<p><!--para 2-->
+<p><!--para 2 -->
For two pointer types to be compatible, both shall be identically qualified and both shall
be pointers to compatible types.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE The following pair of declarations demonstrates the difference between a ''variable pointer
to a constant value'' and a ''constant pointer to a variable value''.
-<!--page 147 indent 4-->
+<!--page 147 -->
<pre>
const int *ptr_to_constant;
int *const constant_ptr;</pre>
but ptr_to_constant itself may be changed to point to another object. Similarly, the contents of the
int pointed to by constant_ptr may be modified, but constant_ptr itself shall always point to the
same location.
-<p><!--para 4-->
+<p><!--para 4 -->
The declaration of the constant pointer constant_ptr may be clarified by including a definition for the
type ''pointer to int''.
<pre>
<a name="6.7.6.2" href="#6.7.6.2"><h5>6.7.6.2 Array declarators</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
In addition to optional type qualifiers and the keyword static, the [ and ] may delimit
an expression or *. If they delimit an expression (which specifies the size of an array), the
expression shall have an integer type. If the expression is a constant expression, it shall
type. The optional type qualifiers and the keyword static shall appear only in a
declaration of a function parameter with an array type, and then only in the outermost
array type derivation.
-<p><!--para 2-->
+<p><!--para 2 -->
If an identifier is declared as having a variably modified type, it shall be an ordinary
identifier (as defined in <a href="#6.2.3">6.2.3</a>), have no linkage, and have either block scope or function
prototype scope. If an identifier is declared to be an object with static or thread storage
duration, it shall not have a variable length array type.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If, in the declaration ''T D1'', D1 has one of the forms:
<pre>
D[ type-qualifier-listopt assignment-expressionopt ]
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list array of T ''.<sup><a href="#note142"><b>142)</b></a></sup>
(See <a href="#6.7.6.3">6.7.6.3</a> for the meaning of the optional type qualifiers and the keyword static.)
-<p><!--para 4-->
+<p><!--para 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 or type names with function prototype scope;<sup><a href="#note143"><b>143)</b></a></sup>
-<!--page 148 indent 4-->
+<!--page 148 -->
such arrays are nonetheless complete types. If the size is an integer constant expression
and the element type has a known constant size, the array type is not a variable length
array type; otherwise, the array type is a variable length array type. (Variable length
arrays are a conditional feature that implementations need not support; see <a href="#6.10.8.3">6.10.8.3</a>.)
-<p><!--para 5-->
+<p><!--para 5 -->
If the size is an expression that is not an integer constant expression: if it occurs in a
declaration at function prototype scope, it is treated as if it were replaced by *; otherwise,
each time it is evaluated it shall have a value greater than zero. The size of each instance
expression is part of the operand of a sizeof operator and changing the value of the
size expression would not affect the result of the operator, it is unspecified whether or not
the size expression is evaluated.
-<p><!--para 6-->
+<p><!--para 6 -->
For two array types to be compatible, both shall have compatible element types, and if
both size specifiers are present, and are integer constant expressions, then both size
specifiers shall have the same constant value. If the two array types are used in a context
which requires them to be compatible, it is undefined behavior if the two size specifiers
evaluate to unequal values.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1
<pre>
float fa[11], *afp[17];</pre>
declares an array of float numbers and an array of pointers to float numbers.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 2 Note the distinction between the declarations
<pre>
extern int *x;
The first declares x to be a pointer to int; the second declares y to be an array of int of unspecified size
(an incomplete type), the storage for which is defined elsewhere.
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 3 The following declarations demonstrate the compatibility rules for variably modified types.
<pre>
extern int n;
-<!--page 149 indent 5-->
-<p><!--para 10-->
+<!--page 149 -->
+<p><!--para 10 -->
EXAMPLE 4 All declarations of variably modified (VM) types have to be at either block scope or
function prototype scope. Array objects declared with the _Thread_local, static, or extern
storage-class specifier cannot have a variable length array (VLA) type. However, an object declared with
<a name="6.7.6.3" href="#6.7.6.3"><h5>6.7.6.3 Function declarators (including prototypes)</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A function declarator shall not specify a return type that is a function type or an array
type.
-<p><!--para 2-->
+<p><!--para 2 -->
The only storage-class specifier that shall occur in a parameter declaration is register.
-<p><!--para 3-->
+<p><!--para 3 -->
An identifier list in a function declarator that is not part of a definition of that function
shall be empty.
-<p><!--para 4-->
+<p><!--para 4 -->
After adjustment, the parameters in a parameter type list in a function declarator that is
part of a definition of that function shall not have incomplete type.
<h6>Semantics</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
If, in the declaration ''T D1'', D1 has the form
-<!--page 150 indent 5-->
+<!--page 150 -->
<pre>
D( parameter-type-list )</pre>
or
and the type specified for ident in the declaration ''T D'' is ''derived-declarator-type-list
T '', then the type specified for ident is ''derived-declarator-type-list function returning
T ''.
-<p><!--para 6-->
+<p><!--para 6 -->
A parameter type list specifies the types of, and may declare identifiers for, the
parameters of the function.
-<p><!--para 7-->
+<p><!--para 7 -->
A declaration of a parameter as ''array of type'' shall be adjusted to ''qualified pointer to
type'', where the type qualifiers (if any) are those specified within the [ and ] of the
array type derivation. If the keyword static also appears within the [ and ] of the
array type derivation, then for each call to the function, the value of the corresponding
actual argument shall provide access to the first element of an array with at least as many
elements as specified by the size expression.
-<p><!--para 8-->
+<p><!--para 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>.
-<p><!--para 9-->
+<p><!--para 9 -->
If the list terminates with an ellipsis (, ...), no information about the number or types
of the parameters after the comma is supplied.<sup><a href="#note144"><b>144)</b></a></sup>
-<p><!--para 10-->
+<p><!--para 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.
-<p><!--para 11-->
+<p><!--para 11 -->
If, in a parameter declaration, an identifier can be treated either as a typedef name or as a
parameter name, it shall be taken as a typedef name.
-<p><!--para 12-->
+<p><!--para 12 -->
If the function declarator is not part of a definition of that function, parameters may have
incomplete type and may use the [*] notation in their sequences of declarator specifiers
to specify variable length array types.
-<p><!--para 13-->
+<p><!--para 13 -->
The storage-class specifier in the declaration specifiers for a parameter declaration, if
present, is ignored unless the declared parameter is one of the members of the parameter
type list for a function definition.
-<p><!--para 14-->
+<p><!--para 14 -->
An identifier list declares only the identifiers of the parameters of the function. An empty
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
-<!--page 151 indent 5-->
-<p><!--para 15-->
+<!--page 151 -->
+<p><!--para 15 -->
For two function types to be compatible, both shall specify compatible return types.<sup><a href="#note146"><b>146)</b></a></sup>
Moreover, the parameter type lists, if both are present, shall agree in the number of
parameters and in use of the ellipsis terminator; corresponding parameters shall have
compatibility and of a composite type, each parameter declared with function or array
type is taken as having the adjusted type and each parameter declared with qualified type
is taken as having the unqualified version of its declared type.)
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE 1 The declaration
<pre>
int f(void), *fip(), (*pfi)();</pre>
and then using indirection through the pointer result to yield an int. In the declarator (*pfi)(), the
extra parentheses are necessary to indicate that indirection through a pointer to a function yields a function
designator, which is then used to call the function; it returns an int.
-<p><!--para 17-->
+<p><!--para 17 -->
If the declaration occurs outside of any function, the identifiers have file scope and external linkage. If the
declaration occurs inside a function, the identifiers of the functions f and fip have block scope and either
internal or external linkage (depending on what file scope declarations for these identifiers are visible), and
the identifier of the pointer pfi has block scope and no linkage.
-<p><!--para 18-->
+<p><!--para 18 -->
EXAMPLE 2 The declaration
<pre>
int (*apfi[3])(int *x, int *y);</pre>
parameters that are pointers to int. The identifiers x and y are declared for descriptive purposes only and
go out of scope at the end of the declaration of apfi.
-<p><!--para 19-->
+<p><!--para 19 -->
EXAMPLE 3 The declaration
<pre>
int (*fpfi(int (*)(long), int))(int, ...);</pre>
The pointer returned by fpfi points to a function that has one int parameter and accepts zero or more
-<!--page 152 indent 5-->
+<!--page 152 -->
additional arguments of any type.
-<p><!--para 20-->
+<p><!--para 20 -->
EXAMPLE 4 The following prototype has a variably modified parameter.
<pre>
void addscalar(int n, int m,
a[i][j] += x;
}</pre>
-<p><!--para 21-->
+<p><!--para 21 -->
EXAMPLE 5 The following are all compatible function prototype declarators.
<pre>
double maximum(int n, int m, double a[n][m]);
non-null pointer to the first of at least three arrays of 5 doubles, which the others do not.)
<p><b> Forward references</b>: function definitions (<a href="#6.9.1">6.9.1</a>), type names (<a href="#6.7.7">6.7.7</a>).
-<!--page 153 indent 4-->
+<!--page 153 -->
<h6>footnotes</h6>
<p><small><a name="note144" href="#note144">144)</a> The macros defined in the <a href="#7.16"><stdarg.h></a> header (<a href="#7.16">7.16</a>) may be used to access arguments that
<a name="6.7.7" href="#6.7.7"><h4>6.7.7 Type names</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
type-name:
specifier-qualifier-list abstract-declaratoropt
direct-abstract-declaratoropt [ * ]
direct-abstract-declaratoropt ( parameter-type-listopt )</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
In several contexts, it is necessary to specify a type. This is accomplished using a type
name, which is syntactically a declaration for a function or an object of that type that
omits the identifier.<sup><a href="#note147"><b>147)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE The constructions
<pre>
(a) int
-<!--page 154 indent 4-->
+<!--page 154 -->
<h6>footnotes</h6>
<p><small><a name="note147" href="#note147">147)</a> As indicated by the syntax, empty parentheses in a type name are interpreted as ''function with no
<a name="6.7.8" href="#6.7.8"><h4>6.7.8 Type definitions</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
typedef-name:
identifier</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If a typedef name specifies a variably modified type then it shall have block scope.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
In a declaration whose storage-class specifier is typedef, each declarator defines an
identifier to be a typedef name that denotes the type specified for the identifier in the way
described in <a href="#6.7.6">6.7.6</a>. Any array size expressions associated with variable length array
type-list T '' where the derived-declarator-type-list is specified by the declarators of D. A
typedef name shares the same name space as other identifiers declared in ordinary
declarators.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE 1 After
<pre>
typedef int MILES, KLICKSP();
parameter specification returning int'', and that of x and z is the specified structure; zp is a pointer to
such a structure. The object distance has a type compatible with any other int object.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 2 After the declarations
<pre>
typedef struct s1 { int x; } t1, *tp1;
typedef struct s2 { int x; } t2, *tp2;</pre>
type t1 and the type pointed to by tp1 are compatible. Type t1 is also compatible with type struct
s1, but not compatible with the types struct s2, t2, the type pointed to by tp2, or int.
-<!--page 155 indent 4-->
-<p><!--para 6-->
+<!--page 155 -->
+<p><!--para 6 -->
EXAMPLE 3 The following obscure constructions
<pre>
typedef signed int t;
with type pointer to function returning signed int with one unnamed parameter with type signed
int'', and an identifier t with type long int.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 4 On the other hand, typedef names can be used to improve code readability. All three of the
following declarations of the signal function specify exactly the same type, the first without making use
of any typedef names.
fv *signal(int, fv *);
pfv signal(int, pfv);</pre>
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 5 If a typedef name denotes a variable length array type, the length of the array is fixed at the
time the typedef name is defined, not each time it is used:
-<!--page 156 indent 4-->
+<!--page 156 -->
<pre>
void copyt(int n)
{
<a name="6.7.9" href="#6.7.9"><h4>6.7.9 Initialization</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
initializer:
assignment-expression
[ constant-expression ]
. identifier</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
No initializer shall attempt to provide a value for an object not contained within the entity
being initialized.
-<p><!--para 3-->
+<p><!--para 3 -->
The type of the entity to be initialized shall be an array of unknown size or a complete
object type that is not a variable length array type.
-<p><!--para 4-->
+<p><!--para 4 -->
All the expressions in an initializer for an object that has static or thread storage duration
shall be constant expressions or string literals.
-<p><!--para 5-->
+<p><!--para 5 -->
If the declaration of an identifier has block scope, and the identifier has external or
internal linkage, the declaration shall have no initializer for the identifier.
-<p><!--para 6-->
+<p><!--para 6 -->
If a designator has the form
<pre>
[ constant-expression ]</pre>
then the current object (defined below) shall have array type and the expression shall be
an integer constant expression. If the array is of unknown size, any nonnegative value is
valid.
-<p><!--para 7-->
+<p><!--para 7 -->
If a designator has the form
<pre>
. identifier</pre>
then the current object (defined below) shall have structure or union type and the
identifier shall be the name of a member of that type.
-<!--page 157 indent 5-->
+<!--page 157 -->
<h6>Semantics</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
An initializer specifies the initial value stored in an object.
-<p><!--para 9-->
+<p><!--para 9 -->
Except where explicitly stated otherwise, for the purposes of this subclause unnamed
members of objects of structure and union type do not participate in initialization.
Unnamed members of structure objects have indeterminate value even after initialization.
-<p><!--para 10-->
+<p><!--para 10 -->
If an object that has automatic storage duration is not initialized explicitly, its value is
indeterminate. If an object that has static or thread storage duration is not initialized
explicitly, then:
<li> if it is a union, the first named member is initialized (recursively) according to these
rules, and any padding is initialized to zero bits;
</ul>
-<p><!--para 11-->
+<p><!--para 11 -->
The initializer for a scalar shall be a single expression, optionally enclosed in braces. The
initial value of the object is that of the expression (after conversion); the same type
constraints and conversions as for simple assignment apply, taking the type of the scalar
to be the unqualified version of its declared type.
-<p><!--para 12-->
+<p><!--para 12 -->
The rest of this subclause deals with initializers for objects that have aggregate or union
type.
-<p><!--para 13-->
+<p><!--para 13 -->
The initializer for a structure or union object that has automatic storage duration shall be
either an initializer list as described below, or a single expression that has compatible
structure or union type. In the latter case, the initial value of the object, including
unnamed members, is that of the expression.
-<p><!--para 14-->
+<p><!--para 14 -->
An array of character type may be initialized by a character string literal or UTF-8 string
literal, optionally enclosed in braces. Successive bytes of the string literal (including the
terminating null character if there is room or if the array is of unknown size) initialize the
elements of the array.
-<p><!--para 15-->
+<p><!--para 15 -->
An array with element type compatible with a qualified or unqualified version of
wchar_t may be initialized by a wide string literal, optionally enclosed in braces.
Successive wide characters of the wide string literal (including the terminating null wide
character if there is room or if the array is of unknown size) initialize the elements of the
array.
-<p><!--para 16-->
+<p><!--para 16 -->
Otherwise, the initializer for an object that has aggregate or union type shall be a brace-
enclosed list of initializers for the elements or named members.
-<!--page 158 indent 5-->
-<p><!--para 17-->
+<!--page 158 -->
+<p><!--para 17 -->
Each brace-enclosed initializer list has an associated current object. When no
designations are present, subobjects of the current object are initialized in order according
to the type of the current object: array elements in increasing subscript order, structure
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.<sup><a href="#note149"><b>149)</b></a></sup>
-<p><!--para 18-->
+<p><!--para 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.<sup><a href="#note150"><b>150)</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.
-<p><!--para 19-->
+<p><!--para 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;<sup><a href="#note151"><b>151)</b></a></sup>
all subobjects that are not initialized explicitly shall be initialized implicitly the same as
objects that have static storage duration.
-<p><!--para 20-->
+<p><!--para 20 -->
If the aggregate or union contains elements or members that are aggregates or unions,
these rules apply recursively to the subaggregates or contained unions. If the initializer of
a subaggregate or contained union begins with a left brace, the initializers enclosed by
taken to account for the elements or members of the subaggregate or the first member of
the contained union; any remaining initializers are left to initialize the next element or
member of the aggregate of which the current subaggregate or contained union is a part.
-<p><!--para 21-->
+<p><!--para 21 -->
If there are fewer initializers in a brace-enclosed list than there are elements or members
of an aggregate, or fewer characters in a string literal used to initialize an array of known
size than there are elements in the array, the remainder of the aggregate shall be
-<!--page 159 indent 5-->
-<p><!--para 22-->
+<!--page 159 -->
+<p><!--para 22 -->
If an array of unknown size is initialized, its size is determined by the largest indexed
element with an explicit initializer. The array type is completed at the end of its
initializer list.
-<p><!--para 23-->
+<p><!--para 23 -->
The evaluations of the initialization list expressions are indeterminately sequenced with
respect to one another and thus the order in which any side effects occur is
unspecified.<sup><a href="#note152"><b>152)</b></a></sup>
-<p><!--para 24-->
+<p><!--para 24 -->
EXAMPLE 1 Provided that <a href="#7.3"><complex.h></a> has been #included, the declarations
<pre>
int i = <a href="#3.5">3.5</a>;
double complex c = 5 + 3 * I;</pre>
define and initialize i with the value 3 and c with the value 5.0 + i3.0.
-<p><!--para 25-->
+<p><!--para 25 -->
EXAMPLE 2 The declaration
<pre>
int x[] = { 1, 3, 5 };</pre>
defines and initializes x as a one-dimensional array object that has three elements, as no size was specified
and there are three initializers.
-<p><!--para 26-->
+<p><!--para 26 -->
EXAMPLE 3 The declaration
<pre>
int y[4][3] = {
The initializer for y[0] does not begin with a left brace, so three items from the list are used. Likewise the
next three are taken successively for y[1] and y[2].
-<p><!--para 27-->
+<p><!--para 27 -->
EXAMPLE 4 The declaration
<pre>
int z[4][3] = {
};</pre>
initializes the first column of z as specified and initializes the rest with zeros.
-<p><!--para 28-->
+<p><!--para 28 -->
EXAMPLE 5 The declaration
<pre>
struct { int a[3], b; } w[] = { { 1 }, 2 };</pre>
-<!--page 160 indent 5-->
+<!--page 160 -->
structures: w[0].a[0] is 1 and w[1].a[0] is 2; all the other elements are zero.
-<p><!--para 29-->
+<p><!--para 29 -->
EXAMPLE 6 The declaration
<pre>
short q[4][3][2] = {
}
};</pre>
in a fully bracketed form.
-<p><!--para 30-->
+<p><!--para 30 -->
Note that the fully bracketed and minimally bracketed forms of initialization are, in general, less likely to
cause confusion.
-<p><!--para 31-->
+<p><!--para 31 -->
EXAMPLE 7 One form of initialization that completes array types involves typedef names. Given the
declaration
<pre>
<pre>
int a[] = { 1, 2 }, b[] = { 3, 4, 5 };</pre>
due to the rules for incomplete types.
-<!--page 161 indent 5-->
-<p><!--para 32-->
+<!--page 161 -->
+<p><!--para 32 -->
EXAMPLE 8 The declaration
<pre>
char s[] = "abc", t[3] = "abc";</pre>
with length 4 whose elements are initialized with a character string literal. If an attempt is made to use p to
modify the contents of the array, the behavior is undefined.
-<p><!--para 33-->
+<p><!--para 33 -->
EXAMPLE 9 Arrays can be initialized to correspond to the elements of an enumeration by using
designators:
<pre>
[member_one] = "member one",
};</pre>
-<p><!--para 34-->
+<p><!--para 34 -->
EXAMPLE 10 Structure members can be initialized to nonzero values without depending on their order:
<pre>
div_t answer = { .quot = 2, .rem = -1 };</pre>
-<p><!--para 35-->
+<p><!--para 35 -->
EXAMPLE 11 Designators can be used to provide explicit initialization when unadorned initializer lists
might be misunderstood:
<pre>
struct { int a[3], b; } w[] =
{ [0].a = {1}, [1].a[0] = 2 };</pre>
-<p><!--para 36-->
+<p><!--para 36 -->
EXAMPLE 12 Space can be ''allocated'' from both ends of an array by using a single designator:
-<p><!--para 37-->
+<p><!--para 37 -->
<pre>
int a[MAX] = {
1, 3, 5, 7, 9, [MAX-5] = 8, 6, 4, 2, 0
In the above, if MAX is greater than ten, there will be some zero-valued elements in the middle; if it is less
than ten, some of the values provided by the first five initializers will be overridden by the second five.
-<p><!--para 38-->
+<p><!--para 38 -->
EXAMPLE 13 Any member of a union can be initialized:
<pre>
union { /* ... */ } u = { .any_member = 42 };</pre>
<p><b> Forward references</b>: common definitions <a href="#7.19"><stddef.h></a> (<a href="#7.19">7.19</a>).
-<!--page 162 indent 4-->
+<!--page 162 -->
<h6>footnotes</h6>
<p><small><a name="note148" href="#note148">148)</a> If the initializer list for a subaggregate or contained union does not begin with a left brace, its
<a name="6.7.10" href="#6.7.10"><h4>6.7.10 Static assertions</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
static_assert-declaration:
_Static_assert ( constant-expression , string-literal ) ;</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The constant expression shall compare unequal to 0.
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The constant expression shall be an integer constant expression. If the value of the
constant expression compares unequal to 0, the declaration has no effect. Otherwise, the
constraint is violated and the implementation shall produce a diagnostic message that
includes the text of the string literal, except that characters not in the basic source
character set are not required to appear in the message.
<p><b> Forward references</b>: diagnostics (<a href="#7.2">7.2</a>).
-<!--page 163 indent 4-->
+<!--page 163 -->
<a name="6.8" href="#6.8"><h3>6.8 Statements and blocks</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
statement:
labeled-statement
iteration-statement
jump-statement</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A statement specifies an action to be performed. Except as indicated, statements are
executed in sequence.
-<p><!--para 3-->
+<p><!--para 3 -->
A block allows a set of declarations and statements to be grouped into one syntactic unit.
The initializers of objects that have automatic storage duration, and the variable length
array declarators of ordinary identifiers with block scope, are evaluated and the values are
stored in the objects (including storing an indeterminate value in objects without an
initializer) each time the declaration is reached in the order of execution, as if it were a
statement, and within each declaration in the order that declarators appear.
-<p><!--para 4-->
+<p><!--para 4 -->
A full expression is an expression that is not part of another expression or of a declarator.
Each of the following is a full expression: an initializer that is not part of a compound
literal; the expression in an expression statement; the controlling expression of a selection
<a name="6.8.1" href="#6.8.1"><h4>6.8.1 Labeled statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
labeled-statement:
identifier : statement
case constant-expression : statement
default : statement</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A case or default label shall appear only in a switch statement. Further
constraints on such labels are discussed under the switch statement.
-<!--page 164 indent 4-->
-<p><!--para 3-->
+<!--page 164 -->
+<p><!--para 3 -->
Label names shall be unique within a function.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
Any statement may be preceded by a prefix that declares an identifier as a label name.
Labels in themselves do not alter the flow of control, which continues unimpeded across
them.
<a name="6.8.2" href="#6.8.2"><h4>6.8.2 Compound statement</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
compound-statement:
{ block-item-listopt }
declaration
statement</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A compound statement is a block.
<a name="6.8.3" href="#6.8.3"><h4>6.8.3 Expression and null statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
expression-statement:
expressionopt ;</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The expression in an expression statement is evaluated as a void expression for its side
effects.<sup><a href="#note153"><b>153)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
A null statement (consisting of just a semicolon) performs no operations.
-<p><!--para 4-->
+<p><!--para 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
a cast:
-<!--page 165 indent 4-->
-<p><!--para 5-->
+<!--page 165 -->
+<p><!--para 5 -->
EXAMPLE 2 In the program fragment
<pre>
char *s;
;</pre>
a null statement is used to supply an empty loop body to the iteration statement.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 3 A null statement may also be used to carry a label just before the closing } of a compound
statement.
<pre>
<a name="6.8.4" href="#6.8.4"><h4>6.8.4 Selection statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
selection-statement:
if ( expression ) statement
if ( expression ) statement else statement
switch ( expression ) statement</pre>
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A selection statement selects among a set of statements depending on the value of a
controlling expression.
-<p><!--para 3-->
+<p><!--para 3 -->
A selection statement is a block whose scope is a strict subset of the scope of its
enclosing block. Each associated substatement is also a block whose scope is a strict
subset of the scope of the selection statement.
<a name="6.8.4.1" href="#6.8.4.1"><h5>6.8.4.1 The if statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The controlling expression of an if statement shall have scalar type.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
In both forms, the first substatement is executed if the expression compares unequal to 0.
In the else form, the second substatement is executed if the expression compares equal
-<!--page 166 indent 4-->
+<!--page 166 -->
to 0. If the first substatement is reached via a label, the second substatement is not
executed.
-<p><!--para 3-->
+<p><!--para 3 -->
An else is associated with the lexically nearest preceding if that is allowed by the
syntax.
<a name="6.8.4.2" href="#6.8.4.2"><h5>6.8.4.2 The switch statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The controlling expression of a switch statement shall have integer type.
-<p><!--para 2-->
+<p><!--para 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.<sup><a href="#note154"><b>154)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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.
expressions with values that duplicate case constant expressions in the enclosing
switch statement.)
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
A switch statement causes control to jump to, into, or past the statement that is the
switch body, depending on the value of a controlling expression, and on the presence of a
default label and the values of any case labels on or in the switch body. A case or
default label is accessible only within the closest enclosing switch statement.
-<p><!--para 5-->
+<p><!--para 5 -->
The integer promotions are performed on the controlling expression. The constant
expression in each case label is converted to the promoted type of the controlling
expression. If a converted value matches that of the promoted controlling expression,
expression matches and there is no default label, no part of the switch body is
executed.
Implementation limits
-<p><!--para 6-->
+<p><!--para 6 -->
As discussed in <a href="#5.2.4.1">5.2.4.1</a>, the implementation may limit the number of case values in a
switch statement.
-<!--page 167 indent 4-->
-<p><!--para 7-->
+<!--page 167 -->
+<p><!--para 7 -->
EXAMPLE In the artificial program fragment
<pre>
switch (expr)
<a name="6.8.5" href="#6.8.5"><h4>6.8.5 Iteration statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
iteration-statement:
while ( expression ) statement
for ( expressionopt ; expressionopt ; expressionopt ) statement
for ( declaration expressionopt ; expressionopt ) statement</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The controlling expression of an iteration statement shall have scalar type.
-<p><!--para 3-->
+<p><!--para 3 -->
The declaration part of a for statement shall only declare identifiers for objects having
storage class auto or register.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
An iteration statement causes a statement called the loop body to be executed repeatedly
until the controlling expression compares equal to 0. The repetition occurs regardless of
whether the loop body is entered from the iteration statement or by a jump.<sup><a href="#note155"><b>155)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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.
-<p><!--para 6-->
+<p><!--para 6 -->
An iteration statement whose controlling expression is not a constant expression,<sup><a href="#note156"><b>156)</b></a></sup> that
performs no input/output operations, does not access volatile objects, and performs no
synchronization or atomic operations in its body, controlling expression, or (in the case of
-<!--page 168 indent 4-->
+<!--page 168 -->
a for statement) its expression-3, may be assumed by the implementation to
terminate.<sup><a href="#note157"><b>157)</b></a></sup>
</small>
<a name="6.8.5.1" href="#6.8.5.1"><h5>6.8.5.1 The while statement</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The evaluation of the controlling expression takes place before each execution of the loop
body.
<a name="6.8.5.2" href="#6.8.5.2"><h5>6.8.5.2 The do statement</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The evaluation of the controlling expression takes place after each execution of the loop
body.
<a name="6.8.5.3" href="#6.8.5.3"><h5>6.8.5.3 The for statement</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The statement
<pre>
for ( clause-1 ; expression-2 ; expression-3 ) statement</pre>
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.<sup><a href="#note158"><b>158)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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"><h4>6.8.6 Jump statements</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
jump-statement:
goto identifier ;
-<!--page 169 indent 4-->
+<!--page 169 -->
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A jump statement causes an unconditional jump to another place.
<a name="6.8.6.1" href="#6.8.6.1"><h5>6.8.6.1 The goto statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The identifier in a goto statement shall name a label located somewhere in the enclosing
function. A goto statement shall not jump from outside the scope of an identifier having
a variably modified type to inside the scope of that identifier.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A goto statement causes an unconditional jump to the statement prefixed by the named
label in the enclosing function.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE 1 It is sometimes convenient to jump into the middle of a complicated set of statements. The
following outline presents one possible approach to a problem based on these three assumptions:
<ol>
<li> The general initialization code is too large to warrant duplication.
<li> The code to determine the next operation is at the head of the loop. (To allow it to be reached by
continue statements, for example.)
-<!--page 170 indent 4-->
+<!--page 170 -->
</ol>
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
/* ... */
goto first_time;
<a name="6.8.6.2" href="#6.8.6.2"><h5>6.8.6.2 The continue statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A continue statement shall appear only in or as a loop body.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A continue statement causes a jump to the loop-continuation portion of the smallest
enclosing iteration statement; that is, to the end of the loop body. More precisely, in each
of the statements
<a name="6.8.6.3" href="#6.8.6.3"><h5>6.8.6.3 The break statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A break statement shall appear only in or as a switch body or loop body.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A break statement terminates execution of the smallest enclosing switch or iteration
statement.
-<!--page 171 indent 4-->
+<!--page 171 -->
<a name="6.8.6.4" href="#6.8.6.4"><h5>6.8.6.4 The return statement</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A return statement with an expression shall not appear in a function whose return type
is void. A return statement without an expression shall only appear in a function
whose return type is void.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A return statement terminates execution of the current function and returns control to
its caller. A function may have any number of return statements.
-<p><!--para 3-->
+<p><!--para 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.<sup><a href="#note160"><b>160)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE In:
<pre>
struct s { double i; } f(void);
-<!--page 172 indent 4-->
+<!--page 172 -->
<h6>footnotes</h6>
<p><small><a name="note160" href="#note160">160)</a> The return statement is not an assignment. The overlap restriction of subclause <a href="#6.5.16.1">6.5.16.1</a> does not
<a name="6.9" href="#6.9"><h3>6.9 External definitions</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
translation-unit:
external-declaration
function-definition
declaration</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The storage-class specifiers auto and register shall not appear in the declaration
specifiers in an external declaration.
-<p><!--para 3-->
+<p><!--para 3 -->
There shall be no more than one external definition for each identifier declared with
internal linkage in a translation unit. Moreover, if an identifier declared with internal
linkage is used in an expression (other than as a part of the operand of a sizeof
operator whose result is an integer constant), there shall be exactly one external definition
for the identifier in the translation unit.
<h6>Semantics</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
As discussed in <a href="#5.1.1.1">5.1.1.1</a>, the unit of program text after preprocessing is a translation unit,
which consists of a sequence of external declarations. These are described as ''external''
because they appear outside any function (and hence have file scope). As discussed in
<a href="#6.7">6.7</a>, a declaration that also causes storage to be reserved for an object or a function named
by the identifier is a definition.
-<p><!--para 5-->
+<p><!--para 5 -->
An external definition is an external declaration that is also a definition of a function
(other than an inline definition) or an object. If an identifier declared with external
linkage is used in an expression (other than as part of the operand of a sizeof operator
-<!--page 173 indent 4-->
+<!--page 173 -->
<h6>footnotes</h6>
<p><small><a name="note161" href="#note161">161)</a> Thus, if an identifier declared with external linkage is not used in an expression, there need be no
<a name="6.9.1" href="#6.9.1"><h4>6.9.1 Function definitions</h4></a>
<h6>Syntax</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
function-definition:
declaration-specifiers declarator declaration-listopt compound-statement
declaration
declaration-list declaration</pre>
<h6>Constraints</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The identifier declared in a function definition (which is the name of the function) shall
have a function type, as specified by the declarator portion of the function definition.<sup><a href="#note162"><b>162)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The return type of a function shall be void or a complete object type other than array
type.
-<p><!--para 4-->
+<p><!--para 4 -->
The storage-class specifier, if any, in the declaration specifiers shall be either extern or
static.
-<p><!--para 5-->
+<p><!--para 5 -->
If the declarator includes a parameter type list, the declaration of each parameter shall
include an identifier, except for the special case of a parameter list consisting of a single
parameter of type void, in which case there shall not be an identifier. No declaration list
shall follow.
-<p><!--para 6-->
+<p><!--para 6 -->
If the declarator includes an identifier list, each declaration in the declaration list shall
have at least one declarator, those declarators shall declare only identifiers from the
identifier list, and every identifier in the identifier list shall be declared. An identifier
-<!--page 174 indent 5-->
+<!--page 174 -->
<h6>Semantics</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The declarator in a function definition specifies the name of the function being defined
and the identifiers of its parameters. If the declarator includes a parameter type list, the
list also specifies the types of all the parameters; such a declarator also serves as a
following declaration list. In either case, the type of each parameter is adjusted as
described in <a href="#6.7.6.3">6.7.6.3</a> for a parameter type list; the resulting type shall be a complete object
type.
-<p><!--para 8-->
+<p><!--para 8 -->
If a function that accepts a variable number of arguments is defined without a parameter
type list that ends with the ellipsis notation, the behavior is undefined.
-<p><!--para 9-->
+<p><!--para 9 -->
Each parameter has automatic storage duration; its identifier is an lvalue.<sup><a href="#note164"><b>164)</b></a></sup> The layout
of the storage for parameters is unspecified.
-<p><!--para 10-->
+<p><!--para 10 -->
On entry to the function, the size expressions of each variably modified parameter are
evaluated and the value of each argument expression is converted to the type of the
corresponding parameter as if by assignment. (Array expressions and function
designators as arguments were converted to pointers before the call.)
-<p><!--para 11-->
+<p><!--para 11 -->
After all parameters have been assigned, the compound statement that constitutes the
body of the function definition is executed.
-<p><!--para 12-->
+<p><!--para 12 -->
If the } that terminates a function is reached, and the value of the function call is used by
the caller, the behavior is undefined.
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 1 In the following:
<pre>
extern int max(int a, int b)
-<!--page 175 indent 5-->
+<!--page 175 -->
<pre>
extern int max(a, b)
int a, b;
that the first form acts as a prototype declaration that forces conversion of the arguments of subsequent calls
to the function, whereas the second form does not.
-<p><!--para 14-->
+<p><!--para 14 -->
EXAMPLE 2 To pass one function to another, one might say
<pre>
int f(void);
<a name="6.9.2" href="#6.9.2"><h4>6.9.2 External object definitions</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
If the declaration of an identifier for an object has file scope and an initializer, the
declaration is an external definition for the identifier.
-<p><!--para 2-->
+<p><!--para 2 -->
A declaration of an identifier for an object that has file scope without an initializer, and
without a storage-class specifier or with the storage-class specifier static, constitutes a
tentative definition. If a translation unit contains one or more tentative definitions for an
the behavior is exactly as if the translation unit contains a file scope declaration of that
identifier, with the composite type as of the end of the translation unit, with an initializer
equal to 0.
-<p><!--para 3-->
+<p><!--para 3 -->
If the declaration of an identifier for an object is a tentative definition and has internal
linkage, the declared type shall not be an incomplete type.
-<!--page 176 indent 4-->
-<p><!--para 4-->
+<!--page 176 -->
+<p><!--para 4 -->
EXAMPLE 1
<pre>
int i1 = 1; // definition, external linkage
extern int i4; // refers to previous, whose linkage is external
extern int i5; // refers to previous, whose linkage is internal</pre>
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE 2 If at the end of the translation unit containing
<pre>
int i[];</pre>
the array i still has incomplete type, the implicit initializer causes it to have one element, which is set to
zero on program startup.
-<!--page 177 indent 4-->
+<!--page 177 -->
<a name="6.10" href="#6.10"><h3>6.10 Preprocessing directives</h3></a>
<h6>Syntax</h6>
-<p><!--para 1-->
-<!--page 178 indent 4-->
+<p><!--para 1 -->
+<!--page 178 -->
<pre>
preprocessing-file:
groupopt
new-line:
the new-line character</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the
following constraints: The first token in the sequence is a # preprocessing token that (at
the start of translation phase 4) is either the first character in the source file (optionally
line character that follows the first token in the sequence.<sup><a href="#note165"><b>165)</b></a></sup> A new-line character ends
the preprocessing directive even if it occurs within what would otherwise be an
-<!--page 179 indent 4-->
+<!--page 179 -->
invocation of a function-like macro.
-<p><!--para 3-->
+<p><!--para 3 -->
A text line shall not begin with a # preprocessing token. A non-directive shall not begin
with any of the directive names appearing in the syntax.
-<p><!--para 4-->
+<p><!--para 4 -->
When in a group that is skipped (<a href="#6.10.1">6.10.1</a>), the directive syntax is relaxed to allow any
sequence of preprocessing tokens to occur between the directive name and the following
new-line character.
<h6>Constraints</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The only white-space characters that shall appear between preprocessing tokens within a
preprocessing directive (from just after the introducing # preprocessing token through
just before the terminating new-line character) are space and horizontal-tab (including
spaces that have replaced comments or possibly other white-space characters in
translation phase 3).
<h6>Semantics</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The implementation can process and skip sections of source files conditionally, include
other source files, and replace macros. These capabilities are called preprocessing,
because conceptually they occur before translation of the resulting translation unit.
-<p><!--para 7-->
+<p><!--para 7 -->
The preprocessing tokens within a preprocessing directive are not subject to macro
expansion unless otherwise stated.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE In:
<pre>
#define EMPTY
<a name="6.10.1" href="#6.10.1"><h4>6.10.1 Conditional inclusion</h4></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The expression that controls conditional inclusion shall be an integer constant expression
except that: identifiers (including those lexically identical to keywords) are interpreted as *
described below;<sup><a href="#note166"><b>166)</b></a></sup> and it may contain unary operator expressions of the form
which evaluate to 1 if the identifier is currently defined as a macro name (that is, if it is
-<!--page 180 indent 4-->
+<!--page 180 -->
predefined or if it has been the subject of a #define preprocessing directive without an
intervening #undef directive with the same subject identifier), 0 if it is not.
-<p><!--para 2-->
+<p><!--para 2 -->
Each preprocessing token that remains (in the list of preprocessing tokens that will
become the controlling expression) after all macro replacements have occurred shall be in
the lexical form of a token (<a href="#6.4">6.4</a>).
<h6>Semantics</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Preprocessing directives of the forms
<pre>
# if constant-expression new-line groupopt
# elif constant-expression new-line groupopt</pre>
check whether the controlling constant expression evaluates to nonzero.
-<p><!--para 4-->
+<p><!--para 4 -->
Prior to evaluation, macro invocations in the list of preprocessing tokens that will become
the controlling constant expression are replaced (except for those macro names modified
by the defined unary operator), just as in normal text. If the token defined is
-<!--page 181 indent 4-->
-<p><!--para 5-->
+<!--page 181 -->
+<p><!--para 5 -->
Preprocessing directives of the forms
<pre>
# ifdef identifier new-line groupopt
check whether the identifier is or is not currently defined as a macro name. Their
conditions are equivalent to #if defined identifier and #if !defined identifier
respectively.
-<p><!--para 6-->
+<p><!--para 6 -->
Each directive's condition is checked in order. If it evaluates to false (zero), the group
that it controls is skipped: directives are processed only through the name that determines
the directive in order to keep track of the level of nested conditionals; the rest of the
<a name="6.10.2" href="#6.10.2"><h4>6.10.2 Source file inclusion</h4></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A #include directive shall identify a header or source file that can be processed by the
implementation.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A preprocessing directive of the form
<pre>
# include <h-char-sequence> new-line</pre>
the specified sequence between the < and > delimiters, and causes the replacement of that
directive by the entire contents of the header. How the places are specified or the header
identified is implementation-defined.
-<p><!--para 3-->
+<p><!--para 3 -->
A preprocessing directive of the form
<pre>
# include "q-char-sequence" new-line</pre>
by the specified sequence between the " delimiters. The named source file is searched
-<!--page 182 indent 4-->
+<!--page 182 -->
for in an implementation-defined manner. If this search is not supported, or if the search
fails, the directive is reprocessed as if it read
<pre>
# include <h-char-sequence> new-line</pre>
with the identical contained sequence (including > characters, if any) from the original
directive.
-<p><!--para 4-->
+<p><!--para 4 -->
A preprocessing directive of the form
<pre>
# include pp-tokens new-line</pre>
the two previous forms.<sup><a href="#note170"><b>170)</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.
-<p><!--para 5-->
+<p><!--para 5 -->
The implementation shall provide unique mappings for sequences consisting of one or
more nondigits or digits (<a href="#6.4.2.1">6.4.2.1</a>) followed by a period (.) and a single nondigit. The
first character shall not be a digit. The implementation may ignore distinctions of
alphabetical case and restrict the mapping to eight significant characters before the
period.
-<p><!--para 6-->
+<p><!--para 6 -->
A #include preprocessing directive may appear in a source file that has been read
because of a #include directive in another file, up to an implementation-defined
nesting limit (see <a href="#5.2.4.1">5.2.4.1</a>).
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1 The most common uses of #include preprocessing directives are as in the following:
<pre>
#include <a href="#7.21"><stdio.h></a>
-<!--page 183 indent 4-->
-<p><!--para 8-->
+<!--page 183 -->
+<p><!--para 8 -->
EXAMPLE 2 This illustrates macro-replaced #include directives:
<pre>
#if VERSION == 1
<a name="6.10.3" href="#6.10.3"><h4>6.10.3 Macro replacement</h4></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
Two replacement lists are identical if and only if the preprocessing tokens in both have
the same number, ordering, spelling, and white-space separation, where all white-space
separations are considered identical.
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier currently defined as an object-like macro shall not be redefined by another
#define preprocessing directive unless the second definition is an object-like macro
definition and the two replacement lists are identical. Likewise, an identifier currently
preprocessing directive unless the second definition is a function-like macro definition
that has the same number and spelling of parameters, and the two replacement lists are
identical.
-<p><!--para 3-->
+<p><!--para 3 -->
There shall be white-space between the identifier and the replacement list in the definition
of an object-like macro.
-<p><!--para 4-->
+<p><!--para 4 -->
If the identifier-list in the macro definition does not end with an ellipsis, the number of
arguments (including those arguments consisting of no preprocessing tokens) in an
invocation of a function-like macro shall equal the number of parameters in the macro
definition. Otherwise, there shall be more arguments in the invocation than there are
parameters in the macro definition (excluding the ...). There shall exist a )
preprocessing token that terminates the invocation.
-<p><!--para 5-->
+<p><!--para 5 -->
The identifier __VA_ARGS__ shall occur only in the replacement-list of a function-like
macro that uses the ellipsis notation in the parameters.
-<p><!--para 6-->
+<p><!--para 6 -->
A parameter identifier in a function-like macro shall be uniquely declared within its
scope.
<h6>Semantics</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The identifier immediately following the define is called the macro name. There is one
name space for macro names. Any white-space characters preceding or following the
replacement list of preprocessing tokens are not considered part of the replacement list
-<!--page 184 indent 5-->
+<!--page 184 -->
for either form of macro.
-<p><!--para 8-->
+<p><!--para 8 -->
If a # preprocessing token, followed by an identifier, occurs lexically at the point at which
a preprocessing directive could begin, the identifier is not subject to macro replacement.
-<p><!--para 9-->
+<p><!--para 9 -->
A preprocessing directive of the form
<pre>
# define identifier replacement-list new-line</pre>
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.
-<p><!--para 10-->
+<p><!--para 10 -->
A preprocessing directive of the form
<pre>
# define identifier lparen identifier-listopt ) replacement-list new-line
left and right parenthesis preprocessing tokens. Within the sequence of preprocessing
tokens making up an invocation of a function-like macro, new-line is considered a normal
white-space character.
-<p><!--para 11-->
+<p><!--para 11 -->
The sequence of preprocessing tokens bounded by the outside-most matching parentheses
forms the list of arguments for the function-like macro. The individual arguments within
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,<sup><a href="#note172"><b>172)</b></a></sup> the behavior is undefined.
-<p><!--para 12-->
+<p><!--para 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:
-<!--page 185 indent 4-->
+<!--page 185 -->
the variable arguments. The number of arguments so combined is such that, following
merger, the number of arguments is one more than the number of parameters in the macro
definition (excluding the ...).
</small>
<a name="6.10.3.1" href="#6.10.3.1"><h5>6.10.3.1 Argument substitution</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
After the arguments for the invocation of a function-like macro have been identified,
argument substitution takes place. A parameter in the replacement list, unless preceded
by a # or ## preprocessing token or followed by a ## preprocessing token (see below), is
expanded. Before being substituted, each argument's preprocessing tokens are
completely macro replaced as if they formed the rest of the preprocessing file; no other
preprocessing tokens are available.
-<p><!--para 2-->
+<p><!--para 2 -->
An identifier __VA_ARGS__ that occurs in the replacement list shall be treated as if it
were a parameter, and the variable arguments shall form the preprocessing tokens used to
replace it.
<a name="6.10.3.2" href="#6.10.3.2"><h5>6.10.3.2 The # operator</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
Each # preprocessing token in the replacement list for a function-like macro shall be
followed by a parameter as the next preprocessing token in the replacement list.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If, in the replacement list, a parameter is immediately preceded by a # preprocessing
token, both are replaced by a single character string literal preprocessing token that
contains the spelling of the preprocessing token sequence for the corresponding
results is not a valid character string literal, the behavior is undefined. The character
string literal corresponding to an empty argument is "". The order of evaluation of # and
## operators is unspecified.
-<!--page 186 indent 4-->
+<!--page 186 -->
<a name="6.10.3.3" href="#6.10.3.3"><h5>6.10.3.3 The ## operator</h5></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A ## preprocessing token shall not occur at the beginning or at the end of a replacement
list for either form of macro definition.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If, in the replacement list of a function-like macro, a parameter is immediately preceded
or followed by a ## preprocessing token, the parameter is replaced by the corresponding
argument's preprocessing token sequence; however, if an argument consists of no
preprocessing tokens, the parameter is replaced by a placemarker preprocessing token
instead.<sup><a href="#note173"><b>173)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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
If the result is not a valid preprocessing token, the behavior is undefined. The resulting
token is available for further macro replacement. The order of evaluation of ## operators
is unspecified.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE In the following fragment:
<pre>
#define hash_hash # ## #
this new token is not the ## operator.
-<!--page 187 indent 4-->
+<!--page 187 -->
<h6>footnotes</h6>
<p><small><a name="note173" href="#note173">173)</a> Placemarker preprocessing tokens do not appear in the syntax because they are temporary entities that
</small>
<a name="6.10.3.4" href="#6.10.3.4"><h5>6.10.3.4 Rescanning and further replacement</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
After all parameters in the replacement list have been substituted and # and ##
processing has taken place, all placemarker preprocessing tokens are removed. The
resulting preprocessing token sequence is then rescanned, along with all subsequent
preprocessing tokens of the source file, for more macro names to replace.
-<p><!--para 2-->
+<p><!--para 2 -->
If the name of the macro being replaced is found during this scan of the replacement list
(not including the rest of the source file's preprocessing tokens), it is not replaced.
Furthermore, if any nested replacements encounter the name of the macro being replaced,
it is not replaced. These nonreplaced macro name preprocessing tokens are no longer
available for further replacement even if they are later (re)examined in contexts in which
that macro name preprocessing token would otherwise have been replaced.
-<p><!--para 3-->
+<p><!--para 3 -->
The resulting completely macro-replaced preprocessing token sequence is not processed
as a preprocessing directive even if it resembles one, but all pragma unary operator
expressions within it are then processed as specified in <a href="#6.10.9">6.10.9</a> below.
<a name="6.10.3.5" href="#6.10.3.5"><h5>6.10.3.5 Scope of macro definitions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A macro definition lasts (independent of block structure) until a corresponding #undef
directive is encountered or (if none is encountered) until the end of the preprocessing
translation unit. Macro definitions have no significance after translation phase 4.
-<p><!--para 2-->
+<p><!--para 2 -->
A preprocessing directive of the form
<pre>
# undef identifier new-line</pre>
causes the specified identifier no longer to be defined as a macro name. It is ignored if
the specified identifier is not currently defined as a macro name.
-<p><!--para 3-->
+<p><!--para 3 -->
EXAMPLE 1 The simplest use of this facility is to define a ''manifest constant'', as in
<pre>
#define TABSIZE 100
int table[TABSIZE];</pre>
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE 2 The following defines a function-like macro whose value is the maximum of its arguments.
It has the advantages of working for any compatible types of the arguments and of generating in-line code
without the overhead of function calling. It has the disadvantages of evaluating one or the other of its
<pre>
#define max(a, b) ((a) > (b) ? (a) : (b))</pre>
The parentheses ensure that the arguments and the resulting expression are bound properly.
-<!--page 188 indent 4-->
-<p><!--para 5-->
+<!--page 188 -->
+<p><!--para 5 -->
EXAMPLE 3 To illustrate the rules for redefinition and reexamination, the sequence
<pre>
#define x 3
int i[] = { 1, 23, 4, 5, };
char c[2][6] = { "hello", "" };</pre>
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 4 To illustrate the rules for creating character string literals and concatenating tokens, the
sequence
<pre>
glue(HIGH, LOW);
xglue(HIGH, LOW)</pre>
results in
-<!--page 189 indent 4-->
+<!--page 189 -->
<pre>
printf("x" "1" "= %d, x" "2" "= %s", x1, x2);
fputs(
"hello, world"</pre>
Space around the # and ## tokens in the macro definition is optional.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 5 To illustrate the rules for placemarker preprocessing tokens, the sequence
<pre>
#define t(x,y,z) x ## y ## z
int j[] = { 123, 45, 67, 89,
10, 11, 12, };</pre>
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 6 To demonstrate the redefinition rules, the following sequence is valid.
<pre>
#define OBJ_LIKE (1-1)
#define FUNC_LIKE(b) ( a ) // different parameter usage
#define FUNC_LIKE(b) ( b ) // different parameter spelling</pre>
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 7 Finally, to show the variable argument list macro facilities:
-<!--page 190 indent 4-->
+<!--page 190 -->
<pre>
#define debug(...) fprintf(stderr, __VA_ARGS__)
#define showlist(...) puts(#__VA_ARGS__)
<a name="6.10.4" href="#6.10.4"><h4>6.10.4 Line control</h4></a>
<h6>Constraints</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
The string literal of a #line directive, if present, shall be a character string literal.
<h6>Semantics</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The line number of the current source line is one greater than the number of new-line
characters read or introduced in translation phase 1 (<a href="#5.1.1.2">5.1.1.2</a>) while processing the source
file to the current token.
-<p><!--para 3-->
+<p><!--para 3 -->
A preprocessing directive of the form
<pre>
# line digit-sequence new-line</pre>
with a source line that has a line number as specified by the digit sequence (interpreted as
a decimal integer). The digit sequence shall not specify zero, nor a number greater than
2147483647.
-<p><!--para 4-->
+<p><!--para 4 -->
A preprocessing directive of the form
<pre>
# line digit-sequence "s-char-sequenceopt" new-line</pre>
sets the presumed line number similarly and changes the presumed name of the source
file to be the contents of the character string literal.
-<p><!--para 5-->
+<p><!--para 5 -->
A preprocessing directive of the form
<pre>
# line pp-tokens new-line</pre>
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 and is then processed as appropriate.
-<!--page 191 indent 4-->
+<!--page 191 -->
<a name="6.10.5" href="#6.10.5"><h4>6.10.5 Error directive</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A preprocessing directive of the form
<pre>
# error pp-tokensopt new-line</pre>
<a name="6.10.6" href="#6.10.6"><h4>6.10.6 Pragma directive</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A preprocessing directive of the form
<pre>
# pragma pp-tokensopt new-line</pre>
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.
-<p><!--para 2-->
+<p><!--para 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 forms<sup><a href="#note175"><b>175)</b></a></sup> whose meanings are described
-<!--page 192 indent 4-->
+<!--page 192 -->
<h6>footnotes</h6>
<p><small><a name="note174" href="#note174">174)</a> An implementation is not required to perform macro replacement in pragmas, but it is permitted
<a name="6.10.7" href="#6.10.7"><h4>6.10.7 Null directive</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A preprocessing directive of the form
<pre>
# new-line</pre>
has no effect.
<a name="6.10.8" href="#6.10.8"><h4>6.10.8 Predefined macro names</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The values of the predefined macros listed in the following subclauses<sup><a href="#note176"><b>176)</b></a></sup> (except for
__FILE__ and __LINE__) remain constant throughout the translation unit.
-<p><!--para 2-->
+<p><!--para 2 -->
None of these macro names, nor the identifier defined, shall be the subject of a
#define or a #undef preprocessing directive. Any other predefined macro names
shall begin with a leading underscore followed by an uppercase letter or a second
underscore.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall not predefine the macro __cplusplus, nor shall it define it
in any standard header.
<p><b> Forward references</b>: standard headers (<a href="#7.1.2">7.1.2</a>).
</small>
<a name="6.10.8.1" href="#6.10.8.1"><h5>6.10.8.1 Mandatory macros</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following macro names shall be defined by the implementation:
__DATE__ The date of translation of the preprocessing translation unit: a character
<pre>
-<!--page 193 indent 4-->
+<!--page 193 -->
__STDC_VERSION__ The integer constant 201ymmL.<sup><a href="#note178"><b>178)</b></a></sup>
__TIME__ The time of translation of the preprocessing translation unit: a character
<pre>
</small>
<a name="6.10.8.2" href="#6.10.8.2"><h5>6.10.8.2 Environment macros</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following macro names are conditionally defined by the implementation:
__STDC_ISO_10646__ An integer constant of the form yyyymmL (for example,
<pre>
-<!--page 194 indent 4-->
+<!--page 194 -->
<a name="6.10.8.3" href="#6.10.8.3"><h5>6.10.8.3 Conditional feature macros</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following macro names are conditionally defined by the implementation:
__STDC_ANALYZABLE__ The integer constant 1, intended to indicate conformance to
<pre>
type qualifier and the <a href="#7.17"><stdatomic.h></a> header) or the <a href="#7.25"><threads.h></a>
header.</pre>
__STDC_NO_VLA__ The integer constant 1, intended to indicate that the
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
implementation does not support variable length arrays or variably
modified types.</pre>
<a name="6.10.9" href="#6.10.9"><h4>6.10.9 Pragma operator</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
A unary operator expression of the form:
<pre>
_Pragma ( string-literal )</pre>
preprocessing tokens that are executed as if they were the pp-tokens in a pragma
-<!--page 195 indent 4-->
+<!--page 195 -->
directive. The original four preprocessing tokens in the unary operator expression are
removed.
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE A directive of the form:
<pre>
#pragma listing on "..\listing.dir"</pre>
_Pragma ( "listing on \"..\\listing.dir\"" )</pre>
The latter form is processed in the same way whether it appears literally as shown, or results from macro
replacement, as in:
-<!--page 196 indent 4-->
+<!--page 196 -->
<pre>
#define LISTING(x) PRAGMA(listing on #x)
#define PRAGMA(x) _Pragma(#x)
<a name="6.11" href="#6.11"><h3>6.11 Future language directions</h3></a>
<a name="6.11.1" href="#6.11.1"><h4>6.11.1 Floating types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Future standardization may include additional floating-point types, including those with
greater range, precision, or both than long double.
<a name="6.11.2" href="#6.11.2"><h4>6.11.2 Linkages of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Declaring an identifier with internal linkage at file scope without the static storage-
class specifier is an obsolescent feature.
<a name="6.11.3" href="#6.11.3"><h4>6.11.3 External names</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Restriction of the significance of an external name to fewer than 255 characters
(considering each universal character name or extended source character as a single
character) is an obsolescent feature that is a concession to existing implementations.
<a name="6.11.4" href="#6.11.4"><h4>6.11.4 Character escape sequences</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Lowercase letters as escape sequences are reserved for future standardization. Other
characters may be used in extensions.
<a name="6.11.5" href="#6.11.5"><h4>6.11.5 Storage-class specifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The placement of a storage-class specifier other than at the beginning of the declaration
specifiers in a declaration is an obsolescent feature.
<a name="6.11.6" href="#6.11.6"><h4>6.11.6 Function declarators</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The use of function declarators with empty parentheses (not prototype-format parameter
type declarators) is an obsolescent feature.
<a name="6.11.7" href="#6.11.7"><h4>6.11.7 Function definitions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The use of function definitions with separate parameter identifier and declaration lists
(not prototype-format parameter type and identifier declarators) is an obsolescent feature.
<a name="6.11.8" href="#6.11.8"><h4>6.11.8 Pragma directives</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Pragmas whose first preprocessing token is STDC are reserved for future standardization.
<a name="6.11.9" href="#6.11.9"><h4>6.11.9 Predefined macro names</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macro names beginning with __STDC_ are reserved for future standardization.
-<!--page 197 indent 4-->
+<!--page 197 -->
<a name="7" href="#7"><h2>7. Library</h2></a>
<a name="7.1" href="#7.1"><h3>7.1 Introduction</h3></a>
<a name="7.1.1" href="#7.1.1"><h4>7.1.1 Definitions of terms</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A string is a contiguous sequence of characters terminated by and including the first null
character. The term multibyte string is sometimes used instead to emphasize special
processing given to multibyte characters contained in the string or to avoid confusion
with a wide string. A pointer to a string is a pointer to its initial (lowest addressed)
character. The length of a string is the number of bytes preceding the null character and
the value of a string is the sequence of the values of the contained characters, in order.
-<p><!--para 2-->
+<p><!--para 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.<sup><a href="#note180"><b>180)</b></a></sup> It is represented in the text and examples by a period, but
may be changed by the setlocale function.
-<p><!--para 3-->
+<p><!--para 3 -->
A null wide character is a wide character with code value zero.
-<p><!--para 4-->
+<p><!--para 4 -->
A wide string is a contiguous sequence of wide characters terminated by and including
the first null wide character. A pointer to a wide string is a pointer to its initial (lowest
addressed) wide character. The length of a wide string is the number of wide characters
preceding the null wide character and the value of a wide string is the sequence of code
values of the contained wide characters, in order.
-<p><!--para 5-->
+<p><!--para 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
-<!--page 198 indent 4-->
+<!--page 198 -->
<h6>footnotes</h6>
<p><small><a name="note180" href="#note180">180)</a> The functions that make use of the decimal-point character are the numeric conversion functions
</small>
<a name="7.1.2" href="#7.1.2"><h4>7.1.2 Standard headers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Each library function is declared, with a type that includes a prototype, in a header,<sup><a href="#note182"><b>182)</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
include type qualifiers, unless explicitly stated otherwise.
-<p><!--para 2-->
+<p><!--para 2 -->
The standard headers are<sup><a href="#note183"><b>183)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
<a href="#7.2"><assert.h></a> <a href="#7.9"><iso646.h></a> <a href="#7.16"><stdarg.h></a> <a href="#7.23"><string.h></a>
<a href="#7.3"><complex.h></a> <a href="#7.10"><limits.h></a> <a href="#7.17"><stdatomic.h></a> <a href="#7.24"><tgmath.h></a>
If a file with the same name as one of the above < and > delimited sequences, not
provided as part of the implementation, is placed in any of the standard places that are
searched for included source files, the behavior is undefined.
-<p><!--para 4-->
+<p><!--para 4 -->
Standard headers may be included in any order; each may be included more than once in
a given scope, with no effect different from being included only once, except that the
effect of including <a href="#7.2"><assert.h></a> depends on the definition of NDEBUG (see <a href="#7.2">7.2</a>). If
included after the initial reference to the identifier. The program shall not have any
macros with names lexically identical to keywords currently defined prior to the
inclusion.
-<p><!--para 5-->
+<p><!--para 5 -->
Any definition of an object-like macro described in this clause shall expand to code that is
fully protected by parentheses where necessary, so that it groups in an arbitrary
expression as if it were a single identifier.
-<p><!--para 6-->
+<p><!--para 6 -->
Any declaration of a library function shall have external linkage.
-<!--page 199 indent 4-->
-<p><!--para 7-->
+<!--page 199 -->
+<p><!--para 7 -->
A summary of the contents of the standard headers is given in <a href="#B">annex B</a>.
<p><b> Forward references</b>: diagnostics (<a href="#7.2">7.2</a>).
</small>
<a name="7.1.3" href="#7.1.3"><h4>7.1.3 Reserved identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Each header declares or defines all identifiers listed in its associated subclause, and
optionally declares or defines identifiers listed in its associated future library directions
subclause and identifiers which are always reserved either for any use or for use as file
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.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
No other identifiers are reserved. If the program declares or defines an identifier in a
context in which it is reserved (other than as allowed by <a href="#7.1.4">7.1.4</a>), or defines a reserved
identifier as a macro name, the behavior is undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
If the program removes (with #undef) any macro definition of an identifier in the first
group listed above, the behavior is undefined.
-<!--page 200 indent 4-->
+<!--page 200 -->
<h6>footnotes</h6>
<p><small><a name="note184" href="#note184">184)</a> The list of reserved identifiers with external linkage includes math_errhandling, setjmp,
</small>
<a name="7.1.4" href="#7.1.4"><h4>7.1.4 Use of library functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Each of the following statements applies unless explicitly stated otherwise in the detailed
descriptions that follow: If an argument to a function has an invalid value (such as a value
outside the domain of the function, or a pointer outside the address space of the program,
compatible return type could be called.<sup><a href="#note187"><b>187)</b></a></sup> All object-like macros listed as expanding to
-<!--page 201 indent 4-->
+<!--page 201 -->
integer constant expressions shall additionally be suitable for use in #if preprocessing
directives.
-<p><!--para 2-->
+<p><!--para 2 -->
Provided that a library function can be declared without reference to any type defined in a
header, it is also permissible to declare the function and use it without including its
associated header.
-<p><!--para 3-->
+<p><!--para 3 -->
There is a sequence point immediately before a library function returns.
-<p><!--para 4-->
+<p><!--para 4 -->
The functions in the standard library are not guaranteed to be reentrant and may modify
objects with static or thread storage duration.<sup><a href="#note188"><b>188)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
Unless explicitly stated otherwise in the detailed descriptions that follow, library
functions shall prevent data races as follows: A library function shall not directly or
indirectly access objects accessible by threads other than the current thread unless the
the current thread unless the objects are accessed directly or indirectly via the function's
non-const arguments.<sup><a href="#note189"><b>189)</b></a></sup> Implementations may share their own internal objects between
threads if the objects are not visible to users and are protected against data races.
-<p><!--para 6-->
+<p><!--para 6 -->
Unless otherwise specified, library functions shall perform all operations solely within the
current thread if those operations have effects that are visible to users.<sup><a href="#note190"><b>190)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE The function atoi may be used in any of several ways:
<ul>
<li> by use of its associated header (possibly generating a macro expansion)
-<!--page 202 indent 0-->
+<!--page 202 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
#undef atoi
/* ... */
i = (atoi)(str);</pre>
<li> by explicit declaration
-<!--page 203 indent 4-->
+<!--page 203 -->
<pre>
extern int atoi(const char *);
const char *str;
</small>
<a name="7.2" href="#7.2"><h3>7.2 Diagnostics <assert.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.2"><assert.h></a> defines the assert and static_assert macros and
refers to another macro,
<pre>
#define assert(ignore) ((void)0)</pre>
The assert macro is redefined according to the current state of NDEBUG each time that
<a href="#7.2"><assert.h></a> is included.
-<p><!--para 2-->
+<p><!--para 2 -->
The assert macro shall be implemented as a macro, not as an actual function. If the
macro definition is suppressed in order to access an actual function, the behavior is
undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
The macro
<pre>
static_assert</pre>
<a name="7.2.1.1" href="#7.2.1.1"><h5>7.2.1.1 The assert macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.2"><assert.h></a>
void assert(scalar expression);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The assert macro puts diagnostic tests into programs; it expands to a void expression.
When it is executed, if expression (which shall have a scalar type) is false (that is,
compares equal to 0), the assert macro writes information about the particular call that
-<!--page 204 indent 4-->
+<!--page 204 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The assert macro returns no value.
<p><b> Forward references</b>: the abort function (<a href="#7.22.4.1">7.22.4.1</a>).
-<!--page 205 indent 4-->
+<!--page 205 -->
<h6>footnotes</h6>
<p><small><a name="note191" href="#note191">191)</a> The message written might be of the form:
<a name="7.3" href="#7.3"><h3>7.3 Complex arithmetic <complex.h></h3></a>
<a name="7.3.1" href="#7.3.1"><h4>7.3.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.3"><complex.h></a> defines macros and declares functions that support complex
arithmetic.<sup><a href="#note192"><b>192)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
Implementations that define the macro __STDC_NO_COMPLEX__ need not provide
this header nor support any of its facilities.
-<p><!--para 3-->
+<p><!--para 3 -->
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 return values.
-<p><!--para 4-->
+<p><!--para 4 -->
The macro
<pre>
complex</pre>
_Complex_I</pre>
expands to a constant expression of type const float _Complex, with the value of
the imaginary unit.<sup><a href="#note193"><b>193)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
The macros
<pre>
imaginary</pre>
are defined if and only if the implementation supports imaginary types;<sup><a href="#note194"><b>194)</b></a></sup> if defined,
they expand to _Imaginary and a constant expression of type const float
_Imaginary with the value of the imaginary unit.
-<p><!--para 6-->
+<p><!--para 6 -->
The macro
<pre>
I</pre>
expands to either _Imaginary_I or _Complex_I. If _Imaginary_I is not
defined, I shall expand to _Complex_I.
-<p><!--para 7-->
+<p><!--para 7 -->
Notwithstanding the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and perhaps then
redefine the macros complex, imaginary, and I.
-<!--page 206 indent 4-->
+<!--page 206 -->
<p><b> Forward references</b>: IEC 60559-compatible complex arithmetic (<a href="#G">annex G</a>).
<h6>footnotes</h6>
</small>
<a name="7.3.2" href="#7.3.2"><h4>7.3.2 Conventions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Values are interpreted as radians, not degrees. An implementation may set errno but is
not required to.
<a name="7.3.3" href="#7.3.3"><h4>7.3.3 Branch cuts</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Some of the functions below have branch cuts, across which the function is
discontinuous. For implementations with a signed zero (including all IEC 60559
implementations) that follow the specifications of <a href="#G">annex G</a>, the sign of zero distinguishes
function, which has a branch cut along the negative real axis, the top of the cut, with
imaginary part +0, maps to the positive imaginary axis, and the bottom of the cut, with
imaginary part -0, maps to the negative imaginary axis.
-<p><!--para 2-->
+<p><!--para 2 -->
Implementations that do not support a signed zero (see <a href="#F">annex F</a>) cannot distinguish the
sides of branch cuts. These implementations shall map a cut so the function is continuous
as the cut is approached coming around the finite endpoint of the cut in a counter
<a name="7.3.4" href="#7.3.4"><h4>7.3.4 The CX_LIMITED_RANGE pragma</h4></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
#pragma STDC CX_LIMITED_RANGE on-off-switch</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The usual mathematical formulas for complex multiply, divide, and absolute value are
problematic because of their treatment of infinities and because of undue overflow and
underflow. The CX_LIMITED_RANGE pragma can be used to inform the
another CX_LIMITED_RANGE pragma is encountered (including within a nested
compound statement), or until the end of the compound statement; at the end of a
compound statement the state for the pragma is restored to its condition just before the
-<!--page 207 indent 4-->
+<!--page 207 -->
compound statement. If this pragma is used in any other context, the behavior is
undefined. The default state for the pragma is ''off''.
<a name="7.3.5.1" href="#7.3.5.1"><h5>7.3.5.1 The cacos functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacos(double complex z);
float complex cacosf(float complex z);
long double complex cacosl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cacos functions compute the complex arc cosine of z, with branch cuts outside the
interval [-1, +1] along the real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cacos functions return the complex arc cosine value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [0, pi ] along the
real axis.
<a name="7.3.5.2" href="#7.3.5.2"><h5>7.3.5.2 The casin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casin(double complex z);
float complex casinf(float complex z);
long double complex casinl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The casin functions compute the complex arc sine of z, with branch cuts outside the
interval [-1, +1] along the real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The casin functions return the complex arc sine value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
-<!--page 208 indent 4-->
+<!--page 208 -->
along the real axis.
<a name="7.3.5.3" href="#7.3.5.3"><h5>7.3.5.3 The catan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catan(double complex z);
float complex catanf(float complex z);
long double complex catanl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The catan functions compute the complex arc tangent of z, with branch cuts outside the
interval [-i, +i] along the imaginary axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The catan functions return the complex arc tangent value, in the range of a strip
mathematically unbounded along the imaginary axis and in the interval [-pi /2, +pi /2]
along the real axis.
<a name="7.3.5.4" href="#7.3.5.4"><h5>7.3.5.4 The ccos functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccos(double complex z);
float complex ccosf(float complex z);
long double complex ccosl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ccos functions compute the complex cosine of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ccos functions return the complex cosine value.
<a name="7.3.5.5" href="#7.3.5.5"><h5>7.3.5.5 The csin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csin(double complex z);
float complex csinf(float complex z);
long double complex csinl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The csin functions compute the complex sine of z.
-<!--page 209 indent 4-->
+<!--page 209 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The csin functions return the complex sine value.
<a name="7.3.5.6" href="#7.3.5.6"><h5>7.3.5.6 The ctan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctan(double complex z);
float complex ctanf(float complex z);
long double complex ctanl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ctan functions compute the complex tangent of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ctan functions return the complex tangent value.
<a name="7.3.6" href="#7.3.6"><h4>7.3.6 Hyperbolic functions</h4></a>
<a name="7.3.6.1" href="#7.3.6.1"><h5>7.3.6.1 The cacosh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cacosh(double complex z);
float complex cacoshf(float complex z);
long double complex cacoshl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cacosh functions compute the complex arc hyperbolic cosine of z, with a branch
cut at values less than 1 along the real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cacosh functions return the complex arc hyperbolic cosine value, in the range of a
half-strip of nonnegative values along the real axis and in the interval [-ipi , +ipi ] along the
imaginary axis.
<a name="7.3.6.2" href="#7.3.6.2"><h5>7.3.6.2 The casinh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 210 indent 4-->
+<p><!--para 1 -->
+<!--page 210 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex casinh(double complex z);
float complex casinhf(float complex z);
long double complex casinhl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The casinh functions compute the complex arc hyperbolic sine of z, with branch cuts
outside the interval [-i, +i] along the imaginary axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The casinh functions return the complex arc hyperbolic sine value, in the range of a
strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
along the imaginary axis.
<a name="7.3.6.3" href="#7.3.6.3"><h5>7.3.6.3 The catanh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex catanh(double complex z);
float complex catanhf(float complex z);
long double complex catanhl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The catanh functions compute the complex arc hyperbolic tangent of z, with branch
cuts outside the interval [-1, +1] along the real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The catanh functions return the complex arc hyperbolic tangent value, in the range of a
strip mathematically unbounded along the real axis and in the interval [-ipi /2, +ipi /2]
along the imaginary axis.
<a name="7.3.6.4" href="#7.3.6.4"><h5>7.3.6.4 The ccosh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ccosh(double complex z);
float complex ccoshf(float complex z);
long double complex ccoshl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ccosh functions compute the complex hyperbolic cosine of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ccosh functions return the complex hyperbolic cosine value.
-<!--page 211 indent 4-->
+<!--page 211 -->
<a name="7.3.6.5" href="#7.3.6.5"><h5>7.3.6.5 The csinh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csinh(double complex z);
float complex csinhf(float complex z);
long double complex csinhl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The csinh functions compute the complex hyperbolic sine of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The csinh functions return the complex hyperbolic sine value.
<a name="7.3.6.6" href="#7.3.6.6"><h5>7.3.6.6 The ctanh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex ctanh(double complex z);
float complex ctanhf(float complex z);
long double complex ctanhl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ctanh functions compute the complex hyperbolic tangent of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ctanh functions return the complex hyperbolic tangent value.
<a name="7.3.7" href="#7.3.7"><h4>7.3.7 Exponential and logarithmic functions</h4></a>
<a name="7.3.7.1" href="#7.3.7.1"><h5>7.3.7.1 The cexp functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cexp(double complex z);
float complex cexpf(float complex z);
long double complex cexpl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cexp functions compute the complex base-e exponential of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cexp functions return the complex base-e exponential value.
-<!--page 212 indent 4-->
+<!--page 212 -->
<a name="7.3.7.2" href="#7.3.7.2"><h5>7.3.7.2 The clog functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex clog(double complex z);
float complex clogf(float complex z);
long double complex clogl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The clog functions compute the complex natural (base-e) logarithm of z, with a branch
cut along the negative real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The clog functions return the complex natural logarithm value, in the range of a strip
mathematically unbounded along the real axis and in the interval [-ipi , +ipi ] along the
imaginary axis.
<a name="7.3.8.1" href="#7.3.8.1"><h5>7.3.8.1 The cabs functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cabs(double complex z);
float cabsf(float complex z);
long double cabsl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cabs functions compute the complex absolute value (also called norm, modulus, or
magnitude) of z.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cabs functions return the complex absolute value.
<a name="7.3.8.2" href="#7.3.8.2"><h5>7.3.8.2 The cpow functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 213 indent 4-->
+<p><!--para 1 -->
+<!--page 213 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cpow(double complex x, double complex y);
long double complex cpowl(long double complex x,
long double complex y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cpow functions compute the complex power function xy , with a branch cut for the
first parameter along the negative real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cpow functions return the complex power function value.
<a name="7.3.8.3" href="#7.3.8.3"><h5>7.3.8.3 The csqrt functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex csqrt(double complex z);
float complex csqrtf(float complex z);
long double complex csqrtl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The csqrt functions compute the complex square root of z, with a branch cut along the
negative real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The csqrt functions return the complex square root value, in the range of the right half-
plane (including the imaginary axis).
<a name="7.3.9.1" href="#7.3.9.1"><h5>7.3.9.1 The carg functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double carg(double complex z);
float cargf(float complex z);
long double cargl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The carg functions compute the argument (also called phase angle) of z, with a branch
cut along the negative real axis.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The carg functions return the value of the argument in the interval [-pi , +pi ].
-<!--page 214 indent 4-->
+<!--page 214 -->
<a name="7.3.9.2" href="#7.3.9.2"><h5>7.3.9.2 The cimag functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double cimag(double complex z);
float cimagf(float complex z);
long double cimagl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cimag functions compute the imaginary part of z.<sup><a href="#note196"><b>196)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cimag functions return the imaginary part value (as a real).
<h6>footnotes</h6>
<a name="7.3.9.3" href="#7.3.9.3"><h5>7.3.9.3 The CMPLX macros</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex CMPLX(double x, double y);
float complex CMPLXF(float x, float y);
long double complex CMPLXL(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The CMPLX macros expand to an expression of the specified complex type, with the real
part having the (converted) value of x and the imaginary part having the (converted)
value of y.
Recommended practice
-<p><!--para 3-->
+<p><!--para 3 -->
The resulting expression should be suitable for use as an initializer for an object with
static or thread storage duration, provided both arguments are likewise suitable.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The CMPLX macros return the complex value x + i y.
-<p><!--para 5-->
+<p><!--para 5 -->
NOTE These macros act as if the implementation supported imaginary types and the definitions were:
<pre>
#define CMPLX(x, y) ((double complex)((double)(x) + \
-<!--page 215 indent 4-->
+<!--page 215 -->
<a name="7.3.9.4" href="#7.3.9.4"><h5>7.3.9.4 The conj functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex conj(double complex z);
float complex conjf(float complex z);
long double complex conjl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The conj functions compute the complex conjugate of z, by reversing the sign of its
imaginary part.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The conj functions return the complex conjugate value.
<a name="7.3.9.5" href="#7.3.9.5"><h5>7.3.9.5 The cproj functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double complex cproj(double complex z);
float complex cprojf(float complex z);
long double complex cprojl(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cproj functions compute a projection of z onto the Riemann sphere: z projects to
z except that all complex infinities (even those with one infinite part and one NaN part)
project to positive infinity on the real axis. If z has an infinite part, then cproj(z) is
<pre>
INFINITY + I * copysign(0.0, cimag(z))</pre>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cproj functions return the value of the projection onto the Riemann sphere.
<a name="7.3.9.6" href="#7.3.9.6"><h5>7.3.9.6 The creal functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.3"><complex.h></a>
double creal(double complex z);
float crealf(float complex z);
long double creall(long double complex z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The creal functions compute the real part of z.<sup><a href="#note197"><b>197)</b></a></sup>
-<!--page 216 indent 4-->
+<!--page 216 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The creal functions return the real part value.
-<!--page 217 indent 4-->
+<!--page 217 -->
<h6>footnotes</h6>
<p><small><a name="note197" href="#note197">197)</a> For a variable z of complex type, z == creal(z) + cimag(z)*I.
</small>
<a name="7.4" href="#7.4"><h3>7.4 Character handling <ctype.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.4"><ctype.h></a> declares several functions useful for classifying and mapping
characters.<sup><a href="#note198"><b>198)</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.
-<p><!--para 2-->
+<p><!--para 2 -->
The behavior of these functions is affected by the current locale. Those functions that
have locale-specific aspects only when not in the "C" locale are noted below.
-<p><!--para 3-->
+<p><!--para 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
</small>
<a name="7.4.1" href="#7.4.1"><h4>7.4.1 Character classification functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions in this subclause return nonzero (true) if and only if the value of the
argument c conforms to that in the description of the function.
<a name="7.4.1.1" href="#7.4.1.1"><h5>7.4.1.1 The isalnum function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isalnum(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isalnum function tests for any character for which isalpha or isdigit is true.
<a name="7.4.1.2" href="#7.4.1.2"><h5>7.4.1.2 The isalpha function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isalpha(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isalpha function tests for any character for which isupper or islower is true,
or any character that is one of a locale-specific set of alphabetic characters for which
-<!--page 218 indent 4-->
+<!--page 218 -->
none of iscntrl, isdigit, ispunct, or isspace is true.<sup><a href="#note200"><b>200)</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"><h5>7.4.1.3 The isblank function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isblank(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isblank function tests for any character that is a standard blank character or is one
of a locale-specific set of characters for which isspace is true and that is used to
separate words within a line of text. The standard blank characters are the following:
<a name="7.4.1.4" href="#7.4.1.4"><h5>7.4.1.4 The iscntrl function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int iscntrl(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iscntrl function tests for any control character.
<a name="7.4.1.5" href="#7.4.1.5"><h5>7.4.1.5 The isdigit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isdigit(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isdigit function tests for any decimal-digit character (as defined in <a href="#5.2.1">5.2.1</a>).
<a name="7.4.1.6" href="#7.4.1.6"><h5>7.4.1.6 The isgraph function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isgraph(int c);</pre>
-<!--page 219 indent 4-->
+<!--page 219 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isgraph function tests for any printing character except space (' ').
<a name="7.4.1.7" href="#7.4.1.7"><h5>7.4.1.7 The islower function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int islower(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The islower function tests for any character that is a lowercase letter or is one of a
locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
isspace is true. In the "C" locale, islower returns true only for the lowercase
<a name="7.4.1.8" href="#7.4.1.8"><h5>7.4.1.8 The isprint function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isprint(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isprint function tests for any printing character including space (' ').
<a name="7.4.1.9" href="#7.4.1.9"><h5>7.4.1.9 The ispunct function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int ispunct(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ispunct function tests for any printing character that is one of a locale-specific set
of punctuation characters for which neither isspace nor isalnum is true. In the "C"
locale, ispunct returns true for every printing character for which neither isspace
<a name="7.4.1.10" href="#7.4.1.10"><h5>7.4.1.10 The isspace function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isspace(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isspace function tests for any character that is a standard white-space character or
is one of a locale-specific set of characters for which isalnum is false. The standard
-<!--page 220 indent 4-->
+<!--page 220 -->
white-space characters are the following: space (' '), form feed ('\f'), new-line
('\n'), carriage return ('\r'), horizontal tab ('\t'), and vertical tab ('\v'). In the
"C" locale, isspace returns true only for the standard white-space characters.
<a name="7.4.1.11" href="#7.4.1.11"><h5>7.4.1.11 The isupper function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isupper(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isupper function tests for any character that is an uppercase letter or is one of a
locale-specific set of characters for which none of iscntrl, isdigit, ispunct, or
isspace is true. In the "C" locale, isupper returns true only for the uppercase
<a name="7.4.1.12" href="#7.4.1.12"><h5>7.4.1.12 The isxdigit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int isxdigit(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isxdigit function tests for any hexadecimal-digit character (as defined in <a href="#6.4.4.1">6.4.4.1</a>).
<a name="7.4.2" href="#7.4.2"><h4>7.4.2 Character case mapping functions</h4></a>
<a name="7.4.2.1" href="#7.4.2.1"><h5>7.4.2.1 The tolower function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int tolower(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tolower function converts an uppercase letter to a corresponding lowercase letter.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a character for which isupper is true and there are one or more
corresponding characters, as specified by the current locale, for which islower is true,
the tolower function returns one of the corresponding characters (always the same one
for any given locale); otherwise, the argument is returned unchanged.
-<!--page 221 indent 4-->
+<!--page 221 -->
<a name="7.4.2.2" href="#7.4.2.2"><h5>7.4.2.2 The toupper function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.4"><ctype.h></a>
int toupper(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The toupper function converts a lowercase letter to a corresponding uppercase letter.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a character for which islower is true and there are one or more
corresponding characters, as specified by the current locale, for which isupper is true,
the toupper function returns one of the corresponding characters (always the same one
for any given locale); otherwise, the argument is returned unchanged.
-<!--page 222 indent 4-->
+<!--page 222 -->
<a name="7.5" href="#7.5"><h3>7.5 Errors <errno.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.5"><errno.h></a> defines several macros, all relating to the reporting of error
conditions.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros are
<pre>
EDOM
duration, the value of which is set to a positive error number by several library functions.
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.
-<p><!--para 3-->
+<p><!--para 3 -->
The value of errno in the initial thread is zero at program startup (the initial value of
errno in other threads is an indeterminate value), but is never set to zero by any library
function.<sup><a href="#note202"><b>202)</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.
-<p><!--para 4-->
+<p><!--para 4 -->
Additional macro definitions, beginning with E and a digit or E and an uppercase
letter,<sup><a href="#note203"><b>203)</b></a></sup> may also be specified by the implementation.
-<!--page 223 indent 4-->
+<!--page 223 -->
<h6>footnotes</h6>
<p><small><a name="note201" href="#note201">201)</a> The macro errno need not be the identifier of an object. It might expand to a modifiable lvalue
</small>
<a name="7.6" href="#7.6"><h3>7.6 Floating-point environment <fenv.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.6"><fenv.h></a> defines several macros, and declares types and functions that
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
of exceptional floating-point arithmetic to provide auxiliary information.<sup><a href="#note205"><b>205)</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.
-<p><!--para 2-->
+<p><!--para 2 -->
The floating-point environment has thread storage duration. The initial state for a
thread's floating-point environment is the current state of the floating-point environment
of the thread that creates it at the time of creation.
-<p><!--para 3-->
+<p><!--para 3 -->
Certain programming conventions support the intended model of use for the floating-
point environment:<sup><a href="#note206"><b>206)</b></a></sup>
<ul>
<li> a function call is assumed to have the potential for raising floating-point exceptions,
unless its documentation promises otherwise.
</ul>
-<p><!--para 4-->
+<p><!--para 4 -->
The type
<pre>
fenv_t</pre>
represents the entire floating-point environment.
-<p><!--para 5-->
+<p><!--para 5 -->
The type
<pre>
fexcept_t</pre>
implementation associates with the flags.
-<!--page 224 indent 4-->
-<p><!--para 6-->
+<!--page 224 -->
+<p><!--para 6 -->
Each of the macros
<pre>
FE_DIVBYZERO
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.<sup><a href="#note208"><b>208)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 7 -->
The macro
<pre>
FE_ALL_EXCEPT</pre>
is simply the bitwise OR of all floating-point exception macros defined by the
implementation. If no such macros are defined, FE_ALL_EXCEPT shall be defined as 0.
-<p><!--para 8-->
+<p><!--para 8 -->
Each of the macros
<pre>
FE_DOWNWARD
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.<sup><a href="#note209"><b>209)</b></a></sup>
-<p><!--para 9-->
+<p><!--para 9 -->
The macro
-<!--page 225 indent 5-->
+<!--page 225 -->
<pre>
FE_DFL_ENV</pre>
represents the default floating-point environment -- the one installed at program startup
<li> and has type ''pointer to const-qualified fenv_t''. It can be used as an argument to
</ul>
<a href="#7.6"><fenv.h></a> functions that manage the floating-point environment.
-<p><!--para 10-->
+<p><!--para 10 -->
Additional implementation-defined environments, with macro definitions beginning with
FE_ and an uppercase letter, and having type ''pointer to const-qualified fenv_t'', may
also be specified by the implementation.
<a name="7.6.1" href="#7.6.1"><h4>7.6.1 The FENV_ACCESS pragma</h4></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS on-off-switch</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The FENV_ACCESS pragma provides a means to inform the implementation when a
program might access the floating-point environment to test floating-point status flags or
run under non-default floating-point control modes.<sup><a href="#note210"><b>210)</b></a></sup> The pragma shall occur either
-<!--page 226 indent 4-->
-<p><!--para 3-->
+<!--page 226 -->
+<p><!--para 3 -->
EXAMPLE
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
void f(double x)
</small>
<a name="7.6.2" href="#7.6.2"><h4>7.6.2 Floating-point exceptions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following functions provide access to the floating-point status flags.<sup><a href="#note212"><b>212)</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
<a name="7.6.2.1" href="#7.6.2.1"><h5>7.6.2.1 The feclearexcept function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int feclearexcept(int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feclearexcept function attempts to clear the supported floating-point exceptions
represented by its argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feclearexcept function returns zero if the excepts argument is zero or if all
the specified exceptions were successfully cleared. Otherwise, it returns a nonzero value.
-<!--page 227 indent 4-->
+<!--page 227 -->
<a name="7.6.2.2" href="#7.6.2.2"><h5>7.6.2.2 The fegetexceptflag function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetexceptflag(fexcept_t *flagp,
int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fegetexceptflag function attempts to store an implementation-defined
representation of the states of the floating-point status flags indicated by the argument
excepts in the object pointed to by the argument flagp.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fegetexceptflag function returns zero if the representation was successfully
stored. Otherwise, it returns a nonzero value.
<a name="7.6.2.3" href="#7.6.2.3"><h5>7.6.2.3 The feraiseexcept function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int feraiseexcept(int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feraiseexcept function attempts to raise the supported floating-point exceptions
represented by its argument.<sup><a href="#note213"><b>213)</b></a></sup> The order in which these floating-point exceptions are
raised is unspecified, except as stated in <a href="#F.8.6">F.8.6</a>. Whether the feraiseexcept function
additionally raises the ''inexact'' floating-point exception whenever it raises the
''overflow'' or ''underflow'' floating-point exception is implementation-defined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feraiseexcept function returns zero if the excepts argument is zero or if all
the specified exceptions were successfully raised. Otherwise, it returns a nonzero value.
-<!--page 228 indent 4-->
+<!--page 228 -->
<h6>footnotes</h6>
<p><small><a name="note213" href="#note213">213)</a> The effect is intended to be similar to that of floating-point exceptions raised by arithmetic operations.
<a name="7.6.2.4" href="#7.6.2.4"><h5>7.6.2.4 The fesetexceptflag function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetexceptflag(const fexcept_t *flagp,
int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fesetexceptflag function attempts to set the floating-point status flags
indicated by the argument excepts to the states stored in the object pointed to by
flagp. The value of *flagp shall have been set by a previous call to
exceptions represented by the argument excepts. This function does not raise floating-
point exceptions, but only sets the state of the flags.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fesetexceptflag function returns zero if the excepts argument is zero or if
all the specified flags were successfully set to the appropriate state. Otherwise, it returns
a nonzero value.
<a name="7.6.2.5" href="#7.6.2.5"><h5>7.6.2.5 The fetestexcept function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fetestexcept(int excepts);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fetestexcept function determines which of a specified subset of the floating-
point exception flags are currently set. The excepts argument specifies the floating-
point status flags to be queried.<sup><a href="#note214"><b>214)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fetestexcept function returns the value of the bitwise OR of the floating-point
exception macros corresponding to the currently set floating-point exceptions included in
excepts.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE Call f if ''invalid'' is set, then g if ''overflow'' is set:
-<!--page 229 indent 4-->
+<!--page 229 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
/* ... */
</small>
<a name="7.6.3" href="#7.6.3"><h4>7.6.3 Rounding</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The fegetround and fesetround functions provide control of rounding direction
modes.
<a name="7.6.3.1" href="#7.6.3.1"><h5>7.6.3.1 The fegetround function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetround(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fegetround function gets the current rounding direction.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fegetround function returns the value of the rounding direction macro
representing the current rounding direction or a negative value if there is no such
rounding direction macro or the current rounding direction is not determinable.
<a name="7.6.3.2" href="#7.6.3.2"><h5>7.6.3.2 The fesetround function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetround(int round);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fesetround function establishes the rounding direction represented by its
argument round. If the argument is not equal to the value of a rounding direction macro,
the rounding direction is not changed.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fesetround function returns zero if and only if the requested rounding direction
was established.
-<!--page 230 indent 4-->
-<p><!--para 4-->
+<!--page 230 -->
+<p><!--para 4 -->
EXAMPLE Save, set, and restore the rounding direction. Report an error and abort if setting the
rounding direction fails.
<pre>
<a name="7.6.4" href="#7.6.4"><h4>7.6.4 Environment</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions in this section manage the floating-point environment -- status flags and
control modes -- as one entity.
<a name="7.6.4.1" href="#7.6.4.1"><h5>7.6.4.1 The fegetenv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fegetenv(fenv_t *envp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fegetenv function attempts to store the current floating-point environment in the
object pointed to by envp.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fegetenv function returns zero if the environment was successfully stored.
Otherwise, it returns a nonzero value.
<a name="7.6.4.2" href="#7.6.4.2"><h5>7.6.4.2 The feholdexcept function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int feholdexcept(fenv_t *envp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feholdexcept function saves the current floating-point environment in the object
pointed to by envp, clears the floating-point status flags, and then installs a non-stop
(continue on floating-point exceptions) mode, if available, for all floating-point
exceptions.<sup><a href="#note215"><b>215)</b></a></sup>
-<!--page 231 indent 4-->
+<!--page 231 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feholdexcept function returns zero if and only if non-stop floating-point
exception handling was successfully installed.
<a name="7.6.4.3" href="#7.6.4.3"><h5>7.6.4.3 The fesetenv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int fesetenv(const fenv_t *envp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fesetenv function attempts to establish the floating-point environment represented
by the object pointed to by envp. The argument envp shall point to an object set by a
call to fegetenv or feholdexcept, or equal a floating-point environment macro.
Note that fesetenv merely installs the state of the floating-point status flags
represented through its argument, and does not raise these floating-point exceptions.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fesetenv function returns zero if the environment was successfully established.
Otherwise, it returns a nonzero value.
<a name="7.6.4.4" href="#7.6.4.4"><h5>7.6.4.4 The feupdateenv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
int feupdateenv(const fenv_t *envp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feupdateenv function attempts to save the currently raised floating-point
exceptions in its automatic storage, install the floating-point environment represented by
the object pointed to by envp, and then raise the saved floating-point exceptions. The
argument envp shall point to an object set by a call to feholdexcept or fegetenv,
or equal a floating-point environment macro.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feupdateenv function returns zero if all the actions were successfully carried out.
Otherwise, it returns a nonzero value.
-<!--page 232 indent 4-->
-<p><!--para 4-->
+<!--page 232 -->
+<p><!--para 4 -->
EXAMPLE Hide spurious underflow floating-point exceptions:
-<!--page 233 indent 4-->
+<!--page 233 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
double f(double x)
}</pre>
<a name="7.7" href="#7.7"><h3>7.7 Characteristics of floating types <float.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.7"><float.h></a> defines several macros that expand to various limits and
parameters of the standard floating-point types.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros, their meanings, and the constraints (or restrictions) on their values are listed
in <a href="#5.2.4.2.2">5.2.4.2.2</a>.
-<!--page 234 indent 4-->
+<!--page 234 -->
<a name="7.8" href="#7.8"><h3>7.8 Format conversion of integer types <inttypes.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.8"><inttypes.h></a> includes the header <a href="#7.20"><stdint.h></a> and extends it with
additional facilities provided by hosted implementations.
-<p><!--para 2-->
+<p><!--para 2 -->
It declares functions for manipulating greatest-width integers and converting numeric
character strings to greatest-width integers, and it declares the type
<pre>
</small>
<a name="7.8.1" href="#7.8.1"><h4>7.8.1 Macros for format specifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Each of the following object-like macros 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
name corresponding to a similar type name in <a href="#7.20.1">7.20.1</a>. In these names, N represents the
width of the type as described in <a href="#7.20.1">7.20.1</a>. For example, PRIdFAST32 can be used in a
format string to print the value of an integer of type int_fast32_t.
-<p><!--para 2-->
+<p><!--para 2 -->
The fprintf macros for signed integers are:
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR
PRIiN PRIiLEASTN PRIiFASTN PRIiMAX PRIiPTR</pre>
The fprintf macros for unsigned integers are:
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
PRIoN PRIoLEASTN PRIoFASTN PRIoMAX PRIoPTR
PRIuN PRIuLEASTN PRIuFASTN PRIuMAX PRIuPTR
-<!--page 235 indent 4-->
-<p><!--para 5-->
+<!--page 235 -->
+<p><!--para 5 -->
<pre>
SCNdN SCNdLEASTN SCNdFASTN SCNdMAX SCNdPTR
SCNiN SCNiLEASTN SCNiFASTN SCNiMAX SCNiPTR</pre>
The fscanf macros for unsigned integers are:
-<p><!--para 6-->
+<p><!--para 6 -->
<pre>
SCNoN SCNoLEASTN SCNoFASTN SCNoMAX SCNoPTR
SCNuN SCNuLEASTN SCNuFASTN SCNuMAX SCNuPTR
fprintf macros shall be defined and the corresponding fscanf macros shall be
defined unless the implementation does not have a suitable fscanf length modifier for
the type.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE
<pre>
#include <a href="#7.8"><inttypes.h></a>
<a name="7.8.2.1" href="#7.8.2.1"><h5>7.8.2.1 The imaxabs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
intmax_t imaxabs(intmax_t j);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The imaxabs function computes the absolute value of an integer j. If the result cannot
be represented, the behavior is undefined.<sup><a href="#note218"><b>218)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The imaxabs function returns the absolute value.
-<!--page 236 indent 4-->
+<!--page 236 -->
<h6>footnotes</h6>
<p><small><a name="note218" href="#note218">218)</a> The absolute value of the most negative number cannot be represented in two's complement.
<a name="7.8.2.2" href="#7.8.2.2"><h5>7.8.2.2 The imaxdiv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The imaxdiv function computes numer / denom and numer % denom in a single
operation.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The imaxdiv function returns a structure of type imaxdiv_t comprising both the
quotient and the remainder. The structure shall contain (in either order) the members
quot (the quotient) and rem (the remainder), each of which has type intmax_t. If
<a name="7.8.2.3" href="#7.8.2.3"><h5>7.8.2.3 The strtoimax and strtoumax functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.8"><inttypes.h></a>
intmax_t strtoimax(const char * restrict nptr,
uintmax_t strtoumax(const char * restrict nptr,
char ** restrict endptr, int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strtoimax and strtoumax functions are equivalent to the strtol, strtoll,
strtoul, and strtoull functions, except that the initial portion of the string is
converted to intmax_t and uintmax_t representation, respectively.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strtoimax and strtoumax functions return the converted value, if any. If no
conversion could be performed, zero is returned. If the correct value is outside the range
of representable values, INTMAX_MAX, INTMAX_MIN, or UINTMAX_MAX is returned
ERANGE is stored in errno.
<p><b> Forward references</b>: the strtol, strtoll, strtoul, and strtoull functions
(<a href="#7.22.1.4">7.22.1.4</a>).
-<!--page 237 indent 4-->
+<!--page 237 -->
<a name="7.8.2.4" href="#7.8.2.4"><h5>7.8.2.4 The wcstoimax and wcstoumax functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.19"><stddef.h></a> // for wchar_t
#include <a href="#7.8"><inttypes.h></a>
uintmax_t wcstoumax(const wchar_t * restrict nptr,
wchar_t ** restrict endptr, int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcstoimax and wcstoumax functions are equivalent to the wcstol, wcstoll,
wcstoul, and wcstoull functions except that the initial portion of the wide string is
converted to intmax_t and uintmax_t representation, respectively.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcstoimax function returns the converted value, if any. If no conversion could be
performed, zero is returned. If the correct value is outside the range of representable
values, INTMAX_MAX, INTMAX_MIN, or UINTMAX_MAX is returned (according to the
errno.
<p><b> Forward references</b>: the wcstol, wcstoll, wcstoul, and wcstoull functions
(<a href="#7.28.4.1.2">7.28.4.1.2</a>).
-<!--page 238 indent 4-->
+<!--page 238 -->
<a name="7.9" href="#7.9"><h3>7.9 Alternative spellings <iso646.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.9"><iso646.h></a> defines the following eleven macros (on the left) that expand
to the corresponding tokens (on the right):
-<!--page 239 indent 4-->
+<!--page 239 -->
<pre>
and &&
and_eq &=
xor_eq ^=</pre>
<a name="7.10" href="#7.10"><h3>7.10 Sizes of integer types <limits.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.10"><limits.h></a> defines several macros that expand to various limits and
parameters of the standard integer types.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros, their meanings, and the constraints (or restrictions) on their values are listed
in <a href="#5.2.4.2.1">5.2.4.2.1</a>.
-<!--page 240 indent 4-->
+<!--page 240 -->
<a name="7.11" href="#7.11"><h3>7.11 Localization <locale.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.11"><locale.h></a> declares two functions, one type, and defines several macros.
-<p><!--para 2-->
+<p><!--para 2 -->
The type is
<pre>
struct lconv</pre>
contain at least the following members, in any order. The semantics of the members and
their normal ranges are explained in <a href="#7.11.2.1">7.11.2.1</a>. In the "C" locale, the members shall have
the values specified in the comments.
-<!--page 241 indent 4-->
-<p><!--para 3-->
+<!--page 241 -->
+<p><!--para 3 -->
<pre>
char *decimal_point; // "."
char *thousands_sep; // ""
<a name="7.11.1.1" href="#7.11.1.1"><h5>7.11.1.1 The setlocale function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.11"><locale.h></a>
char *setlocale(int category, const char *locale);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The setlocale function selects the appropriate portion of the program's locale as
specified by the category and locale arguments. The setlocale function may be
used to change or query the program's entire current locale or portions thereof. The value
formatted input/output functions and the string conversion functions, as well as the
nonmonetary formatting information returned by the localeconv function. LC_TIME
affects the behavior of the strftime and wcsftime functions.
-<p><!--para 3-->
+<p><!--para 3 -->
A value of "C" for locale specifies the minimal environment for C translation; a value
of "" for locale specifies the locale-specific native environment. Other
implementation-defined strings may be passed as the second argument to setlocale.
-<!--page 242 indent 4-->
-<p><!--para 4-->
+<!--page 242 -->
+<p><!--para 4 -->
At program startup, the equivalent of
<pre>
setlocale(LC_ALL, "C");</pre>
is executed.
-<p><!--para 5-->
+<p><!--para 5 -->
A call to the setlocale function may introduce a data race with other calls to the
setlocale function or with calls to functions that are affected by the current locale.
The implementation shall behave as if no library function calls the setlocale function.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
If a pointer to a string is given for locale and the selection can be honored, the
setlocale function returns a pointer to the string associated with the specified
category for the new locale. If the selection cannot be honored, the setlocale
function returns a null pointer and the program's locale is not changed.
-<p><!--para 7-->
+<p><!--para 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.<sup><a href="#note222"><b>222)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 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
<a name="7.11.2.1" href="#7.11.2.1"><h5>7.11.2.1 The localeconv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.11"><locale.h></a>
struct lconv *localeconv(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The localeconv function sets the components of an object with type struct lconv
with values appropriate for the formatting of numeric quantities (monetary and otherwise)
according to the rules of the current locale.
-<!--page 243 indent 4-->
-<p><!--para 3-->
+<!--page 243 -->
+<p><!--para 3 -->
The members of the structure with type char * are pointers to strings, any of which
(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
The number of fractional digits (those after the decimal-point) to be
displayed in a locally formatted monetary quantity.</pre>
char p_cs_precedes
-<!--page 244 indent 0-->
+<!--page 244 -->
<pre>
Set to 1 or 0 if the currency_symbol respectively precedes or
succeeds the value for a nonnegative locally formatted monetary quantity.</pre>
succeeds the value for a negative internationally formatted monetary
quantity.</pre>
char int_p_sep_by_space
-<!--page 245 indent 4-->
+<!--page 245 -->
<pre>
Set to a value indicating the separation of the int_curr_symbol, the
sign string, and the value for a nonnegative internationally formatted
Set to a value indicating the positioning of the positive_sign for a
nonnegative internationally formatted monetary quantity.</pre>
char int_n_sign_posn
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
Set to a value indicating the positioning of the negative_sign for a
negative internationally formatted monetary quantity.</pre>
<pre>
digits.</pre>
other The integer value is the number of digits that compose the current group.
-<p><!--para 5-->
+<p><!--para 5 -->
<pre>
The next element is examined to determine the size of the next group of
digits before the current group.</pre>
otherwise, a space separates the sign string from the value.</pre>
For int_p_sep_by_space and int_n_sep_by_space, the fourth character of
int_curr_symbol is used instead of a space.
-<p><!--para 6-->
+<p><!--para 6 -->
The values of p_sign_posn, n_sign_posn, int_p_sign_posn, and
int_n_sign_posn are interpreted according to the following:
0 Parentheses surround the quantity and currency symbol.
2 The sign string succeeds the quantity and currency symbol.
3 The sign string immediately precedes the currency symbol.
4 The sign string immediately succeeds the currency symbol.
-<!--page 246 indent 5-->
-<p><!--para 7-->
+<!--page 246 -->
+<p><!--para 7 -->
The implementation shall behave as if no library function calls the localeconv
function.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The localeconv function returns a pointer to the filled-in object. The structure
pointed to by the return value shall not be modified by the program, but may be
overwritten by a subsequent call to the localeconv function. In addition, calls to the
setlocale function with categories LC_ALL, LC_MONETARY, or LC_NUMERIC may
overwrite the contents of the structure.
-<p><!--para 9-->
+<p><!--para 9 -->
EXAMPLE 1 The following table illustrates rules which may well be used by four countries to format
monetary quantities.
<pre>
Country2 L.1.234 -L.1.234 ITL 1.234 -ITL 1.234
Country3 fl. 1.234,56 fl. -1.234,56 NLG 1.234,56 NLG -1.234,56
Country4 SFrs.1,234.56 SFrs.1,234.56C CHF 1,234.56 CHF 1,234.56C
-<p><!--para 10-->
+<p><!--para 10 -->
For these four countries, the respective values for the monetary members of the structure returned by
localeconv could be:
<pre>
int_n_sep_by_space 2 1 2 1
int_p_sign_posn 1 1 1 1
int_n_sign_posn 4 1 4 2
-<!--page 247 indent 5-->
-<p><!--para 11-->
+<!--page 247 -->
+<p><!--para 11 -->
EXAMPLE 2 The following table illustrates how the cs_precedes, sep_by_space, and sign_posn members
affect the formatted value.
<pre>
3 <a href="#1.25">1.25</a>+$ <a href="#1.25">1.25</a> +$ <a href="#1.25">1.25</a>+ $
4 <a href="#1.25">1.25</a>$+ <a href="#1.25">1.25</a> $+ <a href="#1.25">1.25</a>$ +</pre>
-<!--page 248 indent 4-->
+<!--page 248 -->
<pre>
1 0 ($1.25) ($ <a href="#1.25">1.25</a>) ($1.25)
1 +$1.25 +$ <a href="#1.25">1.25</a> + $1.25
4 $+1.25 $+ <a href="#1.25">1.25</a> $ +1.25</pre>
<a name="7.12" href="#7.12"><h3>7.12 Mathematics <math.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.12"><math.h></a> declares two types and many mathematical functions and defines
several macros. Most synopses specify a family of functions consisting of a principal
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.<sup><a href="#note223"><b>223)</b></a></sup>
Integer arithmetic functions and conversion functions are discussed later.
-<p><!--para 2-->
+<p><!--para 2 -->
The types
<pre>
float_t
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.<sup><a href="#note224"><b>224)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The macro
<pre>
HUGE_VAL</pre>
HUGE_VALF
HUGE_VALL</pre>
are respectively float and long double analogs of HUGE_VAL.<sup><a href="#note225"><b>225)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
The macro
<pre>
INFINITY</pre>
-<!--page 249 indent 4-->
+<!--page 249 -->
translation time.<sup><a href="#note226"><b>226)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
The macro
<pre>
NAN</pre>
is defined if and only if the implementation supports quiet NaNs for the float type. It
expands to a constant expression of type float representing a quiet NaN.
-<p><!--para 6-->
+<p><!--para 6 -->
The number classification macros
<pre>
FP_INFINITE
constant expressions with distinct values. Additional implementation-defined floating-
point classifications, with macro definitions beginning with FP_ and an uppercase letter,
may also be specified by the implementation.
-<p><!--para 7-->
+<p><!--para 7 -->
The macro
<pre>
FP_FAST_FMA</pre>
FP_FAST_FMAL</pre>
are, respectively, float and long double analogs of FP_FAST_FMA. If defined,
these macros expand to the integer constant 1.
-<p><!--para 8-->
+<p><!--para 8 -->
The macros
<pre>
FP_ILOGB0
-INT_MAX. The value of FP_ILOGBNAN shall be either INT_MAX or INT_MIN.
-<!--page 250 indent 4-->
-<p><!--para 9-->
+<!--page 250 -->
+<p><!--para 9 -->
The macros
<pre>
MATH_ERRNO
</small>
<a name="7.12.1" href="#7.12.1"><h4>7.12.1 Treatment of error conditions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior of each of the functions in <a href="#7.12"><math.h></a> is specified for all representable
values of its input arguments, except where stated otherwise. Each function shall execute
as if it were a single operation without raising SIGFPE and without generating any of the
floating-point exceptions ''invalid'', ''divide-by-zero'', or ''overflow'' except to reflect
the result of the function.
-<p><!--para 2-->
+<p><!--para 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
expression math_errhandling & MATH_ERRNO is nonzero, the integer expression
errno acquires the value EDOM; if the integer expression math_errhandling &
MATH_ERREXCEPT is nonzero, the ''invalid'' floating-point exception is raised.
-<p><!--para 3-->
+<p><!--para 3 -->
Similarly, a pole error (also known as a singularity or infinitary) occurs if the
mathematical function has an exact infinite result as the finite input argument(s) are
approached in the limit (for example, log(0.0)). The description of each function lists
error, the function returns an implementation-defined value; if the integer expression
-<!--page 251 indent 4-->
+<!--page 251 -->
math_errhandling & MATH_ERRNO is nonzero, the integer expression errno
acquires the value ERANGE; if the integer expression math_errhandling &
MATH_ERREXCEPT is nonzero, the ''divide-by-zero'' floating-point exception is raised.
-<p><!--para 4-->
+<p><!--para 4 -->
Likewise, a range error occurs if the mathematical result of the function cannot be
represented in an object of the specified type, due to extreme magnitude.
-<p><!--para 5-->
+<p><!--para 5 -->
A floating result overflows if the magnitude of the mathematical result is finite but so
large that the mathematical result cannot be represented without extraordinary roundoff
error in an object of the specified type. If a floating result overflows and default rounding
the integer expression errno acquires the value ERANGE; if the integer expression
math_errhandling & MATH_ERREXCEPT is nonzero, the ''overflow'' floating-
point exception is raised.
-<p><!--para 6-->
+<p><!--para 6 -->
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.<sup><a href="#note229"><b>229)</b></a></sup> If the result underflows, the function returns an
value ERANGE is implementation-defined; if the integer expression
math_errhandling & MATH_ERREXCEPT is nonzero, whether the ''underflow''
floating-point exception is raised is implementation-defined.
-<p><!--para 7-->
+<p><!--para 7 -->
If a domain, pole, or range error occurs and the integer expression
math_errhandling & MATH_ERRNO is zero,<sup><a href="#note230"><b>230)</b></a></sup> then errno shall either be set to
the value corresponding to the error or left unmodified. If no such error occurs, errno
-<!--page 252 indent 4-->
+<!--page 252 -->
<h6>footnotes</h6>
<p><small><a name="note228" href="#note228">228)</a> In an implementation that supports infinities, this allows an infinity as an argument to be a domain
<a name="7.12.2" href="#7.12.2"><h4>7.12.2 The FP_CONTRACT pragma</h4></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
#pragma STDC FP_CONTRACT on-off-switch</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The FP_CONTRACT pragma can be used to allow (if the state is ''on'') or disallow (if the
state is ''off'') the implementation to contract expressions (<a href="#6.5">6.5</a>). Each pragma can occur
either outside external declarations or preceding all explicit declarations and statements
implementation-defined.
<a name="7.12.3" href="#7.12.3"><h4>7.12.3 Classification macros</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In the synopses in this subclause, real-floating indicates that the argument shall be an
expression of real floating type.
<a name="7.12.3.1" href="#7.12.3.1"><h5>7.12.3.1 The fpclassify macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int fpclassify(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fpclassify macro classifies its argument value as NaN, infinite, normal,
subnormal, zero, or into another implementation-defined category. First, an argument
represented in a format wider than its semantic type is converted to its semantic type.
Then classification is based on the type of the argument.<sup><a href="#note231"><b>231)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fpclassify macro returns the value of the number classification macro
appropriate to the value of its argument. *
-<!--page 253 indent 4-->
+<!--page 253 -->
<h6>footnotes</h6>
<p><small><a name="note231" href="#note231">231)</a> Since an expression can be evaluated with more range and precision than its type has, it is important to
<a name="7.12.3.2" href="#7.12.3.2"><h5>7.12.3.2 The isfinite macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isfinite(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isfinite macro determines whether its argument has a finite value (zero,
subnormal, or normal, and not infinite or NaN). First, an argument represented in a
format wider than its semantic type is converted to its semantic type. Then determination
is based on the type of the argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isfinite macro returns a nonzero value if and only if its argument has a finite
value.
<a name="7.12.3.3" href="#7.12.3.3"><h5>7.12.3.3 The isinf macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isinf(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isinf macro determines whether its argument value is an infinity (positive or
negative). First, an argument represented in a format wider than its semantic type is
converted to its semantic type. Then determination is based on the type of the argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isinf macro returns a nonzero value if and only if its argument has an infinite
value.
<a name="7.12.3.4" href="#7.12.3.4"><h5>7.12.3.4 The isnan macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isnan(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isnan macro determines whether its argument value is a NaN. First, an argument
represented in a format wider than its semantic type is converted to its semantic type.
Then determination is based on the type of the argument.<sup><a href="#note232"><b>232)</b></a></sup>
-<!--page 254 indent 4-->
+<!--page 254 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isnan macro returns a nonzero value if and only if its argument has a NaN value.
<h6>footnotes</h6>
<a name="7.12.3.5" href="#7.12.3.5"><h5>7.12.3.5 The isnormal macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isnormal(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isnormal macro determines whether its argument value is normal (neither zero,
subnormal, infinite, nor NaN). First, an argument represented in a format wider than its
semantic type is converted to its semantic type. Then determination is based on the type
of the argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isnormal macro returns a nonzero value if and only if its argument has a normal
value.
<a name="7.12.3.6" href="#7.12.3.6"><h5>7.12.3.6 The signbit macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int signbit(real-floating x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The signbit macro determines whether the sign of its argument value is negative.<sup><a href="#note233"><b>233)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The signbit macro returns a nonzero value if and only if the sign of its argument value
is negative.
-<!--page 255 indent 4-->
+<!--page 255 -->
<h6>footnotes</h6>
<p><small><a name="note233" href="#note233">233)</a> The signbit macro reports the sign of all values, including infinities, zeros, and NaNs. If zero is
<a name="7.12.4.1" href="#7.12.4.1"><h5>7.12.4.1 The acos functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double acos(double x);
float acosf(float x);
long double acosl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The acos functions compute the principal value of the arc cosine of x. A domain error
occurs for arguments not in the interval [-1, +1].
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The acos functions return arccos x in the interval [0, pi ] radians.
<a name="7.12.4.2" href="#7.12.4.2"><h5>7.12.4.2 The asin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double asin(double x);
float asinf(float x);
long double asinl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The asin functions compute the principal value of the arc sine of x. A domain error
occurs for arguments not in the interval [-1, +1].
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The asin functions return arcsin x in the interval [-pi /2, +pi /2] radians.
<a name="7.12.4.3" href="#7.12.4.3"><h5>7.12.4.3 The atan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atan(double x);
float atanf(float x);
long double atanl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atan functions compute the principal value of the arc tangent of x.
-<!--page 256 indent 4-->
+<!--page 256 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atan functions return arctan x in the interval [-pi /2, +pi /2] radians.
<a name="7.12.4.4" href="#7.12.4.4"><h5>7.12.4.4 The atan2 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atan2(double y, double x);
float atan2f(float y, float x);
long double atan2l(long double y, long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atan2 functions compute the value of the arc tangent of y/x, using the signs of both
arguments to determine the quadrant of the return value. A domain error may occur if
both arguments are zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atan2 functions return arctan y/x in the interval [-pi , +pi ] radians.
<a name="7.12.4.5" href="#7.12.4.5"><h5>7.12.4.5 The cos functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cos(double x);
float cosf(float x);
long double cosl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cos functions compute the cosine of x (measured in radians).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cos functions return cos x.
<a name="7.12.4.6" href="#7.12.4.6"><h5>7.12.4.6 The sin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sin(double x);
float sinf(float x);
long double sinl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sin functions compute the sine of x (measured in radians).
-<!--page 257 indent 4-->
+<!--page 257 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sin functions return sin x.
<a name="7.12.4.7" href="#7.12.4.7"><h5>7.12.4.7 The tan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tan(double x);
float tanf(float x);
long double tanl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tan functions return the tangent of x (measured in radians).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tan functions return tan x.
<a name="7.12.5" href="#7.12.5"><h4>7.12.5 Hyperbolic functions</h4></a>
<a name="7.12.5.1" href="#7.12.5.1"><h5>7.12.5.1 The acosh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double acosh(double x);
float acoshf(float x);
long double acoshl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain
error occurs for arguments less than 1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The acosh functions return arcosh x in the interval [0, +(inf)].
<a name="7.12.5.2" href="#7.12.5.2"><h5>7.12.5.2 The asinh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double asinh(double x);
float asinhf(float x);
long double asinhl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The asinh functions compute the arc hyperbolic sine of x.
-<!--page 258 indent 4-->
+<!--page 258 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The asinh functions return arsinh x.
<a name="7.12.5.3" href="#7.12.5.3"><h5>7.12.5.3 The atanh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double atanh(double x);
float atanhf(float x);
long double atanhl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atanh functions compute the arc hyperbolic tangent of x. A domain error occurs
for arguments not in the interval [-1, +1]. A pole error may occur if the argument equals
-1 or +1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atanh functions return artanh x.
<a name="7.12.5.4" href="#7.12.5.4"><h5>7.12.5.4 The cosh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cosh(double x);
float coshf(float x);
long double coshl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cosh functions compute the hyperbolic cosine of x. A range error occurs if the
magnitude of x is too large.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cosh functions return cosh x.
<a name="7.12.5.5" href="#7.12.5.5"><h5>7.12.5.5 The sinh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sinh(double x);
float sinhf(float x);
long double sinhl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sinh functions compute the hyperbolic sine of x. A range error occurs if the
magnitude of x is too large.
-<!--page 259 indent 4-->
+<!--page 259 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sinh functions return sinh x.
<a name="7.12.5.6" href="#7.12.5.6"><h5>7.12.5.6 The tanh functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tanh(double x);
float tanhf(float x);
long double tanhl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tanh functions compute the hyperbolic tangent of x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tanh functions return tanh x.
<a name="7.12.6" href="#7.12.6"><h4>7.12.6 Exponential and logarithmic functions</h4></a>
<a name="7.12.6.1" href="#7.12.6.1"><h5>7.12.6.1 The exp functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double exp(double x);
float expf(float x);
long double expl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The exp functions compute the base-e exponential of x. A range error occurs if the
magnitude of x is too large.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The exp functions return ex .
<a name="7.12.6.2" href="#7.12.6.2"><h5>7.12.6.2 The exp2 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double exp2(double x);
float exp2f(float x);
long double exp2l(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The exp2 functions compute the base-2 exponential of x. A range error occurs if the
magnitude of x is too large.
-<!--page 260 indent 4-->
+<!--page 260 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The exp2 functions return 2x .
<a name="7.12.6.3" href="#7.12.6.3"><h5>7.12.6.3 The expm1 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double expm1(double x);
float expm1f(float x);
long double expm1l(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The expm1 functions compute the base-e exponential of the argument, minus 1. A range
error occurs if x is too large.<sup><a href="#note234"><b>234)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The expm1 functions return ex - 1.
<h6>footnotes</h6>
<a name="7.12.6.4" href="#7.12.6.4"><h5>7.12.6.4 The frexp functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double frexp(double value, int *exp);
float frexpf(float value, int *exp);
long double frexpl(long double value, int *exp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The frexp functions break a floating-point number into a normalized fraction and an
integral power of 2. They store the integer in the int object pointed to by exp.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If value is not a floating-point number or if the integral power of 2 is outside the range
of int, the results are unspecified. Otherwise, the frexp functions return the value x,
such that x has a magnitude in the interval [1/2, 1) or zero, and value equals x x 2*exp .
-<!--page 261 indent 4-->
+<!--page 261 -->
<a name="7.12.6.5" href="#7.12.6.5"><h5>7.12.6.5 The ilogb functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int ilogb(double x);
int ilogbf(float x);
int ilogbl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ilogb functions extract the exponent of x as a signed int value. If x is zero they
compute the value FP_ILOGB0; if x is infinite they compute the value INT_MAX; if x is
a NaN they compute the value FP_ILOGBNAN; otherwise, they are equivalent to calling
error or range error may occur if x is zero, infinite, or NaN. If the correct value is outside
the range of the return type, the numeric result is unspecified.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ilogb functions return the exponent of x as a signed int value.
<p><b> Forward references</b>: the logb functions (<a href="#7.12.6.11">7.12.6.11</a>).
<a name="7.12.6.6" href="#7.12.6.6"><h5>7.12.6.6 The ldexp functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double ldexp(double x, int exp);
float ldexpf(float x, int exp);
long double ldexpl(long double x, int exp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ldexp functions multiply a floating-point number by an integral power of 2. A
range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ldexp functions return x x 2exp .
<a name="7.12.6.7" href="#7.12.6.7"><h5>7.12.6.7 The log functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 262 indent 4-->
+<p><!--para 1 -->
+<!--page 262 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log(double x);
float logf(float x);
long double logl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The log functions compute the base-e (natural) logarithm of x. A domain error occurs if
the argument is negative. A pole error may occur if the argument is zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The log functions return loge x.
<a name="7.12.6.8" href="#7.12.6.8"><h5>7.12.6.8 The log10 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log10(double x);
float log10f(float x);
long double log10l(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The log10 functions compute the base-10 (common) logarithm of x. A domain error
occurs if the argument is negative. A pole error may occur if the argument is zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The log10 functions return log10 x.
<a name="7.12.6.9" href="#7.12.6.9"><h5>7.12.6.9 The log1p functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log1p(double x);
float log1pf(float x);
long double log1pl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The log1p functions compute the base-e (natural) logarithm of 1 plus the argument.<sup><a href="#note235"><b>235)</b></a></sup>
A domain error occurs if the argument is less than -1. A pole error may occur if the
argument equals -1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The log1p functions return loge (1 + x).
-<!--page 263 indent 4-->
+<!--page 263 -->
<h6>footnotes</h6>
<p><small><a name="note235" href="#note235">235)</a> For small magnitude x, log1p(x) is expected to be more accurate than log(1 + x).
<a name="7.12.6.10" href="#7.12.6.10"><h5>7.12.6.10 The log2 functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double log2(double x);
float log2f(float x);
long double log2l(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The log2 functions compute the base-2 logarithm of x. A domain error occurs if the
argument is less than zero. A pole error may occur if the argument is zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The log2 functions return log2 x.
<a name="7.12.6.11" href="#7.12.6.11"><h5>7.12.6.11 The logb functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double logb(double x);
float logbf(float x);
long double logbl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The logb functions extract the exponent of x, as a signed integer value in floating-point
format. If x is subnormal it is treated as though it were normalized; thus, for positive
finite x,
1 <= x x FLT_RADIX-logb(x) < FLT_RADIX</pre>
A domain error or pole error may occur if the argument is zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The logb functions return the signed exponent of x.
<a name="7.12.6.12" href="#7.12.6.12"><h5>7.12.6.12 The modf functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double modf(double value, double *iptr);
float modff(float value, float *iptr);
long double modfl(long double value, long double *iptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The modf functions break the argument value into integral and fractional parts, each of
which has the same type and sign as the argument. They store the integral part (in
-<!--page 264 indent 4-->
+<!--page 264 -->
floating-point format) in the object pointed to by iptr.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The modf functions return the signed fractional part of value.
<a name="7.12.6.13" href="#7.12.6.13"><h5>7.12.6.13 The scalbn and scalbln functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double scalbn(double x, int n);
float scalblnf(float x, long int n);
long double scalblnl(long double x, long int n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The scalbn and scalbln functions compute x x FLT_RADIXn efficiently, not
normally by computing FLT_RADIXn explicitly. A range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The scalbn and scalbln functions return x x FLT_RADIXn .
<a name="7.12.7" href="#7.12.7"><h4>7.12.7 Power and absolute-value functions</h4></a>
<a name="7.12.7.1" href="#7.12.7.1"><h5>7.12.7.1 The cbrt functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double cbrt(double x);
float cbrtf(float x);
long double cbrtl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cbrt functions compute the real cube root of x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cbrt functions return x1/3 .
-<!--page 265 indent 4-->
+<!--page 265 -->
<a name="7.12.7.2" href="#7.12.7.2"><h5>7.12.7.2 The fabs functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fabs(double x);
float fabsf(float x);
long double fabsl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fabs functions compute the absolute value of a floating-point number x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fabs functions return | x |.
<a name="7.12.7.3" href="#7.12.7.3"><h5>7.12.7.3 The hypot functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double hypot(double x, double y);
float hypotf(float x, float y);
long double hypotl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The hypot functions compute the square root of the sum of the squares of x and y,
without undue overflow or underflow. A range error may occur.
-<p><!--para 3-->
+<p><!--para 3 -->
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The hypot functions return (sqrt)x2 + y2 .
<pre>
-
<a name="7.12.7.4" href="#7.12.7.4"><h5>7.12.7.4 The pow functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double pow(double x, double y);
float powf(float x, float y);
long double powl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The pow functions compute x raised to the power y. A domain error occurs if x is finite
and negative and y is finite and not an integer value. A range error may occur. A domain
error may occur if x is zero and y is zero. A domain error or pole error may occur if x is
zero and y is less than zero.
-<!--page 266 indent 4-->
+<!--page 266 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The pow functions return xy .
<a name="7.12.7.5" href="#7.12.7.5"><h5>7.12.7.5 The sqrt functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double sqrt(double x);
float sqrtf(float x);
long double sqrtl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sqrt functions compute the nonnegative square root of x. A domain error occurs if
the argument is less than zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sqrt functions return (sqrt)x.
<pre>
-
<a name="7.12.8.1" href="#7.12.8.1"><h5>7.12.8.1 The erf functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double erf(double x);
float erff(float x);
long double erfl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The erf functions compute the error function of x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
2 x
(integral) e-t dt.
<a name="7.12.8.2" href="#7.12.8.2"><h5>7.12.8.2 The erfc functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double erfc(double x);
float erfcf(float x);
long double erfcl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The erfc functions compute the complementary error function of x. A range error
occurs if x is too large.
-<!--page 267 indent 4-->
+<!--page 267 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
2 (inf)
(integral) e-t dt.
<a name="7.12.8.3" href="#7.12.8.3"><h5>7.12.8.3 The lgamma functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double lgamma(double x);
float lgammaf(float x);
long double lgammal(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The lgamma functions compute the natural logarithm of the absolute value of gamma of
x. A range error occurs if x is too large. A pole error may occur if x is a negative integer
or zero.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The lgamma functions return loge | (Gamma)(x) |.
<a name="7.12.8.4" href="#7.12.8.4"><h5>7.12.8.4 The tgamma functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double tgamma(double x);
float tgammaf(float x);
long double tgammal(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tgamma functions compute the gamma function of x. A domain error or pole error
may occur if x is a negative integer or zero. A range error occurs if the magnitude of x is
too large and may occur if the magnitude of x is too small.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tgamma functions return (Gamma)(x).
-<!--page 268 indent 4-->
+<!--page 268 -->
<a name="7.12.9" href="#7.12.9"><h4>7.12.9 Nearest integer functions</h4></a>
<a name="7.12.9.1" href="#7.12.9.1"><h5>7.12.9.1 The ceil functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double ceil(double x);
float ceilf(float x);
long double ceill(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ceil functions compute the smallest integer value not less than x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ceil functions return [^x^], expressed as a floating-point number.
<a name="7.12.9.2" href="#7.12.9.2"><h5>7.12.9.2 The floor functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double floor(double x);
float floorf(float x);
long double floorl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The floor functions compute the largest integer value not greater than x.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The floor functions return [_x_], expressed as a floating-point number.
<a name="7.12.9.3" href="#7.12.9.3"><h5>7.12.9.3 The nearbyint functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nearbyint(double x);
float nearbyintf(float x);
long double nearbyintl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The nearbyint functions round their argument to an integer value in floating-point
format, using the current rounding direction and without raising the ''inexact'' floating-
point exception.
-<!--page 269 indent 4-->
+<!--page 269 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The nearbyint functions return the rounded integer value.
<a name="7.12.9.4" href="#7.12.9.4"><h5>7.12.9.4 The rint functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double rint(double x);
float rintf(float x);
long double rintl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The rint functions differ from the nearbyint functions (<a href="#7.12.9.3">7.12.9.3</a>) only in that the
rint functions may raise the ''inexact'' floating-point exception if the result differs in
value from the argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The rint functions return the rounded integer value.
<a name="7.12.9.5" href="#7.12.9.5"><h5>7.12.9.5 The lrint and llrint functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
long int lrint(double x);
long long int llrintf(float x);
long long int llrintl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The lrint and llrint functions round their argument to the nearest integer value,
rounding according to the current rounding direction. If the rounded value is outside the
range of the return type, the numeric result is unspecified and a domain error or range
error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The lrint and llrint functions return the rounded integer value.
-<!--page 270 indent 4-->
+<!--page 270 -->
<a name="7.12.9.6" href="#7.12.9.6"><h5>7.12.9.6 The round functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double round(double x);
float roundf(float x);
long double roundl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The round functions round their argument to the nearest integer value in floating-point
format, rounding halfway cases away from zero, regardless of the current rounding
direction.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The round functions return the rounded integer value.
<a name="7.12.9.7" href="#7.12.9.7"><h5>7.12.9.7 The lround and llround functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
long int lround(double x);
long long int llroundf(float x);
long long int llroundl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The lround and llround functions round their argument to the nearest integer value,
rounding halfway cases away from zero, regardless of the current rounding direction. If
the rounded value is outside the range of the return type, the numeric result is unspecified
and a domain error or range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The lround and llround functions return the rounded integer value.
<a name="7.12.9.8" href="#7.12.9.8"><h5>7.12.9.8 The trunc functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 271 indent 4-->
+<p><!--para 1 -->
+<!--page 271 -->
<pre>
#include <a href="#7.12"><math.h></a>
double trunc(double x);
float truncf(float x);
long double truncl(long double x);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The trunc functions round their argument to the integer value, in floating format,
nearest to but no larger in magnitude than the argument.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The trunc functions return the truncated integer value.
<a name="7.12.10" href="#7.12.10"><h4>7.12.10 Remainder functions</h4></a>
<a name="7.12.10.1" href="#7.12.10.1"><h5>7.12.10.1 The fmod functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmod(double x, double y);
float fmodf(float x, float y);
long double fmodl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fmod functions compute the floating-point remainder of x/y.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fmod functions return the value x - ny, for some integer n such that, if y is nonzero,
the result has the same sign as x and magnitude less than the magnitude of y. If y is zero,
whether a domain error occurs or the fmod functions return zero is implementation-
<a name="7.12.10.2" href="#7.12.10.2"><h5>7.12.10.2 The remainder functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remainder(double x, double y);
float remainderf(float x, float y);
long double remainderl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The remainder functions compute the remainder x REM y required by IEC 60559.<sup><a href="#note236"><b>236)</b></a></sup>
-<!--page 272 indent 4-->
+<!--page 272 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The remainder functions return x REM y. If y is zero, whether a domain error occurs
or the functions return zero is implementation defined.
<a name="7.12.10.3" href="#7.12.10.3"><h5>7.12.10.3 The remquo functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double remquo(double x, double y, int *quo);
long double remquol(long double x, long double y,
int *quo);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The remquo functions compute the same remainder as the remainder functions. In
the object pointed to by quo they store a value whose sign is the sign of x/y and whose
magnitude is congruent modulo 2n to the magnitude of the integral quotient of x/y, where
n is an implementation-defined integer greater than or equal to 3.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The remquo functions return x REM y. If y is zero, the value stored in the object
pointed to by quo is unspecified and whether a domain error occurs or the functions
return zero is implementation defined.
<a name="7.12.11.1" href="#7.12.11.1"><h5>7.12.11.1 The copysign functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double copysign(double x, double y);
float copysignf(float x, float y);
long double copysignl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The copysign functions produce a value with the magnitude of x and the sign of y.
They produce a NaN (with the sign of y) if x is a NaN. On implementations that
represent a signed zero but do not treat negative zero consistently in arithmetic
operations, the copysign functions regard the sign of zero as positive.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The copysign functions return a value with the magnitude of x and the sign of y.
-<!--page 273 indent 4-->
+<!--page 273 -->
<a name="7.12.11.2" href="#7.12.11.2"><h5>7.12.11.2 The nan functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nan(const char *tagp);
float nanf(const char *tagp);
long double nanl(const char *tagp);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The call nan("n-char-sequence") is equivalent to strtod("NAN(n-char-
sequence)", (char**) NULL); the call nan("") is equivalent to
strtod("NAN()", (char**) NULL). If tagp does not point to an n-char
NULL). Calls to nanf and nanl are equivalent to the corresponding calls to strtof
and strtold.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The nan functions return a quiet NaN, if available, with content indicated through tagp.
If the implementation does not support quiet NaNs, the functions return zero.
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.22.1.3">7.22.1.3</a>).
<a name="7.12.11.3" href="#7.12.11.3"><h5>7.12.11.3 The nextafter functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nextafter(double x, double y);
float nextafterf(float x, float y);
long double nextafterl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The nextafter functions determine the next representable value, in the type of the
function, after x in the direction of y, where x and y are first converted to the type of the
function.<sup><a href="#note237"><b>237)</b></a></sup> The nextafter functions return y if x equals y. A range error may occur
if the magnitude of x is the largest finite value representable in the type and the result is
infinite or not representable in the type.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The nextafter functions return the next representable value in the specified format
after x in the direction of y.
-<!--page 274 indent 4-->
+<!--page 274 -->
<h6>footnotes</h6>
<p><small><a name="note237" href="#note237">237)</a> The argument values are converted to the type of the function, even by a macro implementation of the
<a name="7.12.11.4" href="#7.12.11.4"><h5>7.12.11.4 The nexttoward functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double nexttoward(double x, long double y);
float nexttowardf(float x, long double y);
long double nexttowardl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The nexttoward functions are equivalent to the nextafter functions except that the
second parameter has type long double and the functions return y converted to the
type of the function if x equals y.<sup><a href="#note238"><b>238)</b></a></sup>
<a name="7.12.12.1" href="#7.12.12.1"><h5>7.12.12.1 The fdim functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fdim(double x, double y);
float fdimf(float x, float y);
long double fdiml(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fdim functions determine the positive difference between their arguments:
<pre>
{x - y if x > y
{+0 if x <= y</pre>
A range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fdim functions return the positive difference value.
<a name="7.12.12.2" href="#7.12.12.2"><h5>7.12.12.2 The fmax functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmax(double x, double y);
-<!--page 275 indent 4-->
+<!--page 275 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fmax functions determine the maximum numeric value of their arguments.<sup><a href="#note239"><b>239)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fmax functions return the maximum numeric value of their arguments.
<h6>footnotes</h6>
<a name="7.12.12.3" href="#7.12.12.3"><h5>7.12.12.3 The fmin functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fmin(double x, double y);
float fminf(float x, float y);
long double fminl(long double x, long double y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fmin functions determine the minimum numeric value of their arguments.<sup><a href="#note240"><b>240)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fmin functions return the minimum numeric value of their arguments.
<h6>footnotes</h6>
<a name="7.12.13.1" href="#7.12.13.1"><h5>7.12.13.1 The fma functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
double fma(double x, double y, double z);
long double fmal(long double x, long double y,
long double z);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fma functions compute (x x y) + z, rounded as one ternary operation: they compute
the value (as if) to infinite precision and round once to the result format, according to the
current rounding mode. A range error may occur.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fma functions return (x x y) + z, rounded as one ternary operation.
-<!--page 276 indent 4-->
+<!--page 276 -->
<a name="7.12.14" href="#7.12.14"><h4>7.12.14 Comparison macros</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The relational and equality operators support the usual mathematical relationships
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
<a name="7.12.14.1" href="#7.12.14.1"><h5>7.12.14.1 The isgreater macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isgreater(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isgreater macro determines whether its first argument is greater than its second
argument. The value of isgreater(x, y) is always equal to (x) > (y); however,
unlike (x) > (y), isgreater(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isgreater macro returns the value of (x) > (y).
<a name="7.12.14.2" href="#7.12.14.2"><h5>7.12.14.2 The isgreaterequal macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isgreaterequal(real-floating x, real-floating y);</pre>
-<!--page 277 indent 4-->
+<!--page 277 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isgreaterequal macro determines whether its first argument is greater than or
equal to its second argument. The value of isgreaterequal(x, y) is always equal
to (x) >= (y); however, unlike (x) >= (y), isgreaterequal(x, y) does
not raise the ''invalid'' floating-point exception when x and y are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isgreaterequal macro returns the value of (x) >= (y).
<a name="7.12.14.3" href="#7.12.14.3"><h5>7.12.14.3 The isless macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isless(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isless macro determines whether its first argument is less than its second
argument. The value of isless(x, y) is always equal to (x) < (y); however,
unlike (x) < (y), isless(x, y) does not raise the ''invalid'' floating-point
exception when x and y are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isless macro returns the value of (x) < (y).
<a name="7.12.14.4" href="#7.12.14.4"><h5>7.12.14.4 The islessequal macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int islessequal(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The islessequal macro determines whether its first argument is less than or equal to
its second argument. The value of islessequal(x, y) is always equal to
(x) <= (y); however, unlike (x) <= (y), islessequal(x, y) does not raise
the ''invalid'' floating-point exception when x and y are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The islessequal macro returns the value of (x) <= (y).
-<!--page 278 indent 4-->
+<!--page 278 -->
<a name="7.12.14.5" href="#7.12.14.5"><h5>7.12.14.5 The islessgreater macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int islessgreater(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The islessgreater macro determines whether its first argument is less than or
greater than its second argument. The islessgreater(x, y) macro is similar to
(x) < (y) || (x) > (y); however, islessgreater(x, y) does not raise
the ''invalid'' floating-point exception when x and y are unordered (nor does it evaluate x
and y twice).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The islessgreater macro returns the value of (x) < (y) || (x) > (y).
<a name="7.12.14.6" href="#7.12.14.6"><h5>7.12.14.6 The isunordered macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.12"><math.h></a>
int isunordered(real-floating x, real-floating y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The isunordered macro determines whether its arguments are unordered.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The isunordered macro returns 1 if its arguments are unordered and 0 otherwise.
-<!--page 279 indent 4-->
+<!--page 279 -->
<a name="7.13" href="#7.13"><h3>7.13 Nonlocal jumps <setjmp.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.13"><setjmp.h></a> defines the macro setjmp, and declares one function and
one type, for bypassing the normal function call and return discipline.<sup><a href="#note244"><b>244)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
The type declared is
<pre>
jmp_buf</pre>
invocation of that block, were it called recursively. It does not include the state of the
floating-point status flags, of open files, or of any other component of the abstract
machine.
-<p><!--para 3-->
+<p><!--para 3 -->
It is unspecified whether setjmp is a macro or an identifier declared with external
linkage. If a macro definition is suppressed in order to access an actual function, or a
program defines an external identifier with the name setjmp, the behavior is undefined.
<a name="7.13.1.1" href="#7.13.1.1"><h5>7.13.1.1 The setjmp macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.13"><setjmp.h></a>
int setjmp(jmp_buf env);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The setjmp macro saves its calling environment in its jmp_buf argument for later use
by the longjmp function.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the return is from a direct invocation, the setjmp macro returns the value zero. If the
return is from a call to the longjmp function, the setjmp macro returns a nonzero
value.
Environmental limits
-<p><!--para 4-->
+<p><!--para 4 -->
An invocation of the setjmp macro shall appear only in one of the following contexts:
<ul>
<li> the entire controlling expression of a selection or iteration statement;
constant expression, with the resulting expression being the entire controlling
-<!--page 280 indent 4-->
+<!--page 280 -->
expression of a selection or iteration statement;
<li> the operand of a unary ! operator with the resulting expression being the entire
controlling expression of a selection or iteration statement; or
<li> the entire expression of an expression statement (possibly cast to void).
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
If the invocation appears in any other context, the behavior is undefined.
<a name="7.13.2" href="#7.13.2"><h4>7.13.2 Restore calling environment</h4></a>
<a name="7.13.2.1" href="#7.13.2.1"><h5>7.13.2.1 The longjmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.13"><setjmp.h></a>
_Noreturn void longjmp(jmp_buf env, int val);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The longjmp function restores the environment saved by the most recent invocation of
the setjmp macro in the same invocation of the program with the corresponding
jmp_buf argument. If there has been no such invocation, or if the function containing
the invocation of the setjmp macro has terminated execution<sup><a href="#note245"><b>245)</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.
-<p><!--para 3-->
+<p><!--para 3 -->
All accessible objects have values, and all other components of the abstract machine<sup><a href="#note246"><b>246)</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
and have been changed between the setjmp invocation and longjmp call are
indeterminate.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
After longjmp is completed, program execution continues as if the corresponding
invocation of the setjmp macro had just returned the value specified by val. The
longjmp function cannot cause the setjmp macro to return the value 0; if val is 0,
the setjmp macro returns the value 1.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE The longjmp function that returns control back to the point of the setjmp invocation
might cause memory associated with a variable length array object to be squandered.
-<!--page 281 indent -1-->
-<!--page 282 indent 4-->
+<!--page 281 -->
+<!--page 282 -->
<pre>
#include <a href="#7.13"><setjmp.h></a>
jmp_buf buf;
</small>
<a name="7.14" href="#7.14"><h3>7.14 Signal handling <signal.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.14"><signal.h></a> declares a type and two functions and defines several macros,
for handling various signals (conditions that may be reported during program execution).
-<p><!--para 2-->
+<p><!--para 2 -->
The type defined is
<pre>
sig_atomic_t</pre>
which is the (possibly volatile-qualified) integer type of an object that can be accessed as
an atomic entity, even in the presence of asynchronous interrupts.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros defined are
<pre>
SIG_DFL
compare unequal to the address of any declarable function; and the following, which
expand to positive integer constant expressions with type int and distinct values that are
the signal numbers, each corresponding to the specified condition:
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
SIGABRT abnormal termination, such as is initiated by the abort function
SIGFPE an erroneous arithmetic operation, such as zero divide or an operation
-<!--page 283 indent 4-->
+<!--page 283 -->
<h6>footnotes</h6>
<p><small><a name="note247" href="#note247">247)</a> See ''future library directions'' (<a href="#7.30.6">7.30.6</a>). The names of the signal numbers reflect the following terms
<a name="7.14.1.1" href="#7.14.1.1"><h5>7.14.1.1 The signal function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.14"><signal.h></a>
void (*signal(int sig, void (*func)(int)))(int);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The signal function chooses one of three ways in which receipt of the signal number
sig is to be subsequently handled. If the value of func is SIG_DFL, default handling
for that signal will occur. If the value of func is SIG_IGN, the signal will be ignored.
invocation of such a function because of a signal, or (recursively) of any further functions
called by that invocation (other than functions in the standard library),<sup><a href="#note248"><b>248)</b></a></sup> is called a
signal handler.
-<p><!--para 3-->
+<p><!--para 3 -->
When a signal occurs and func points to a function, it is implementation-defined
whether the equivalent of signal(sig, SIG_DFL); is executed or the
implementation prevents some implementation-defined set of signals (at least including
value of sig is SIGFPE, SIGILL, SIGSEGV, or any other implementation-defined
value corresponding to a computational exception, the behavior is undefined; otherwise
the program will resume execution at the point it was interrupted.
-<p><!--para 4-->
+<p><!--para 4 -->
If the signal occurs as the result of calling the abort or raise function, the signal
handler shall not call the raise function.
-<p><!--para 5-->
+<p><!--para 5 -->
If the signal occurs other than as the result of calling the abort or raise function, the
behavior is undefined if the signal handler refers to any object with static or thread
storage duration that is not a lock-free atomic object other than by assigning a value to an
value of errno is indeterminate.<sup><a href="#note249"><b>249)</b></a></sup>
-<!--page 284 indent 4-->
-<p><!--para 6-->
+<!--page 284 -->
+<p><!--para 6 -->
At program startup, the equivalent of
<pre>
signal(sig, SIG_IGN);</pre>
<pre>
signal(sig, SIG_DFL);</pre>
is executed for all other signals defined by the implementation.
-<p><!--para 7-->
+<p><!--para 7 -->
The implementation shall behave as if no library function calls the signal function.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
If the request can be honored, the signal function returns the value of func for the
most recent successful call to signal for the specified signal sig. Otherwise, a value of
SIG_ERR is returned and a positive value is stored in errno.
<a name="7.14.2.1" href="#7.14.2.1"><h5>7.14.2.1 The raise function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.14"><signal.h></a>
int raise(int sig);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The raise function carries out the actions described in <a href="#7.14.1.1">7.14.1.1</a> for the signal sig. If a
signal handler is called, the raise function shall not return until after the signal handler
does.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The raise function returns zero if successful, nonzero if unsuccessful.
-<!--page 285 indent 4-->
+<!--page 285 -->
<a name="7.15" href="#7.15"><h3>7.15 Alignment <stdalign.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.15"><stdalign.h></a> defines two macros.
-<p><!--para 2-->
+<p><!--para 2 -->
The macro
<pre>
alignas</pre>
expands to _Alignas.
-<p><!--para 3-->
+<p><!--para 3 -->
The remaining macro is suitable for use in #if preprocessing directives. It is
<pre>
__alignas_is_defined</pre>
which expands to the integer constant 1.
-<!--page 286 indent 4-->
+<!--page 286 -->
<a name="7.16" href="#7.16"><h3>7.16 Variable arguments <stdarg.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.16"><stdarg.h></a> declares a type and defines four macros, for advancing
through a list of arguments whose number and types are not known to the called function
when it is translated.
-<p><!--para 2-->
+<p><!--para 2 -->
A function may be called with a variable number of arguments of varying types. As
described in <a href="#6.9.1">6.9.1</a>, its parameter list contains one or more parameters. The rightmost
parameter plays a special role in the access mechanism, and will be designated parmN in
this description.
-<p><!--para 3-->
+<p><!--para 3 -->
The type declared is
<pre>
va_list</pre>
</small>
<a name="7.16.1" href="#7.16.1"><h4>7.16.1 Variable argument list access macros</h4></a>
-<p><!--para 1-->
+<p><!--para 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
identifiers declared with external linkage. If a macro definition is suppressed in order to
<a name="7.16.1.1" href="#7.16.1.1"><h5>7.16.1.1 The va_arg macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
type va_arg(va_list ap, type);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The va_arg macro expands to an expression that has the specified type and the value of
the next argument in the call. The parameter ap shall have been initialized by the
va_start or va_copy macro (without an intervening invocation of the va_end
-<!--page 287 indent 4-->
+<!--page 287 -->
macro for the same ap). Each invocation of the va_arg macro modifies ap so that the
values of successive arguments are returned in turn. The parameter type shall be a type
name specified such that the type of a pointer to an object that has the specified type can
<li> one type is pointer to void and the other is a pointer to a character type.
</ul>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The first invocation of the va_arg macro after that of the va_start macro returns the
value of the argument after that specified by parmN . Successive invocations return the
values of the remaining arguments in succession.
<a name="7.16.1.2" href="#7.16.1.2"><h5>7.16.1.2 The va_copy macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
void va_copy(va_list dest, va_list src);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The va_copy macro initializes dest as a copy of src, as if the va_start macro had
been applied to dest followed by the same sequence of uses of the va_arg macro as
had previously been used to reach the present state of src. Neither the va_copy nor
va_start macro shall be invoked to reinitialize dest without an intervening
invocation of the va_end macro for the same dest.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The va_copy macro returns no value.
<a name="7.16.1.3" href="#7.16.1.3"><h5>7.16.1.3 The va_end macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
void va_end(va_list ap);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The va_end macro facilitates a normal return from the function whose variable
argument list was referred to by the expansion of the va_start macro, or the function
containing the expansion of the va_copy macro, that initialized the va_list ap. The
va_end macro may modify ap so that it is no longer usable (without being reinitialized
-<!--page 288 indent 4-->
+<!--page 288 -->
by the va_start or va_copy macro). If there is no corresponding invocation of the
va_start or va_copy macro, or if the va_end macro is not invoked before the
return, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The va_end macro returns no value.
<a name="7.16.1.4" href="#7.16.1.4"><h5>7.16.1.4 The va_start macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
void va_start(va_list ap, parmN);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The va_start macro shall be invoked before any access to the unnamed arguments.
-<p><!--para 3-->
+<p><!--para 3 -->
The va_start macro initializes ap for subsequent use by the va_arg and va_end
macros. Neither the va_start nor va_copy macro shall be invoked to reinitialize ap
without an intervening invocation of the va_end macro for the same ap.
-<p><!--para 4-->
+<p><!--para 4 -->
The parameter parmN is the identifier of the rightmost parameter in the variable
parameter list in the function definition (the one just before the , ...). If the parameter
parmN is declared with the register storage class, with a function or array type, or
with a type that is not compatible with the type that results after application of the default
argument promotions, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The va_start macro returns no value.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 1 The function f1 gathers into an array a list of arguments that are pointers to strings (but not
more than MAXARGS arguments), then passes the array as a single argument to function f2. The number of
pointers is specified by the first argument to f1.
-<!--page 289 indent 4-->
+<!--page 289 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#define MAXARGS 31
<pre>
void f1(int, ...);</pre>
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 2 The function f3 is similar, but saves the status of the variable argument list after the
indicated number of arguments; after f2 has been called once with the whole list, the trailing part of the list
is gathered again and passed to function f4.
-<!--page 290 indent 4-->
+<!--page 290 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#define MAXARGS 31
<a name="7.17" href="#7.17"><h3>7.17 Atomics <stdatomic.h></h3></a>
<a name="7.17.1" href="#7.17.1"><h4>7.17.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.17"><stdatomic.h></a> defines several macros and declares several types and
functions for performing atomic operations on data shared between threads.
-<p><!--para 2-->
+<p><!--para 2 -->
Implementations that define the macro __STDC_NO_THREADS__ need not provide
this header nor support any of its facilities.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros defined are the atomic lock-free macros
<pre>
ATOMIC_CHAR_LOCK_FREE
<pre>
ATOMIC_FLAG_INIT</pre>
which expands to an initializer for an object of type atomic_flag.
-<p><!--para 4-->
+<p><!--para 4 -->
The types include
<pre>
memory_order</pre>
atomic_address</pre>
which is a structure type representing the atomic analog of a pointer type; and several
atomic analogs of integer types.
-<p><!--para 5-->
+<p><!--para 5 -->
In the following operation definitions:
<ul>
<li> An A refers to one of the atomic types.
-<!--page 291 indent 4-->
+<!--page 291 -->
<li> A C refers to its corresponding non-atomic type. The atomic_address atomic
type corresponds to the void * non-atomic type.
<li> An M refers to the type of the other argument for arithmetic operations. For atomic
corresponding _explicit function with memory_order_seq_cst for the
memory_order argument.
</ul>
-<p><!--para 6-->
+<p><!--para 6 -->
NOTE Many operations are volatile-qualified. The ''volatile as device register'' semantics have not
changed in the standard. This qualification means that volatility is preserved when applying these
operations to volatile objects.
<a name="7.17.2.1" href="#7.17.2.1"><h5>7.17.2.1 The ATOMIC_VAR_INIT macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
#define ATOMIC_VAR_INIT(C value)</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ATOMIC_VAR_INIT macro expands to a token sequence suitable for initializing an
atomic object of a type that is initialization-compatible with value. An atomic object
with automatic storage duration that is not explicitly initialized using
ATOMIC_VAR_INIT is initially in an indeterminate state; however, the default (zero)
initialization for objects with static or thread-local storage duration is guaranteed to
produce a valid state.
-<p><!--para 3-->
+<p><!--para 3 -->
Concurrent access to the variable being initialized, even via an atomic operation,
constitutes a data race.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE
<pre>
atomic_int guide = ATOMIC_VAR_INIT(42);</pre>
<a name="7.17.2.2" href="#7.17.2.2"><h5>7.17.2.2 The atomic_init generic function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
void atomic_init(volatile A *obj, C value);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atomic_init generic function initializes the atomic object pointed to by obj to
the value value, while also initializing any additional state that the implementation
might need to carry for the atomic object.
-<!--page 292 indent 4-->
-<p><!--para 3-->
+<!--page 292 -->
+<p><!--para 3 -->
Although this function initializes an atomic object, it does not avoid data races;
concurrent access to the variable being initialized, even via an atomic operation,
constitutes a data race.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The atomic_init generic function returns no value.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE
<pre>
atomic_int guide;
<a name="7.17.3" href="#7.17.3"><h4>7.17.3 Order and consistency</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The enumerated type memory_order specifies the detailed regular (non-atomic)
memory synchronization operations as defined in <a href="#5.1.2.4">5.1.2.4</a> and may provide for operation
ordering. Its enumeration constants are as follows:
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
memory_order_relaxed
memory_order_consume
memory_order_acq_rel
memory_order_seq_cst</pre>
For memory_order_relaxed, no operation orders memory.
-<p><!--para 3-->
+<p><!--para 3 -->
For memory_order_release, memory_order_acq_rel, and
memory_order_seq_cst, a store operation performs a release operation on the
affected memory location.
-<p><!--para 4-->
+<p><!--para 4 -->
For memory_order_acquire, memory_order_acq_rel, and
memory_order_seq_cst, a load operation performs an acquire operation on the
affected memory location.
-<p><!--para 5-->
+<p><!--para 5 -->
For memory_order_consume, a load operation performs a consume operation on the
affected memory location.
-<p><!--para 6-->
+<p><!--para 6 -->
For memory_order_seq_cst, there shall be a single total order S on all operations,
consistent with the ''happens before'' order and modification orders for all affected
locations, such that each memory_order_seq_cst operation that loads a value
observes either the last preceding modification according to this order S, or the result of
an operation that is not memory_order_seq_cst.
-<p><!--para 7-->
+<p><!--para 7 -->
NOTE 1 Although it is not explicitly required that S include lock operations, it can always be extended to
an order that does include lock and unlock operations, since the ordering between those is already included
in the ''happens before'' ordering.
-<p><!--para 8-->
+<p><!--para 8 -->
NOTE 2 Atomic operations specifying memory_order_relaxed are relaxed only with respect to
memory ordering. Implementations must still guarantee that any given atomic access to a particular atomic
-<!--page 293 indent 5-->
+<!--page 293 -->
object be indivisible with respect to all other atomic accesses to that object.
-<p><!--para 9-->
+<p><!--para 9 -->
For an atomic operation B that reads the value of an atomic object M, if there is a
memory_order_seq_cst fence X sequenced before B, then B observes either the
last memory_order_seq_cst modification of M preceding X in the total order S or
a later modification of M in its modification order.
-<p><!--para 10-->
+<p><!--para 10 -->
For atomic operations A and B on an atomic object M, where A modifies M and B takes
its value, if there is a memory_order_seq_cst fence X such that A is sequenced
before X and B follows X in S, then B observes either the effects of A or a later
modification of M in its modification order.
-<p><!--para 11-->
+<p><!--para 11 -->
For atomic operations A and B on an atomic object M, where A modifies M and B takes
its value, if there are memory_order_seq_cst fences X and Y such that A is
sequenced before X, Y is sequenced before B, and X precedes Y in S, then B observes
either the effects of A or a later modification of M in its modification order.
-<p><!--para 12-->
+<p><!--para 12 -->
Atomic read-modify-write operations shall always read the last value (in the modification
order) stored before the write associated with the read-modify-write operation.
-<p><!--para 13-->
+<p><!--para 13 -->
An atomic store shall only store a value that has been computed from constants and
program input values by a finite sequence of program evaluations, such that each
evaluation observes the values of variables as computed by the last prior assignment in
<li> If an evaluation A is included in the sequence, then all evaluations that assign to the
same variable and happen before A are also included.
</ul>
-<p><!--para 14-->
+<p><!--para 14 -->
NOTE 3 The second requirement disallows ''out-of-thin-air'', or ''speculative'' stores of atomics when
relaxed atomics are used. Since unordered operations are involved, evaluations may appear in this
sequence out of thread order. For example, with x and y initially zero,
-<!--page 294 indent 5-->
+<!--page 294 -->
<pre>
atomic_store_explicit(&y, 42, memory_order_relaxed);
r1 = atomic_load_explicit(&y, memory_order_relaxed);
weaker than memory_order_acq_rel ordering, the second requirement has no impact.
Recommended practice
-<p><!--para 15-->
+<p><!--para 15 -->
The requirements do not forbid r1 == 42 && r2 == 42 in the following example,
with x and y initially zero:
<pre>
if (r2 == 42)
atomic_store_explicit(&x, 42, memory_order_relaxed);</pre>
However, this is not useful behavior, and implementations should not allow it.
-<p><!--para 16-->
+<p><!--para 16 -->
Implementations should make atomic stores visible to atomic loads within a reasonable
amount of time.
<a name="7.17.3.1" href="#7.17.3.1"><h5>7.17.3.1 The kill_dependency macro</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
type kill_dependency(type y);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The kill_dependency macro terminates a dependency chain; the argument does not
carry a dependency to the return value.
-<!--page 295 indent 4-->
+<!--page 295 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The kill_dependency macro returns the value of y.
<a name="7.17.4" href="#7.17.4"><h4>7.17.4 Fences</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This subclause introduces synchronization primitives called fences. Fences can have
acquire semantics, release semantics, or both. A fence with acquire semantics is called
an acquire fence; a fence with release semantics is called a release fence.
-<p><!--para 2-->
+<p><!--para 2 -->
A release fence A synchronizes with an acquire fence B if there exist atomic operations
X and Y , both operating on some atomic object M, such that A is sequenced before X, X
modifies M, Y is sequenced before B, and Y reads the value written by X or a value
written by any side effect in the hypothetical release sequence X would head if it were a
release operation.
-<p><!--para 3-->
+<p><!--para 3 -->
A release fence A synchronizes with an atomic operation B that performs an acquire
operation on an atomic object M if there exists an atomic operation X such that A is
sequenced before X, X modifies M, and B reads the value written by X or a value written
by any side effect in the hypothetical release sequence X would head if it were a release
operation.
-<p><!--para 4-->
+<p><!--para 4 -->
An atomic operation A that is a release operation on an atomic object M synchronizes
with an acquire fence B if there exists some atomic operation X on M such that X is
sequenced before B and reads the value written by A or a value written by any side effect
<a name="7.17.4.1" href="#7.17.4.1"><h5>7.17.4.1 The atomic_thread_fence function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
void atomic_thread_fence(memory_order order);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Depending on the value of order, this operation:
<ul>
<li> has no effects, if order == memory_order_relaxed;
memory_order_acq_rel;
<li> is a sequentially consistent acquire and release fence, if order ==
memory_order_seq_cst.
-<!--page 296 indent 4-->
+<!--page 296 -->
</ul>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atomic_thread_fence function returns no value.
<a name="7.17.4.2" href="#7.17.4.2"><h5>7.17.4.2 The atomic_signal_fence function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
void atomic_signal_fence(memory_order order);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Equivalent to atomic_thread_fence(order), except that ''synchronizes with''
relationships are established only between a thread and a signal handler executed in the
same thread.
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE 1 The atomic_signal_fence function can be used to specify the order in which actions
performed by the thread become visible to the signal handler.
-<p><!--para 4-->
+<p><!--para 4 -->
NOTE 2 Compiler optimizations and reorderings of loads and stores are inhibited in the same way as with
atomic_thread_fence, but the hardware fence instructions that atomic_thread_fence would
have inserted are not emitted.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The atomic_signal_fence function returns no value.
<a name="7.17.5" href="#7.17.5"><h4>7.17.5 Lock-free property</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The atomic lock-free macros indicate the lock-free property of integer and address atomic
types. A value of 0 indicates that the type is never lock-free; a value of 1 indicates that
the type is sometimes lock-free; a value of 2 indicates that the type is always lock-free.
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE Operations that are lock-free should also be address-free. That is, atomic operations on the same
memory location via two different addresses will communicate atomically. The implementation should not
depend on any per-process state. This restriction enables communication via memory mapped into a
<a name="7.17.5.1" href="#7.17.5.1"><h5>7.17.5.1 The atomic_is_lock_free generic function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
_Bool atomic_is_lock_free(atomic_type const volatile *obj);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atomic_is_lock_free generic function indicates whether or not the object
pointed to by obj is lock-free. atomic_type can be any atomic type.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atomic_is_lock_free generic function returns nonzero (true) if and only if the
object's operations are lock-free. The result of a lock-free query on one object cannot be
-<!--page 297 indent 4-->
+<!--page 297 -->
inferred from the result of a lock-free query on another object.
<a name="7.17.6" href="#7.17.6"><h4>7.17.6 Atomic integer and address types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
For each line in the following table, the atomic type name is declared as the
corresponding direct type.
-<!--page 298 indent 4-->
-<p><!--para 2-->
+<!--page 298 -->
+<p><!--para 2 -->
<pre>
Atomic type name Direct type
atomic_char _Atomic char
atomic_intmax_t _Atomic intmax_t
atomic_uintmax_t _Atomic uintmax_t</pre>
The semantics of the operations on these types are defined in <a href="#7.17.7">7.17.7</a>.
-<p><!--para 3-->
+<p><!--para 3 -->
The atomic_bool type provides an atomic boolean.
-<!--page 299 indent 4-->
-<p><!--para 4-->
+<!--page 299 -->
+<p><!--para 4 -->
The atomic_address type provides atomic void * operations. The unit of
addition/subtraction shall be one byte.
-<p><!--para 5-->
+<p><!--para 5 -->
NOTE The representation of atomic integer and address types need not have the same size as their
corresponding regular types. They should have the same size whenever possible, as it eases effort required
to port existing code.
<a name="7.17.7" href="#7.17.7"><h4>7.17.7 Operations on atomic types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
There are only a few kinds of operations on atomic types, though there are many
instances of those kinds. This subclause specifies each general kind.
<a name="7.17.7.1" href="#7.17.7.1"><h5>7.17.7.1 The atomic_store generic functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
void atomic_store(volatile A *object, C desired);
void atomic_store_explicit(volatile A *object,
C desired, memory_order order);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The order argument shall not be memory_order_acquire,
memory_order_consume, nor memory_order_acq_rel. Atomically replace the
value pointed to by object with the value of desired. Memory is affected according
to the value of order.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atomic_store generic functions return no value.
<a name="7.17.7.2" href="#7.17.7.2"><h5>7.17.7.2 The atomic_load generic functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
C atomic_load(volatile A *object);
C atomic_load_explicit(volatile A *object,
memory_order order);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The order argument shall not be memory_order_release nor
memory_order_acq_rel. Memory is affected according to the value of order.
<h6>Returns</h6>
Atomically returns the value pointed to by object.
-<!--page 300 indent 4-->
+<!--page 300 -->
<a name="7.17.7.3" href="#7.17.7.3"><h5>7.17.7.3 The atomic_exchange generic functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
C atomic_exchange(volatile A *object, C desired);
C atomic_exchange_explicit(volatile A *object,
C desired, memory_order order);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Atomically replace the value pointed to by object with desired. Memory is affected
according to the value of order. These operations are read-modify-write operations
(<a href="#5.1.2.4">5.1.2.4</a>).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Atomically returns the value pointed to by object immediately before the effects.
<a name="7.17.7.4" href="#7.17.7.4"><h5>7.17.7.4 The atomic_compare_exchange generic functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
_Bool atomic_compare_exchange_strong(volatile A *object,
volatile A *object, C *expected, C desired,
memory_order success, memory_order failure);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The failure argument shall not be memory_order_release nor
memory_order_acq_rel. The failure argument shall be no stronger than the
success argument. Atomically, compares the value pointed to by object for equality
object. Further, if the comparison is true, memory is affected according to the value of
success, and if the comparison is false, memory is affected according to the value of
failure. These operations are atomic read-modify-write operations (<a href="#5.1.2.4">5.1.2.4</a>).
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE 1 The effect of the compare-and-exchange operations is
-<!--page 301 indent 4-->
+<!--page 301 -->
<pre>
if (*object == *expected)
*object = desired;
else
*expected = *object;</pre>
-<p><!--para 4-->
+<p><!--para 4 -->
The weak compare-and-exchange operations may fail spuriously, that is, return zero
while leaving the value pointed to by expected unchanged.
-<p><!--para 5-->
+<p><!--para 5 -->
NOTE 2 This spurious failure enables implementation of compare-and-exchange on a broader class of
machines, e.g. load-locked store-conditional machines.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE A consequence of spurious failure is that nearly all uses of weak compare-and-exchange will
be in a loop.
<pre>
strong one is preferable.
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The result of the comparison.
<a name="7.17.7.5" href="#7.17.7.5"><h5>7.17.7.5 The atomic_fetch and modify generic functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following operations perform arithmetic and bitwise computations. All of these
operations are applicable to an object of any atomic integer type. Only addition and
subtraction are applicable to atomic_address. None of these operations is applicable
xor ^ bitwise exclusive or
and & bitwise and
<h6>Synopsis</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
C atomic_fetch_key(volatile A *object, M operand);
C atomic_fetch_key_explicit(volatile A *object,
M operand, memory_order order);</pre>
<h6>Description</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Atomically replaces the value pointed to by object with the result of the computation
applied to the value pointed to by object and the given operand. Memory is affected
according to the value of order. These operations are atomic read-modify-write
-<!--page 302 indent 4-->
+<!--page 302 -->
operations (<a href="#5.1.2.4">5.1.2.4</a>). For signed integer types, arithmetic is defined to use two's
complement representation with silent wrap-around on overflow; there are no undefined
results. For address types, the result may be an undefined address, but the operations
otherwise have no undefined behavior.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
Atomically, the value pointed to by object immediately before the effects.
-<p><!--para 5-->
+<p><!--para 5 -->
NOTE The operation of the atomic_fetch and modify generic functions are nearly equivalent to the
operation of the corresponding op= compound assignment operators. The only differences are that the
compound assignment operators are not guaranteed to operate atomically, and the value yielded by a
<a name="7.17.8" href="#7.17.8"><h4>7.17.8 Atomic flag type and operations</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The atomic_flag type provides the classic test-and-set functionality. It has two
states, set and clear.
-<p><!--para 2-->
+<p><!--para 2 -->
Operations on an object of type atomic_flag shall be lock free.
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE Hence the operations should also be address-free. No other type requires lock-free operations, so
the atomic_flag type is the minimum hardware-implemented type needed to conform to this
International standard. The remaining types can be emulated with atomic_flag, though with less than
ideal properties.
-<p><!--para 4-->
+<p><!--para 4 -->
The macro ATOMIC_FLAG_INIT may be used to initialize an atomic_flag to the
clear state. An atomic_flag that is not explicitly initialized with
ATOMIC_FLAG_INIT is initially in an indeterminate state.
-<p><!--para 5-->
+<p><!--para 5 -->
EXAMPLE
<pre>
atomic_flag guard = ATOMIC_FLAG_INIT;</pre>
<a name="7.17.8.1" href="#7.17.8.1"><h5>7.17.8.1 The atomic_flag_test_and_set functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
bool atomic_flag_test_and_set(
bool atomic_flag_test_and_set_explicit(
volatile atomic_flag *object, memory_order order);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Atomically sets the value pointed to by object to true. Memory is affected according
to the value of order. These operations are atomic read-modify-write operations
(<a href="#5.1.2.4">5.1.2.4</a>).
-<!--page 303 indent 4-->
+<!--page 303 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
Atomically, the value of the object immediately before the effects.
<a name="7.17.8.2" href="#7.17.8.2"><h5>7.17.8.2 The atomic_flag_clear functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.17"><stdatomic.h></a>
void atomic_flag_clear(volatile atomic_flag *object);
void atomic_flag_clear_explicit(
volatile atomic_flag *object, memory_order order);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The order argument shall not be memory_order_acquire nor
memory_order_acq_rel. Atomically sets the value pointed to by object to false.
Memory is affected according to the value of order.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atomic_flag_clear functions return no value.
-<!--page 304 indent 4-->
+<!--page 304 -->
<a name="7.18" href="#7.18"><h3>7.18 Boolean type and values <stdbool.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.18"><stdbool.h></a> defines four macros.
-<p><!--para 2-->
+<p><!--para 2 -->
The macro
<pre>
bool</pre>
expands to _Bool.
-<p><!--para 3-->
+<p><!--para 3 -->
The remaining three macros are suitable for use in #if preprocessing directives. They
are
<pre>
<pre>
__bool_true_false_are_defined</pre>
which expands to the integer constant 1.
-<p><!--para 4-->
+<p><!--para 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.<sup><a href="#note252"><b>252)</b></a></sup>
-<!--page 305 indent 4-->
+<!--page 305 -->
<h6>footnotes</h6>
<p><small><a name="note252" href="#note252">252)</a> See ''future library directions'' (<a href="#7.30.7">7.30.7</a>).
</small>
<a name="7.19" href="#7.19"><h3>7.19 Common definitions <stddef.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.19"><stddef.h></a> defines the following macros and declares the following types.
Some are also defined in other headers, as noted in their respective subclauses.
-<p><!--para 2-->
+<p><!--para 2 -->
The types are
<pre>
ptrdiff_t</pre>
shall have a code value equal to its value when used as the lone character in an integer
character constant if an implementation does not define
__STDC_MB_MIGHT_NEQ_WC__.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros are
<pre>
NULL</pre>
then the expression &(t.member-designator) evaluates to an address constant. (If the
specified member is a bit-field, the behavior is undefined.)
Recommended practice
-<p><!--para 4-->
+<p><!--para 4 -->
The types used for size_t and ptrdiff_t should not have an integer conversion rank
greater than that of signed long int unless the implementation supports objects
large enough to make this necessary.
-<!--page 306 indent 0-->
+<!--page 306 -->
<p><b> Forward references</b>: localization (<a href="#7.11">7.11</a>).
-<!--page 307 indent 4-->
+<!--page 307 -->
<a name="7.20" href="#7.20"><h3>7.20 Integer types <stdint.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.20"><stdint.h></a> declares sets of integer types having specified widths, and
defines corresponding sets of macros.<sup><a href="#note253"><b>253)</b></a></sup> It also defines macros that specify limits of
integer types corresponding to types defined in other standard headers.
-<p><!--para 2-->
+<p><!--para 2 -->
Types are defined in the following categories:
<ul>
<li> integer types having certain exact widths;
<li> integer types having greatest width.
</ul>
(Some of these types may denote the same type.)
-<p><!--para 3-->
+<p><!--para 3 -->
Corresponding macros specify limits of the declared types and construct suitable
constants.
-<p><!--para 4-->
+<p><!--para 4 -->
For each type described herein that the implementation provides,<sup><a href="#note254"><b>254)</b></a></sup> <a href="#7.20"><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="#7.20"><stdint.h></a> shall not
</small>
<a name="7.20.1" href="#7.20.1"><h4>7.20.1 Integer types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When typedef names differing only in the absence or presence of the initial u are defined,
they shall denote corresponding signed and unsigned types as described in <a href="#6.2.5">6.2.5</a>; an
implementation providing one of these corresponding types shall also provide the other.
-<p><!--para 2-->
+<p><!--para 2 -->
In the following descriptions, the symbol N represents an unsigned decimal integer with
no leading zeros (e.g., 8 or 24, but not 04 or 048).
-<!--page 308 indent 4-->
+<!--page 308 -->
<a name="7.20.1.1" href="#7.20.1.1"><h5>7.20.1.1 Exact-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The typedef name intN_t designates a signed integer type with width N , no padding
bits, and a two's complement representation. Thus, int8_t denotes such a signed
integer type with a width of exactly 8 bits.
-<p><!--para 2-->
+<p><!--para 2 -->
The typedef name uintN_t designates an unsigned integer type with width N and no
padding bits. Thus, uint24_t denotes such an unsigned integer type with a width of
exactly 24 bits.
-<p><!--para 3-->
+<p><!--para 3 -->
These types are optional. However, if an implementation provides integer types with
widths of 8, 16, 32, or 64 bits, no padding bits, and (for the signed types) that have a
two's complement representation, it shall define the corresponding typedef names.
<a name="7.20.1.2" href="#7.20.1.2"><h5>7.20.1.2 Minimum-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The typedef name int_leastN_t designates a signed integer type with a width of at
least N , such that no signed integer type with lesser size has at least the specified width.
Thus, int_least32_t denotes a signed integer type with a width of at least 32 bits.
-<p><!--para 2-->
+<p><!--para 2 -->
The typedef name uint_leastN_t designates an unsigned integer type with a width
of at least N , such that no unsigned integer type with lesser size has at least the specified
width. Thus, uint_least16_t denotes an unsigned integer type with a width of at
least 16 bits.
-<p><!--para 3-->
+<p><!--para 3 -->
The following types are required:
<pre>
int_least8_t uint_least8_t
All other types of this form are optional.
<a name="7.20.1.3" href="#7.20.1.3"><h5>7.20.1.3 Fastest minimum-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Each of the following types designates an integer type that is usually fastest<sup><a href="#note255"><b>255)</b></a></sup> to operate
with among all integer types that have at least the specified width.
-<p><!--para 2-->
+<p><!--para 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
type with a width of at least N .
-<!--page 309 indent 4-->
-<p><!--para 3-->
+<!--page 309 -->
+<p><!--para 3 -->
The following types are required:
<pre>
int_fast8_t uint_fast8_t
</small>
<a name="7.20.1.4" href="#7.20.1.4"><h5>7.20.1.4 Integer types capable of holding object pointers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following type designates a signed integer type with the property that any valid
pointer to void can be converted to this type, then converted back to pointer to void,
and the result will compare equal to the original pointer:
These types are optional.
<a name="7.20.1.5" href="#7.20.1.5"><h5>7.20.1.5 Greatest-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following type designates a signed integer type capable of representing any value of
any signed integer type:
<pre>
These types are required.
<a name="7.20.2" href="#7.20.2"><h4>7.20.2 Limits of specified-width integer types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following object-like macros specify the minimum and maximum limits of the types *
declared in <a href="#7.20"><stdint.h></a>. Each macro name corresponds to a similar type name in
<a href="#7.20.1">7.20.1</a>.
-<p><!--para 2-->
+<p><!--para 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
the integer 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,
except where stated to be exactly the given value.
-<!--page 310 indent 4-->
+<!--page 310 -->
<a name="7.20.2.1" href="#7.20.2.1"><h5>7.20.2.1 Limits of exact-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum values of exact-width signed integer types
<pre>
</ul>
<a name="7.20.2.2" href="#7.20.2.2"><h5>7.20.2.2 Limits of minimum-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum values of minimum-width signed integer types
<pre>
</ul>
<a name="7.20.2.3" href="#7.20.2.3"><h5>7.20.2.3 Limits of fastest minimum-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum values of fastest minimum-width signed integer types
<pre>
</ul>
<a name="7.20.2.4" href="#7.20.2.4"><h5>7.20.2.4 Limits of integer types capable of holding object pointers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum value of pointer-holding signed integer type
<pre>
INTPTR_MAX 215 - 1
<li> maximum value of pointer-holding unsigned integer type
UINTPTR_MAX 216 - 1
-<!--page 311 indent 4-->
+<!--page 311 -->
</ul>
<a name="7.20.2.5" href="#7.20.2.5"><h5>7.20.2.5 Limits of greatest-width integer types</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> minimum value of greatest-width signed integer type
INTMAX_MIN -(263 - 1)
</ul>
<a name="7.20.3" href="#7.20.3"><h4>7.20.3 Limits of other integer types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following object-like macros specify the minimum and maximum limits of integer *
types corresponding to types defined in other standard headers.
-<p><!--para 2-->
+<p><!--para 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
expression that is an object of the corresponding type converted according to the integer
-<!--page 312 indent 4-->
+<!--page 312 -->
WINT_MIN see below
WINT_MAX see below
</ul>
-<p><!--para 3-->
+<p><!--para 3 -->
If sig_atomic_t (see <a href="#7.14">7.14</a>) is defined as a signed integer type, the value of
SIG_ATOMIC_MIN shall be no greater than -127 and the value of SIG_ATOMIC_MAX
shall be no less than 127; otherwise, sig_atomic_t is defined as an unsigned integer
type, and the value of SIG_ATOMIC_MIN shall be 0 and the value of
SIG_ATOMIC_MAX shall be no less than 255.
-<p><!--para 4-->
+<p><!--para 4 -->
If wchar_t (see <a href="#7.19">7.19</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.<sup><a href="#note257"><b>257)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
If wint_t (see <a href="#7.28">7.28</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
</small>
<a name="7.20.4" href="#7.20.4"><h4>7.20.4 Macros for integer constants</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following function-like macros expand to integer constants suitable for initializing *
objects that have integer types corresponding to types defined in <a href="#7.20"><stdint.h></a>. Each
macro name corresponds to a similar type name in <a href="#7.20.1.2">7.20.1.2</a> or <a href="#7.20.1.5">7.20.1.5</a>.
-<p><!--para 2-->
+<p><!--para 2 -->
The argument in any instance of these macros shall be an unsuffixed integer constant (as
defined in <a href="#6.4.4.1">6.4.4.1</a>) with a value that does not exceed the limits for the corresponding type.
-<p><!--para 3-->
+<p><!--para 3 -->
Each invocation of one of these macros shall expand to an integer constant expression
suitable for use in #if preprocessing directives. The type of the expression shall have
the same type as would an expression of the corresponding type converted according to
the integer promotions. The value of the expression shall be that of the argument.
<a name="7.20.4.1" href="#7.20.4.1"><h5>7.20.4.1 Macros for minimum-width integer constants</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The macro INTN_C(value) shall expand to an integer constant expression
corresponding to the type int_leastN_t. The macro UINTN_C(value) shall expand
to an integer constant expression corresponding to the type uint_leastN_t. For
-<!--page 313 indent 4-->
+<!--page 313 -->
<a name="7.20.4.2" href="#7.20.4.2"><h5>7.20.4.2 Macros for greatest-width integer constants</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following macro expands to an integer constant expression having the value specified
by its argument and the type intmax_t:
<pre>
INTMAX_C(value)</pre>
The following macro expands to an integer constant expression having the value specified
by its argument and the type uintmax_t:
-<!--page 314 indent 4-->
+<!--page 314 -->
<pre>
UINTMAX_C(value)</pre>
<a name="7.21" href="#7.21"><h3>7.21 Input/output <stdio.h></h3></a>
<a name="7.21.1" href="#7.21.1"><h4>7.21.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.21"><stdio.h></a> defines several macros, and declares three types and many
functions for performing input and output.
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are size_t (described in <a href="#7.19">7.19</a>);
<pre>
FILE</pre>
fpos_t</pre>
which is a complete object type other than an array type capable of recording all the
information needed to specify uniquely every position within a file.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros are NULL (described in <a href="#7.19">7.19</a>);
<pre>
_IOFBF
FILENAME_MAX</pre>
which expands to an integer constant expression that is the size needed for an array of
char large enough to hold the longest file name string that the implementation
-<!--page 315 indent 4-->
+<!--page 315 -->
guarantees can be opened;<sup><a href="#note258"><b>258)</b></a></sup>
<pre>
L_tmpnam</pre>
stdout</pre>
which are expressions of type ''pointer to FILE'' that point to the FILE objects
associated, respectively, with the standard error, input, and output streams.
-<p><!--para 4-->
+<p><!--para 4 -->
The header <a href="#7.28"><wchar.h></a> declares a number of functions useful for wide character input
and output. The wide character input/output functions described in that subclause
provide operations analogous to most of those described here, except that the
fundamental units internal to the program are wide characters. The external
representation (in the file) is a sequence of ''generalized'' multibyte characters, as
described further in <a href="#7.21.3">7.21.3</a>.
-<p><!--para 5-->
+<p><!--para 5 -->
The input/output functions are given the following collective terms:
<ul>
<li> The wide character input functions -- those functions described in <a href="#7.28">7.28</a> that perform
putwchar, fwprintf, wprintf, vfwprintf, and vwprintf.
-<!--page 316 indent 4-->
+<!--page 316 -->
<li> The wide character input/output functions -- the union of the ungetwc function, the
wide character input functions, and the wide character output functions.
<li> The byte input/output functions -- those functions described in this subclause that
</small>
<a name="7.21.2" href="#7.21.2"><h4>7.21.2 Streams</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Input and output, whether to or from physical devices such as terminals and tape drives,
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.<sup><a href="#note259"><b>259)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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
immediately preceded by space characters; and the last character is a new-line character.
Whether space characters that are written out immediately before a new-line character
appear when read in is implementation-defined.
-<p><!--para 3-->
+<p><!--para 3 -->
A binary stream is an ordered sequence of characters that can transparently record
internal data. Data read in from a binary stream shall compare equal to the data that were
earlier written out to that stream, under the same implementation. Such a stream may,
however, have an implementation-defined number of null characters appended to the end
of the stream.
-<p><!--para 4-->
+<p><!--para 4 -->
Each stream has an orientation. After a stream is associated with an external file, but
before any operations are performed on it, the stream is without orientation. Once a wide
character input/output function has been applied to a stream without orientation, the
-<!--page 317 indent 4-->
+<!--page 317 -->
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.)<sup><a href="#note260"><b>260)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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,
function can overwrite a partial multibyte character; any file contents beyond the
byte(s) written are henceforth indeterminate.
</ul>
-<p><!--para 6-->
+<p><!--para 6 -->
Each wide-oriented stream has an associated mbstate_t object that stores the current
parse state of the stream. A successful call to fgetpos stores a representation of the
value of this mbstate_t object as part of the value of the fpos_t object. A later
successful call to fsetpos using the same stored fpos_t value restores the value of
the associated mbstate_t object as well as the position within the controlled stream.
Environmental limits
-<p><!--para 7-->
+<p><!--para 7 -->
An implementation shall support text files with lines containing at least 254 characters,
including the terminating new-line character. The value of the macro BUFSIZ shall be at
least 256.
-<!--page 318 indent 4-->
+<!--page 318 -->
<h6>footnotes</h6>
<p><small><a name="note259" href="#note259">259)</a> An implementation need not distinguish between text streams and binary streams. In such an
</small>
<a name="7.21.3" href="#7.21.3"><h4>7.21.3 Files</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A stream is associated with an external file (which may be a physical device) by opening
a file, which may involve creating a new file. Creating an existing file causes its former
contents to be discarded, if necessary. If a file can support positioning requests (such as a
position indicator is initially positioned at the beginning or the end of the file. The file
position indicator is maintained by subsequent reads, writes, and positioning requests, to
facilitate an orderly progression through the file.
-<p><!--para 2-->
+<p><!--para 2 -->
Binary files are not truncated, except as defined in <a href="#7.21.5.3">7.21.5.3</a>. Whether a write on a text
stream causes the associated file to be truncated beyond that point is implementation-
defined.
-<p><!--para 3-->
+<p><!--para 3 -->
When a stream is unbuffered, characters are intended to appear from the source or at the
destination as soon as possible. Otherwise characters may be accumulated and
transmitted to or from the host environment as a block. When a stream is fully buffered,
when input is requested on a line buffered stream that requires the transmission of
characters from the host environment. Support for these characteristics is
implementation-defined, and may be affected via the setbuf and setvbuf functions.
-<p><!--para 4-->
+<p><!--para 4 -->
A file may be disassociated from a controlling stream by closing the file. Output streams
are flushed (any unwritten buffer contents are transmitted to the host environment) before
the stream is disassociated from the file. The value of a pointer to a FILE object is
indeterminate after the associated file is closed (including the standard text streams).
Whether a file of zero length (on which no characters have been written by an output
stream) actually exists is implementation-defined.
-<p><!--para 5-->
+<p><!--para 5 -->
The file may be subsequently reopened, by the same or another program execution, and
its contents reclaimed or modified (if it can be repositioned at its start). If the main
function returns to its original caller, or if the exit function is called, all open files are
closed (hence all output streams are flushed) before program termination. Other paths to
program termination, such as calling the abort function, need not close all files
properly.
-<p><!--para 6-->
+<p><!--para 6 -->
The address of the FILE object used to control a stream may be significant; a copy of a
FILE object need not serve in place of the original.
-<!--page 319 indent 5-->
-<p><!--para 7-->
+<!--page 319 -->
+<p><!--para 7 -->
At program startup, three text streams are predefined and need not be opened explicitly
<ul>
<li> standard input (for reading conventional input), standard output (for writing
opened, the standard error stream is not fully buffered; the standard input and standard
output streams are fully buffered if and only if the stream can be determined not to refer
to an interactive device.
-<p><!--para 8-->
+<p><!--para 8 -->
Functions that open additional (nontemporary) files require a file name, which is a string.
The rules for composing valid file names are implementation-defined. Whether the same
file can be simultaneously open multiple times is also implementation-defined.
-<p><!--para 9-->
+<p><!--para 9 -->
Although both text and binary wide-oriented streams are conceptually sequences of wide
characters, the external file associated with a wide-oriented stream is a sequence of
multibyte characters, generalized as follows:
encodings valid for use internal to the program).
<li> A file need not begin nor end in the initial shift state.<sup><a href="#note261"><b>261)</b></a></sup>
</ul>
-<p><!--para 10-->
+<p><!--para 10 -->
Moreover, the encodings used for multibyte characters may differ among files. Both the
nature and choice of such encodings are implementation-defined.
-<p><!--para 11-->
+<p><!--para 11 -->
The wide character input functions read multibyte characters from the stream and convert
them to wide characters as if they were read by successive calls to the fgetwc function.
Each conversion occurs as if by a call to the mbrtowc function, with the conversion state
described by the stream's own mbstate_t object. The byte input functions read
characters from the stream as if by successive calls to the fgetc function.
-<p><!--para 12-->
+<p><!--para 12 -->
The wide character output functions convert wide characters to multibyte characters and
write them to the stream as if they were written by successive calls to the fputwc
function. Each conversion occurs as if by a call to the wcrtomb function, with the
conversion state described by the stream's own mbstate_t object. The byte output
functions write characters to the stream as if by successive calls to the fputc function.
-<p><!--para 13-->
+<p><!--para 13 -->
In some cases, some of the byte input/output functions also perform conversions between
multibyte characters and wide characters. These conversions also occur as if by calls to
the mbrtowc and wcrtomb functions.
-<p><!--para 14-->
+<p><!--para 14 -->
An encoding error occurs if the character sequence presented to the underlying
mbrtowc function does not form a valid (generalized) multibyte character, or if the code
value passed to the underlying wcrtomb does not correspond to a valid (generalized)
-<!--page 320 indent 5-->
+<!--page 320 -->
multibyte character. The wide character input/output functions and the byte input/output
functions store the value of the macro EILSEQ in errno if and only if an encoding error
occurs.
Environmental limits
-<p><!--para 15-->
+<p><!--para 15 -->
The value of FOPEN_MAX shall be at least eight, including the three standard text
streams.
<p><b> Forward references</b>: the exit function (<a href="#7.22.4.4">7.22.4.4</a>), the fgetc function (<a href="#7.21.7.1">7.21.7.1</a>), the
<a name="7.21.4.1" href="#7.21.4.1"><h5>7.21.4.1 The remove function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int remove(const char *filename);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The remove function causes the file whose name is the string pointed to by filename
to be no longer accessible by that name. A subsequent attempt to open that file using that
name will fail, unless it is created anew. If the file is open, the behavior of the remove
function is implementation-defined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The remove function returns zero if the operation succeeds, nonzero if it fails.
<a name="7.21.4.2" href="#7.21.4.2"><h5>7.21.4.2 The rename function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int rename(const char *old, const char *new);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The rename function causes the file whose name is the string pointed to by old to be
henceforth known by the name given by the string pointed to by new. The file named
old is no longer accessible by that name. If a file named by the string pointed to by new
exists prior to the call to the rename function, the behavior is implementation-defined.
-<!--page 321 indent 4-->
+<!--page 321 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The rename function returns zero if the operation succeeds, nonzero if it fails,<sup><a href="#note262"><b>262)</b></a></sup> in
which case if the file existed previously it is still known by its original name.
<a name="7.21.4.3" href="#7.21.4.3"><h5>7.21.4.3 The tmpfile function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
FILE *tmpfile(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tmpfile function creates a temporary binary file that is different from any other
existing file and that will automatically be removed when it is closed or at program
termination. If the program terminates abnormally, whether an open temporary file is
removed is implementation-defined. The file is opened for update with "wb+" mode.
Recommended practice
-<p><!--para 3-->
+<p><!--para 3 -->
It should be possible to open at least TMP_MAX temporary files during the lifetime of the
program (this limit may be shared with tmpnam) and there should be no limit on the
number simultaneously open other than this limit and any limit on the number of open
files (FOPEN_MAX).
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The tmpfile function returns a pointer to the stream of the file that it created. If the file
cannot be created, the tmpfile function returns a null pointer.
<p><b> Forward references</b>: the fopen function (<a href="#7.21.5.3">7.21.5.3</a>).
<a name="7.21.4.4" href="#7.21.4.4"><h5>7.21.4.4 The tmpnam function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
char *tmpnam(char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tmpnam function generates a string that is a valid file name and that is not the same
as the name of an existing file.<sup><a href="#note263"><b>263)</b></a></sup> The function is potentially capable of generating at
-<!--page 322 indent 4-->
+<!--page 322 -->
least TMP_MAX different strings, but any or all of them may already be in use by existing
files and thus not be suitable return values.
-<p><!--para 3-->
+<p><!--para 3 -->
The tmpnam function generates a different string each time it is called.
-<p><!--para 4-->
+<p><!--para 4 -->
Calls to the tmpnam function with a null pointer argument may introduce data races with
each other. The implementation shall behave as if no library function calls the tmpnam
function.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
If no suitable string can be generated, the tmpnam function returns a null pointer.
Otherwise, if the argument is a null pointer, the tmpnam function leaves its result in an
internal static object and returns a pointer to that object (subsequent calls to the tmpnam
to point to an array of at least L_tmpnam chars; the tmpnam function writes its result
in that array and returns the argument as its value.
Environmental limits
-<p><!--para 6-->
+<p><!--para 6 -->
The value of the macro TMP_MAX shall be at least 25.
<h6>footnotes</h6>
<a name="7.21.5.1" href="#7.21.5.1"><h5>7.21.5.1 The fclose function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fclose(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A successful call to the fclose function causes the stream pointed to by stream to be
flushed and the associated file to be closed. Any unwritten buffered data for the stream
are delivered to the host environment to be written to the file; any unread buffered data
and any buffer set by the setbuf or setvbuf function is disassociated from the stream
(and deallocated if it was automatically allocated).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fclose function returns zero if the stream was successfully closed, or EOF if any
errors were detected.
-<!--page 323 indent 4-->
+<!--page 323 -->
<a name="7.21.5.2" href="#7.21.5.2"><h5>7.21.5.2 The fflush function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fflush(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If stream points to an output stream or an update stream in which the most recent
operation was not input, the fflush function causes any unwritten data for that stream
to be delivered to the host environment to be written to the file; otherwise, the behavior is
undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
If stream is a null pointer, the fflush function performs this flushing action on all
streams for which the behavior is defined above.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The fflush function sets the error indicator for the stream and returns EOF if a write
error occurs, otherwise it returns zero.
<p><b> Forward references</b>: the fopen function (<a href="#7.21.5.3">7.21.5.3</a>).
<a name="7.21.5.3" href="#7.21.5.3"><h5>7.21.5.3 The fopen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
FILE *fopen(const char * restrict filename,
const char * restrict mode);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fopen function opens the file whose name is the string pointed to by filename,
and associates a stream with it.
-<p><!--para 3-->
+<p><!--para 3 -->
The argument mode points to a string. If the string is one of the following, the file is
open in the indicated mode. Otherwise, the behavior is undefined.<sup><a href="#note264"><b>264)</b></a></sup>
r open text file for reading
wb truncate to zero length or create binary file for writing
-<!--page 324 indent 4-->
+<!--page 324 -->
wbx create binary file for writing
ab append; open or create binary file for writing at end-of-file
r+ open text file for update (reading and writing)
w+b or wb+ truncate to zero length or create binary file for update
w+bx or wb+x create binary file for update
a+b or ab+ append; open or create binary file for update, writing at end-of-file
-<p><!--para 4-->
+<p><!--para 4 -->
Opening a file with read mode ('r' as the first character in the mode argument) fails if
the file does not exist or cannot be read.
-<p><!--para 5-->
+<p><!--para 5 -->
Opening a file with exclusive mode ('x' as the last character in the mode argument)
fails if the file already exists or cannot be created. Otherwise, the file is created with
exclusive (also known as non-shared) access to the extent that the underlying system
supports exclusive access.
-<p><!--para 6-->
+<p><!--para 6 -->
Opening a file with append mode ('a' as the first character in the mode argument)
causes all subsequent writes to the file to be forced to the then current end-of-file,
regardless of intervening calls to the fseek function. In some implementations, opening
a binary file with append mode ('b' as the second or third character in the above list of
mode argument values) may initially position the file position indicator for the stream
beyond the last data written, because of null character padding.
-<p><!--para 7-->
+<p><!--para 7 -->
When a file is opened with update mode ('+' as the second or third character in the
above list of mode argument values), both input and output may be performed on the
associated stream. However, output shall not be directly followed by input without an
intervening call to a file positioning function, unless the input operation encounters end-
of-file. Opening (or creating) a text file with update mode may instead open (or create) a
binary stream in some implementations.
-<p><!--para 8-->
+<p><!--para 8 -->
When opened, a stream is fully buffered if and only if it can be determined not to refer to
an interactive device. The error and end-of-file indicators for the stream are cleared.
<h6>Returns</h6>
-<p><!--para 9-->
+<p><!--para 9 -->
The fopen function returns a pointer to the object controlling the stream. If the open
operation fails, fopen returns a null pointer.
<p><b> Forward references</b>: file positioning functions (<a href="#7.21.9">7.21.9</a>).
-<!--page 325 indent 4-->
+<!--page 325 -->
<h6>footnotes</h6>
<p><small><a name="note264" href="#note264">264)</a> If the string begins with one of the above sequences, the implementation might choose to ignore the
<a name="7.21.5.4" href="#7.21.5.4"><h5>7.21.5.4 The freopen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
FILE *freopen(const char * restrict filename,
const char * restrict mode,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The freopen function opens the file whose name is the string pointed to by filename
and associates the stream pointed to by stream with it. The mode argument is used just
as in the fopen function.<sup><a href="#note265"><b>265)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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
permitted (if any), and under what circumstances.
-<p><!--para 4-->
+<p><!--para 4 -->
The freopen function first attempts to close any file that is associated with the specified
stream. Failure to close the file is ignored. The error and end-of-file indicators for the
stream are cleared.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The freopen function returns a null pointer if the open operation fails. Otherwise,
freopen returns the value of stream.
<a name="7.21.5.5" href="#7.21.5.5"><h5>7.21.5.5 The setbuf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
void setbuf(FILE * restrict stream,
char * restrict buf);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
Except that it returns no value, the setbuf function is equivalent to the setvbuf
function invoked with the values _IOFBF for mode and BUFSIZ for size, or (if buf
is a null pointer), with the value _IONBF for mode.
-<!--page 326 indent 4-->
+<!--page 326 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The setbuf function returns no value.
<p><b> Forward references</b>: the setvbuf function (<a href="#7.21.5.6">7.21.5.6</a>).
<a name="7.21.5.6" href="#7.21.5.6"><h5>7.21.5.6 The setvbuf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int setvbuf(FILE * restrict stream,
char * restrict buf,
int mode, size_t size);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The setvbuf function may be used only after the stream pointed to by stream has
been associated with an open file and before any other operation (other than an
unsuccessful call to setvbuf) is performed on the stream. The argument mode
allocated by the setvbuf function. The contents of the array at any time are
indeterminate.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The setvbuf function returns zero on success, or nonzero if an invalid value is given
for mode or if the request cannot be honored.
-<!--page 327 indent 4-->
+<!--page 327 -->
<h6>footnotes</h6>
<p><small><a name="note266" href="#note266">266)</a> The buffer has to have a lifetime at least as great as the open stream, so the stream should be closed
</small>
<a name="7.21.6" href="#7.21.6"><h4>7.21.6 Formatted input/output functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The formatted input/output functions shall behave as if there is a sequence point after the
actions associated with each specifier.<sup><a href="#note267"><b>267)</b></a></sup>
<a name="7.21.6.1" href="#7.21.6.1"><h5>7.21.6.1 The fprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fprintf(FILE * restrict stream,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fprintf function writes output to the stream pointed to by stream, under control
of the string pointed to by format that specifies how subsequent arguments are
converted for output. If there are insufficient arguments for the format, the behavior is
undefined. If the format is exhausted while arguments remain, the excess arguments are
evaluated (as always) but are otherwise ignored. The fprintf function returns when
the end of the format string is encountered.
-<p><!--para 3-->
+<p><!--para 3 -->
The format shall be a multibyte character sequence, beginning and ending in its initial
shift state. The format is composed of zero or more directives: ordinary multibyte
characters (not %), which are copied unchanged to the output stream; and conversion
specifications, each of which results in fetching zero or more subsequent arguments,
converting them, if applicable, according to the corresponding conversion specifier, and
then writing the result to the output stream.
-<p><!--para 4-->
+<p><!--para 4 -->
Each conversion specification is introduced by the character %. After the %, the following
appear in sequence:
<ul>
digits for the g and G conversions, or the maximum number of bytes to be written for
-<!--page 328 indent 4-->
+<!--page 328 -->
s conversions. The precision takes the form of a period (.) followed either by an
asterisk * (described later) or by an optional decimal integer; if only the period is
specified, the precision is taken as zero. If a precision appears with any other
<li> An optional length modifier that specifies the size of the argument.
<li> A conversion specifier character that specifies the type of conversion to be applied.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
As noted above, a field width, or precision, or both, may be indicated by an asterisk. In
this case, an int argument supplies the field width or precision. The arguments
specifying field width, or precision, or both, shall appear (in that order) before the
argument (if any) to be converted. A negative field width argument is taken as a - flag
followed by a positive field width. A negative precision argument is taken as if the
precision were omitted.
-<p><!--para 6-->
+<p><!--para 6 -->
The flag characters and their meanings are:
- The result of the conversion is left-justified within the field. (It is right-justified if
<pre>
0 and - flags both appear, the 0 flag is ignored. For d, i, o, u, x, and X</pre>
-<!--page 329 indent 4-->
-<p><!--para 7-->
+<!--page 329 -->
+<p><!--para 7 -->
<pre>
conversions, if a precision is specified, the 0 flag is ignored. For other
conversions, the behavior is undefined.</pre>
following n conversion specifier applies to a pointer to a signed integer type
corresponding to size_t argument.</pre>
t Specifies that a following d, i, o, u, x, or X conversion specifier applies to a
-<!--page 330 indent 4-->
+<!--page 330 -->
<pre>
ptrdiff_t or the corresponding unsigned integer type argument; or that a
following n conversion specifier applies to a pointer to a ptrdiff_t
applies to a long double argument.</pre>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
-<p><!--para 8-->
+<p><!--para 8 -->
The conversion specifiers and their meanings are:
d,i The int argument is converted to signed decimal in the style [-]dddd. The
<pre>
digits after it is equal to the precision; if the precision is missing, it is taken as</pre>
-<!--page 331 indent 0-->
+<!--page 331 -->
<pre>
6; if the precision is zero and the # flag is not specified, no decimal-point
character appears. The value is rounded to the appropriate number of digits.
-<!--page 332 indent 0-->
+<!--page 332 -->
<pre>
distinguish<sup><a href="#note272"><b>272)</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-
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</pre>
-<!--page 333 indent 5-->
+<!--page 333 -->
<pre>
the precision, the function would need to access a wide character one past the
end of the array. In no case is a partial multibyte character written.<sup><a href="#note274"><b>274)</b></a></sup></pre>
specification includes any flags, a field width, or a precision, the behavior is
undefined.</pre>
% A % character is written. No argument is converted. The complete
-<p><!--para 9-->
+<p><!--para 9 -->
<pre>
conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note275"><b>275)</b></a></sup> If any argument is
not the correct type for the corresponding conversion specification, the behavior is
undefined.
-<p><!--para 10-->
+<p><!--para 10 -->
In no case does a nonexistent or small field width cause truncation of a field; if the result
of a conversion is wider than the field width, the field is expanded to contain the
conversion result.
-<p><!--para 11-->
+<p><!--para 11 -->
For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
to a hexadecimal floating number with the given precision.
Recommended practice
-<p><!--para 12-->
+<p><!--para 12 -->
For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
representable in the given precision, the result should be one of the two adjacent numbers
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.
-<p><!--para 13-->
+<p><!--para 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.<sup><a href="#note276"><b>276)</b></a></sup> If the number of
significant decimal digits is more than DECIMAL_DIG but the source value is exactly
adjacent decimal strings L < U, both having DECIMAL_DIG significant digits; the value
-<!--page 334 indent 5-->
+<!--page 334 -->
of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that
the error should have a correct sign for the current rounding direction.
<h6>Returns</h6>
-<p><!--para 14-->
+<p><!--para 14 -->
The fprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
Environmental limits
-<p><!--para 15-->
+<p><!--para 15 -->
The number of characters that can be produced by any single conversion shall be at least
4095.
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE 1 To print a date and time in the form ''Sunday, July 3, 10:02'' followed by pi to five decimal
places:
<pre>
weekday, month, day, hour, min);
fprintf(stdout, "pi = %.5f\n", 4 * atan(1.0));</pre>
-<p><!--para 17-->
+<p><!--para 17 -->
EXAMPLE 2 In this example, multibyte characters do not have a state-dependent encoding, and the
members of the extended character set that consist of more than one byte each consist of exactly two bytes,
the first of which is denoted here by a and the second by an uppercase letter.
-<p><!--para 18-->
+<p><!--para 18 -->
Given the following wide string with length seven,
<pre>
static wchar_t wstr[] = L" X Yabc Z W";</pre>
| Z|</pre>
<p><b> Forward references</b>: conversion state (<a href="#7.28.6">7.28.6</a>), the wcrtomb function (<a href="#7.28.6.3.3">7.28.6.3.3</a>).
-<!--page 335 indent 4-->
+<!--page 335 -->
<h6>footnotes</h6>
<p><small><a name="note268" href="#note268">268)</a> Note that 0 is taken as a flag, not as the beginning of a field width.
<a name="7.21.6.2" href="#7.21.6.2"><h5>7.21.6.2 The fscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fscanf(FILE * restrict stream,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fscanf function reads input from the stream pointed to by stream, under control
of the string pointed to by format that specifies the admissible input sequences and how
they are to be converted for assignment, using subsequent arguments as pointers to the
objects to receive the converted input. If there are insufficient arguments for the format,
the behavior is undefined. If the format is exhausted while arguments remain, the excess
arguments are evaluated (as always) but are otherwise ignored.
-<p><!--para 3-->
+<p><!--para 3 -->
The format shall be a multibyte character sequence, beginning and ending in its initial
shift state. The format is composed of zero or more directives: one or more white-space
characters, an ordinary multibyte character (neither % nor a white-space character), or a
<li> An optional length modifier that specifies the size of the receiving object.
<li> A conversion specifier character that specifies the type of conversion to be applied.
</ul>
-<p><!--para 4-->
+<p><!--para 4 -->
The fscanf function executes each directive of the format in turn. When all directives
have been executed, or if a directive fails (as detailed below), the function returns.
Failures are described as input failures (due to the occurrence of an encoding error or the
unavailability of input characters), or matching failures (due to inappropriate input).
-<p><!--para 5-->
+<p><!--para 5 -->
A directive composed of white-space character(s) is executed by reading input up to the
first non-white-space character (which remains unread), or until no more characters can
be read.
-<p><!--para 6-->
+<p><!--para 6 -->
A directive that is an ordinary multibyte character is executed by reading the next
characters of the stream. If any of those characters differ from the ones composing the
directive, the directive fails and the differing and subsequent characters remain unread.
Similarly, if end-of-file, an encoding error, or a read error prevents a character from being
read, the directive fails.
-<p><!--para 7-->
+<p><!--para 7 -->
A directive that is a conversion specification defines a set of matching input sequences, as
described below for each specifier. A conversion specification is executed in the
-<!--page 336 indent 5-->
+<!--page 336 -->
following steps:
-<p><!--para 8-->
+<p><!--para 8 -->
Input white-space characters (as specified by the isspace function) are skipped, unless
the specification includes a [, c, or n specifier.<sup><a href="#note277"><b>277)</b></a></sup>
-<p><!--para 9-->
+<p><!--para 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.<sup><a href="#note278"><b>278)</b></a></sup>
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.
-<p><!--para 10-->
+<p><!--para 10 -->
Except in the case of a % specifier, the input item (or, in the case of a %n directive, the
count of input characters) is converted to a type appropriate to the conversion specifier. If
the input item is not a matching sequence, the execution of the directive fails: this
the format argument that has not already received a conversion result. If this object
does not have an appropriate type, or if the result of the conversion cannot be represented
in the object, the behavior is undefined.
-<p><!--para 11-->
+<p><!--para 11 -->
The length modifiers and their meanings are:
hh Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
<pre>
-<!--page 337 indent 5-->
+<!--page 337 -->
j Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
<pre>
to an argument with type pointer to intmax_t or uintmax_t.</pre>
applies to an argument with type pointer to long double.</pre>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
-<p><!--para 12-->
+<p><!--para 12 -->
The conversion specifiers and their meanings are:
d Matches an optionally signed decimal integer, whose format is the same as
<pre>
16 for the base argument. The corresponding argument shall be a pointer to
unsigned integer.</pre>
a,e,f,g Matches an optionally signed floating-point number, infinity, or NaN, whose
-<!--page 338 indent 0-->
+<!--page 338 -->
<pre>
format is the same as expected for the subject sequence of the strtod
function. The corresponding argument shall be a pointer to floating.</pre>
converted to a wide character as if by a call to the mbrtowc function, with
the conversion state described by an mbstate_t object initialized to zero</pre>
-<!--page 339 indent 5-->
+<!--page 339 -->
<pre>
before the first multibyte character is converted. The corresponding argument
shall be a pointer to the initial element of an array of wchar_t large enough
but one is consumed. If the conversion specification includes an assignment-
suppressing character or a field width, the behavior is undefined.</pre>
% Matches a single % character; no conversion or assignment occurs. The
-<p><!--para 13-->
+<p><!--para 13 -->
<pre>
complete conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note280"><b>280)</b></a></sup>
-<p><!--para 14-->
+<p><!--para 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.
-<!--page 340 indent 5-->
-<p><!--para 15-->
+<!--page 340 -->
+<p><!--para 15 -->
Trailing white space (including new-line characters) is left unread unless matched by a
directive. The success of literal matches and suppressed assignments is not directly
determinable other than via the %n directive.
<h6>Returns</h6>
-<p><!--para 16-->
+<p><!--para 16 -->
The fscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the function returns the
number of input items assigned, which can be fewer than provided for, or even zero, in
the event of an early matching failure.
-<p><!--para 17-->
+<p><!--para 17 -->
EXAMPLE 1 The call:
<pre>
#include <a href="#7.21"><stdio.h></a>
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
-<p><!--para 18-->
+<p><!--para 18 -->
EXAMPLE 2 The call:
<pre>
#include <a href="#7.21"><stdio.h></a>
will assign to i the value 56 and to x the value 789.0, will skip 0123, and will assign to name the
sequence 56\0. The next character read from the input stream will be a.
-<p><!--para 19-->
+<p><!--para 19 -->
EXAMPLE 3 To accept repeatedly from stdin a quantity, a unit of measure, and an item name:
-<p><!--para 20-->
+<p><!--para 20 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
/* ... */
fscanf(stdin,"%*[^\n]");
} while (!feof(stdin) && !ferror(stdin));</pre>
If the stdin stream contains the following lines:
-<!--page 341 indent 5-->
+<!--page 341 -->
<pre>
2 quarts of oil
-12.8degrees Celsius
count = 0; // "100e" fails to match "%f"
count = EOF;</pre>
-<p><!--para 21-->
+<p><!--para 21 -->
EXAMPLE 4 In:
<pre>
#include <a href="#7.21"><stdio.h></a>
the value 123 is assigned to d1 and the value 3 to n1. Because %n can never get an input failure the value
of 3 is also assigned to n2. The value of d2 is not affected. The value 1 is assigned to i.
-<p><!--para 22-->
+<p><!--para 22 -->
EXAMPLE 5 In these examples, multibyte characters do have a state-dependent encoding, and the
members of the extended character set that consist of more than one byte each consist of exactly two bytes,
the first of which is denoted here by a and the second by an uppercase letter, but are only recognized as
such when in the alternate shift state. The shift sequences are denoted by (uparrow) and (downarrow), in which the first causes
entry into the alternate shift state.
-<p><!--para 23-->
+<p><!--para 23 -->
After the call:
<pre>
#include <a href="#7.21"><stdio.h></a>
a(uparrow) X Y(downarrow) bc</pre>
str will contain (uparrow) X Y(downarrow)\0 assuming that none of the bytes of the shift sequences (or of the multibyte
characters, in the more general case) appears to be a single-byte white-space character.
-<p><!--para 24-->
+<p><!--para 24 -->
In contrast, after the call:
<pre>
#include <a href="#7.21"><stdio.h></a>
fscanf(stdin, "a%ls", wstr);</pre>
with the same input line, wstr will contain the two wide characters that correspond to X and Y and a
terminating null wide character.
-<p><!--para 25-->
+<p><!--para 25 -->
However, the call:
-<!--page 342 indent 5-->
+<!--page 342 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.19"><stddef.h></a>
fscanf(stdin, "a(uparrow) X(downarrow)%ls", wstr);</pre>
with the same input line will return zero due to a matching failure against the (downarrow) sequence in the format
string.
-<p><!--para 26-->
+<p><!--para 26 -->
Assuming that the first byte of the multibyte character X is the same as the first byte of the multibyte
character Y, after the call:
<pre>
<a name="7.21.6.3" href="#7.21.6.3"><h5>7.21.6.3 The printf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int printf(const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The printf function is equivalent to fprintf with the argument stdout interposed
before the arguments to printf.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The printf function returns the number of characters transmitted, or a negative value if
an output or encoding error occurred.
<a name="7.21.6.4" href="#7.21.6.4"><h5>7.21.6.4 The scanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int scanf(const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The scanf function is equivalent to fscanf with the argument stdin interposed
before the arguments to scanf.
-<!--page 343 indent 4-->
+<!--page 343 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The scanf function returns the value of the macro EOF if an input failure occurs before
the first conversion (if any) has completed. Otherwise, the scanf function returns the
number of input items assigned, which can be fewer than provided for, or even zero, in
<a name="7.21.6.5" href="#7.21.6.5"><h5>7.21.6.5 The snprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int snprintf(char * restrict s, size_t n,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The snprintf function is equivalent to fprintf, except that the output is written into
an array (specified by argument s) rather than to a stream. If n is zero, nothing is written,
and s may be a null pointer. Otherwise, output characters beyond the n-1st are
of the characters actually written into the array. If copying takes place between objects
that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The snprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
value if an encoding error occurred. Thus, the null-terminated output has been
<a name="7.21.6.6" href="#7.21.6.6"><h5>7.21.6.6 The sprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int sprintf(char * restrict s,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sprintf function is equivalent to fprintf, except that the output is written into
an array (specified by the argument s) rather than to a stream. A null character is written
at the end of the characters written; it is not counted as part of the returned value. If
copying takes place between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sprintf function returns the number of characters written in the array, not
counting the terminating null character, or a negative value if an encoding error occurred.
-<!--page 344 indent 4-->
+<!--page 344 -->
<a name="7.21.6.7" href="#7.21.6.7"><h5>7.21.6.7 The sscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int sscanf(const char * restrict s,
const char * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The sscanf function is equivalent to fscanf, except that input is obtained from a
string (specified by the argument s) rather than from a stream. Reaching the end of the
string is equivalent to encountering end-of-file for the fscanf function. If copying
takes place between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The sscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the sscanf function
returns the number of input items assigned, which can be fewer than provided for, or even
<a name="7.21.6.8" href="#7.21.6.8"><h5>7.21.6.8 The vfprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vfprintf function is equivalent to fprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfprintf function does not invoke the
va_end macro.<sup><a href="#note281"><b>281)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vfprintf function returns the number of characters transmitted, or a negative
value if an output or encoding error occurred.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The following shows the use of the vfprintf function in a general error-reporting routine.
-<!--page 345 indent 4-->
+<!--page 345 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
<a name="7.21.6.9" href="#7.21.6.9"><h5>7.21.6.9 The vfscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vfscanf function is equivalent to fscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfscanf function does not invoke the
va_end macro.281)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vfscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the vfscanf function
returns the number of input items assigned, which can be fewer than provided for, or even
<a name="7.21.6.10" href="#7.21.6.10"><h5>7.21.6.10 The vprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
int vprintf(const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vprintf function is equivalent to printf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
-<!--page 346 indent 4-->
+<!--page 346 -->
possibly subsequent va_arg calls). The vprintf function does not invoke the
va_end macro.281)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vprintf function returns the number of characters transmitted, or a negative value
if an output or encoding error occurred.
<a name="7.21.6.11" href="#7.21.6.11"><h5>7.21.6.11 The vscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
int vscanf(const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vscanf function is equivalent to scanf, with the variable argument list replaced
by arg, which shall have been initialized by the va_start macro (and possibly
subsequent va_arg calls). The vscanf function does not invoke the va_end
macro.281)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the vscanf function
returns the number of input items assigned, which can be fewer than provided for, or even
<a name="7.21.6.12" href="#7.21.6.12"><h5>7.21.6.12 The vsnprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vsnprintf function is equivalent to snprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsnprintf function does not invoke the
va_end macro.281) If copying takes place between objects that overlap, the behavior is
undefined.
-<!--page 347 indent 4-->
+<!--page 347 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vsnprintf function returns the number of characters that would have been written
had n been sufficiently large, not counting the terminating null character, or a negative
value if an encoding error occurred. Thus, the null-terminated output has been
<a name="7.21.6.13" href="#7.21.6.13"><h5>7.21.6.13 The vsprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vsprintf function is equivalent to sprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsprintf function does not invoke the
va_end macro.281) If copying takes place between objects that overlap, the behavior is
undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vsprintf function returns the number of characters written in the array, not
counting the terminating null character, or a negative value if an encoding error occurred.
<a name="7.21.6.14" href="#7.21.6.14"><h5>7.21.6.14 The vsscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
const char * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vsscanf function is equivalent to sscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsscanf function does not invoke the
va_end macro.281)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vsscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the vsscanf function
-<!--page 348 indent 4-->
+<!--page 348 -->
returns the number of input items assigned, which can be fewer than provided for, or even
zero, in the event of an early matching failure.
<a name="7.21.7.1" href="#7.21.7.1"><h5>7.21.7.1 The fgetc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fgetc(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next character is present, the fgetc function obtains that character as an unsigned
char converted to an int and advances the associated file position indicator for the
stream (if defined).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetc function returns EOF. Otherwise, the
fgetc function returns the next character from the input stream pointed to by stream.
<a name="7.21.7.2" href="#7.21.7.2"><h5>7.21.7.2 The fgets function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
char *fgets(char * restrict s, int n,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fgets function reads at most one less than the number of characters specified by n
from the stream pointed to by stream into the array pointed to by s. No additional
characters are read after a new-line character (which is retained) or after end-of-file. A
null character is written immediately after the last character read into the array.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fgets function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
null pointer is returned. If a read error occurs during the operation, the array contents are
indeterminate and a null pointer is returned.
-<!--page 349 indent 4-->
+<!--page 349 -->
<a name="7.21.7.3" href="#7.21.7.3"><h5>7.21.7.3 The fputc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fputc(int c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fputc function writes the character specified by c (converted to an unsigned
char) to the output stream pointed to by stream, at the position indicated by the
associated file position indicator for the stream (if defined), and advances the indicator
appropriately. If the file cannot support positioning requests, or if the stream was opened
with append mode, the character is appended to the output stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fputc function returns the character written. If a write error occurs, the error
indicator for the stream is set and fputc returns EOF.
<a name="7.21.7.4" href="#7.21.7.4"><h5>7.21.7.4 The fputs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fputs(const char * restrict s,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fputs function writes the string pointed to by s to the stream pointed to by
stream. The terminating null character is not written.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fputs function returns EOF if a write error occurs; otherwise it returns a
nonnegative value.
<a name="7.21.7.5" href="#7.21.7.5"><h5>7.21.7.5 The getc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int getc(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getc function is equivalent to fgetc, except that if it is implemented as a macro, it
may evaluate stream more than once, so the argument should never be an expression
with side effects.
-<!--page 350 indent 4-->
+<!--page 350 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The getc function returns the next character from the input stream pointed to by
stream. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
getc returns EOF. If a read error occurs, the error indicator for the stream is set and
<a name="7.21.7.6" href="#7.21.7.6"><h5>7.21.7.6 The getchar function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int getchar(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getchar function is equivalent to getc with the argument stdin.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The getchar function returns the next character from the input stream pointed to by
stdin. If the stream is at end-of-file, the end-of-file indicator for the stream is set and
getchar returns EOF. If a read error occurs, the error indicator for the stream is set and
<a name="7.21.7.7" href="#7.21.7.7"><h5>7.21.7.7 The putc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int putc(int c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The putc function is equivalent to fputc, except that if it is implemented as a macro, it
may evaluate stream more than once, so that argument should never be an expression
with side effects.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The putc function returns the character written. If a write error occurs, the error
indicator for the stream is set and putc returns EOF.
<a name="7.21.7.8" href="#7.21.7.8"><h5>7.21.7.8 The putchar function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int putchar(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The putchar function is equivalent to putc with the second argument stdout.
-<!--page 351 indent 4-->
+<!--page 351 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The putchar function returns the character written. If a write error occurs, the error
indicator for the stream is set and putchar returns EOF.
<a name="7.21.7.9" href="#7.21.7.9"><h5>7.21.7.9 The puts function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int puts(const char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The puts function writes the string pointed to by s to the stream pointed to by stdout,
and appends a new-line character to the output. The terminating null character is not
written.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The puts function returns EOF if a write error occurs; otherwise it returns a nonnegative
value.
<a name="7.21.7.10" href="#7.21.7.10"><h5>7.21.7.10 The ungetc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int ungetc(int c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ungetc function pushes the character specified by c (converted to an unsigned
char) back onto the input stream pointed to by stream. Pushed-back characters will be
returned by subsequent reads on that stream in the reverse order of their pushing. A
successful intervening call (with the stream pointed to by stream) to a file positioning
function (fseek, fsetpos, or rewind) discards any pushed-back characters for the
stream. The external storage corresponding to the stream is unchanged.
-<p><!--para 3-->
+<p><!--para 3 -->
One character of pushback is guaranteed. If the ungetc function is called too many
times on the same stream without an intervening read or file positioning operation on that
stream, the operation may fail.
-<p><!--para 4-->
+<p><!--para 4 -->
If the value of c equals that of the macro EOF, the operation fails and the input stream is
unchanged.
-<p><!--para 5-->
+<p><!--para 5 -->
A successful call to the ungetc function clears the end-of-file indicator for the stream.
The value of the file position indicator for the stream after reading or discarding all
pushed-back characters shall be the same as it was before the characters were pushed
back. For a text stream, the value of its file position indicator after a successful call to the
ungetc function is unspecified until all pushed-back characters are read or discarded.
-<!--page 352 indent 4-->
+<!--page 352 -->
For a binary stream, its file position indicator is decremented by each successful call to
the ungetc function; if its value was zero before a call, it is indeterminate after the
call.<sup><a href="#note283"><b>283)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The ungetc function returns the character pushed back after conversion, or EOF if the
operation fails.
<p><b> Forward references</b>: file positioning functions (<a href="#7.21.9">7.21.9</a>).
<a name="7.21.8.1" href="#7.21.8.1"><h5>7.21.8.1 The fread function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
size_t fread(void * restrict ptr,
size_t size, size_t nmemb,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fread function reads, into the array pointed to by ptr, up to nmemb elements
whose size is specified by size, from the stream pointed to by stream. For each
object, size calls are made to the fgetc function and the results stored, in the order
read. If an error occurs, the resulting value of the file position indicator for the stream is
indeterminate. If a partial element is read, its value is indeterminate.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fread function returns the number of elements successfully read, which may be
less than nmemb if a read error or end-of-file is encountered. If size or nmemb is zero,
fread returns zero and the contents of the array and the state of the stream remain
-<!--page 353 indent 4-->
+<!--page 353 -->
<a name="7.21.8.2" href="#7.21.8.2"><h5>7.21.8.2 The fwrite function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
size_t fwrite(const void * restrict ptr,
size_t size, size_t nmemb,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fwrite function writes, from the array pointed to by ptr, up to nmemb elements
whose size is specified by size, to the stream pointed to by stream. For each object,
size calls are made to the fputc function, taking the values (in order) from an array of
error occurs, the resulting value of the file position indicator for the stream is
indeterminate.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fwrite function returns the number of elements successfully written, which will be
less than nmemb only if a write error is encountered. If size or nmemb is zero,
fwrite returns zero and the state of the stream remains unchanged.
<a name="7.21.9.1" href="#7.21.9.1"><h5>7.21.9.1 The fgetpos function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fgetpos(FILE * restrict stream,
fpos_t * restrict pos);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fgetpos function stores the current values of the parse state (if any) and file
position indicator for the stream pointed to by stream in the object pointed to by pos.
The values stored contain unspecified information usable by the fsetpos function for
repositioning the stream to its position at the time of the call to the fgetpos function.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If successful, the fgetpos function returns zero; on failure, the fgetpos function
returns nonzero and stores an implementation-defined positive value in errno.
<p><b> Forward references</b>: the fsetpos function (<a href="#7.21.9.3">7.21.9.3</a>).
-<!--page 354 indent 4-->
+<!--page 354 -->
<a name="7.21.9.2" href="#7.21.9.2"><h5>7.21.9.2 The fseek function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fseek(FILE *stream, long int offset, int whence);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fseek function sets the file position indicator for the stream pointed to by stream.
If a read or write error occurs, the error indicator for the stream is set and fseek fails.
-<p><!--para 3-->
+<p><!--para 3 -->
For a binary stream, the new position, measured in characters from the beginning of the
file, is obtained by adding offset to the position specified by whence. The specified
position is the beginning of the file if whence is SEEK_SET, the current value of the file
position indicator if SEEK_CUR, or end-of-file if SEEK_END. A binary stream need not
meaningfully support fseek calls with a whence value of SEEK_END.
-<p><!--para 4-->
+<p><!--para 4 -->
For a text stream, either offset shall be zero, or offset shall be a value returned by
an earlier successful call to the ftell function on a stream associated with the same file
and whence shall be SEEK_SET.
-<p><!--para 5-->
+<p><!--para 5 -->
After determining the new position, a successful call to the fseek function undoes any
effects of the ungetc function on the stream, clears the end-of-file indicator for the
stream, and then establishes the new position. After a successful fseek call, the next
operation on an update stream may be either input or output.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The fseek function returns nonzero only for a request that cannot be satisfied.
<p><b> Forward references</b>: the ftell function (<a href="#7.21.9.4">7.21.9.4</a>).
<a name="7.21.9.3" href="#7.21.9.3"><h5>7.21.9.3 The fsetpos function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int fsetpos(FILE *stream, const fpos_t *pos);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fsetpos function sets the mbstate_t object (if any) and file position indicator
for the stream pointed to by stream according to the value of the object pointed to by
pos, which shall be a value obtained from an earlier successful call to the fgetpos
function on a stream associated with the same file. If a read or write error occurs, the
error indicator for the stream is set and fsetpos fails.
-<p><!--para 3-->
+<p><!--para 3 -->
A successful call to the fsetpos function undoes any effects of the ungetc function
on the stream, clears the end-of-file indicator for the stream, and then establishes the new
parse state and position. After a successful fsetpos call, the next operation on an
-<!--page 355 indent 4-->
+<!--page 355 -->
update stream may be either input or output.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If successful, the fsetpos function returns zero; on failure, the fsetpos function
returns nonzero and stores an implementation-defined positive value in errno.
<a name="7.21.9.4" href="#7.21.9.4"><h5>7.21.9.4 The ftell function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
long int ftell(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ftell function obtains the current value of the file position indicator for the stream
pointed to by stream. For a binary stream, the value is the number of characters from
the beginning of the file. For a text stream, its file position indicator contains unspecified
return values is not necessarily a meaningful measure of the number of characters written
or read.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If successful, the ftell function returns the current value of the file position indicator
for the stream. On failure, the ftell function returns -1L and stores an
implementation-defined positive value in errno.
<a name="7.21.9.5" href="#7.21.9.5"><h5>7.21.9.5 The rewind function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
void rewind(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The rewind function sets the file position indicator for the stream pointed to by
stream to the beginning of the file. It is equivalent to
<pre>
(void)fseek(stream, 0L, SEEK_SET)</pre>
except that the error indicator for the stream is also cleared.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The rewind function returns no value.
-<!--page 356 indent 4-->
+<!--page 356 -->
<a name="7.21.10" href="#7.21.10"><h4>7.21.10 Error-handling functions</h4></a>
<a name="7.21.10.1" href="#7.21.10.1"><h5>7.21.10.1 The clearerr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
void clearerr(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The clearerr function clears the end-of-file and error indicators for the stream pointed
to by stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The clearerr function returns no value.
<a name="7.21.10.2" href="#7.21.10.2"><h5>7.21.10.2 The feof function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int feof(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The feof function tests the end-of-file indicator for the stream pointed to by stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The feof function returns nonzero if and only if the end-of-file indicator is set for
stream.
<a name="7.21.10.3" href="#7.21.10.3"><h5>7.21.10.3 The ferror function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
int ferror(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ferror function tests the error indicator for the stream pointed to by stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ferror function returns nonzero if and only if the error indicator is set for
stream.
-<!--page 357 indent 4-->
+<!--page 357 -->
<a name="7.21.10.4" href="#7.21.10.4"><h5>7.21.10.4 The perror function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
void perror(const char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The perror function maps the error number in the integer expression errno to an
error message. It writes a sequence of characters to the standard error stream thus: first
(if s is not a null pointer and the character pointed to by s is not the null character), the
message string followed by a new-line character. The contents of the error message
strings are the same as those returned by the strerror function with argument errno.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The perror function returns no value.
<p><b> Forward references</b>: the strerror function (<a href="#7.23.6.2">7.23.6.2</a>).
-<!--page 358 indent 4-->
+<!--page 358 -->
<a name="7.22" href="#7.22"><h3>7.22 General utilities <stdlib.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.22"><stdlib.h></a> declares five types and several functions of general utility, and
defines several macros.<sup><a href="#note284"><b>284)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are size_t and wchar_t (both described in <a href="#7.19">7.19</a>),
<pre>
div_t</pre>
<pre>
lldiv_t</pre>
which is a structure type that is the type of the value returned by the lldiv function.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.19">7.19</a>);
<pre>
EXIT_FAILURE</pre>
-<!--page 359 indent 4-->
+<!--page 359 -->
<h6>footnotes</h6>
<p><small><a name="note284" href="#note284">284)</a> See ''future library directions'' (<a href="#7.30.10">7.30.10</a>).
</small>
<a name="7.22.1" href="#7.22.1"><h4>7.22.1 Numeric conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions atof, atoi, atol, and atoll need not affect the value of the integer
expression errno on an error. If the value of the result cannot be represented, the
behavior is undefined.
<a name="7.22.1.1" href="#7.22.1.1"><h5>7.22.1.1 The atof function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
double atof(const char *nptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atof function converts the initial portion of the string pointed to by nptr to
double representation. Except for the behavior on error, it is equivalent to
<pre>
strtod(nptr, (char **)NULL)</pre>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atof function returns the converted value.
<p><b> Forward references</b>: the strtod, strtof, and strtold functions (<a href="#7.22.1.3">7.22.1.3</a>).
<a name="7.22.1.2" href="#7.22.1.2"><h5>7.22.1.2 The atoi, atol, and atoll functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int atoi(const char *nptr);
long int atol(const char *nptr);
long long int atoll(const char *nptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atoi, atol, and atoll functions convert the initial portion of the string pointed
to by nptr to int, long int, and long long int representation, respectively.
Except for the behavior on error, they are equivalent to
atol: strtol(nptr, (char **)NULL, 10)
atoll: strtoll(nptr, (char **)NULL, 10)</pre>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The atoi, atol, and atoll functions return the converted value.
<p><b> Forward references</b>: the strtol, strtoll, strtoul, and strtoull functions
(<a href="#7.22.1.4">7.22.1.4</a>).
-<!--page 360 indent 4-->
+<!--page 360 -->
<a name="7.22.1.3" href="#7.22.1.3"><h5>7.22.1.3 The strtod, strtof, and strtold functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
double strtod(const char * restrict nptr,
long double strtold(const char * restrict nptr,
char ** restrict endptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strtod, strtof, and strtold functions convert the initial portion of the string
pointed to by nptr to double, float, and long double representation,
respectively. First, they decompose the input string into three parts: an initial, possibly
and a final string of one or more unrecognized characters, including the terminating null
character of the input string. Then, they attempt to convert the subject sequence to a
floating-point number, and return the result.
-<p><!--para 3-->
+<p><!--para 3 -->
The expected form of the subject sequence is an optional plus or minus sign, then one of
the following:
<ul>
The subject sequence is defined as the longest initial subsequence of the input string,
starting with the first non-white-space character, that is of the expected form. The subject
sequence contains no characters if the input string is not of the expected form.
-<p><!--para 4-->
+<p><!--para 4 -->
If the subject sequence has the expected form for a floating-point number, the sequence of
characters starting with the first digit or the decimal-point character (whichever occurs
first) is interpreted as a floating constant according to the rules of <a href="#6.4.4.2">6.4.4.2</a>, except that the
-<!--page 361 indent 4-->
+<!--page 361 -->
decimal-point character is used in place of a period, and that if neither an exponent part
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
the expected form; the meaning of the n-char sequences is implementation-defined.<sup><a href="#note286"><b>286)</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.
-<p><!--para 5-->
+<p><!--para 5 -->
If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the
value resulting from the conversion is correctly rounded.
-<p><!--para 6-->
+<p><!--para 6 -->
In other than the "C" locale, additional locale-specific subject sequence forms may be
accepted.
-<p><!--para 7-->
+<p><!--para 7 -->
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
Recommended practice
-<p><!--para 8-->
+<p><!--para 8 -->
If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
the result is not exactly representable, the result should be one of the two numbers in the
appropriate internal format that are adjacent to the hexadecimal floating source value,
with the extra stipulation that the error should have a correct sign for the current rounding
direction.
-<p><!--para 9-->
+<p><!--para 9 -->
If the subject sequence has the decimal form and at most DECIMAL_DIG (defined in
<a href="#7.7"><float.h></a>) significant digits, the result should be correctly rounded. If the subject
sequence D has the decimal form and more than DECIMAL_DIG significant digits,
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
-<!--page 362 indent 5-->
+<!--page 362 -->
stipulation that the error with respect to D should have a correct sign for the current
rounding direction.<sup><a href="#note287"><b>287)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
The functions return the converted value, if any. If no conversion could be performed,
zero is returned. If the correct value overflows and default rounding is in effect (<a href="#7.12.1">7.12.1</a>),
plus or minus HUGE_VAL, HUGE_VALF, or HUGE_VALL is returned (according to the
<a name="7.22.1.4" href="#7.22.1.4"><h5>7.22.1.4 The strtol, strtoll, strtoul, and strtoull functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
long int strtol(
char ** restrict endptr,
int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strtol, strtoll, strtoul, and strtoull functions convert the initial
portion of the string pointed to by nptr to long int, long long int, unsigned
long int, and unsigned long long int representation, respectively. First,
white-space characters (as specified by the isspace function), a subject sequence
-<!--page 363 indent 4-->
+<!--page 363 -->
resembling an integer represented in some radix determined by the value of base, and a
final string of one or more unrecognized characters, including the terminating null
character of the input string. Then, they attempt to convert the subject sequence to an
integer, and return the result.
-<p><!--para 3-->
+<p><!--para 3 -->
If the value of base is zero, the expected form of the subject sequence is that of an
integer constant as described in <a href="#6.4.4.1">6.4.4.1</a>, optionally preceded by a plus or minus sign, but
not including an integer suffix. If the value of base is between 2 and 36 (inclusive), the
ascribed the values 10 through 35; only letters and digits whose ascribed values are less
than that of base are permitted. If the value of base is 16, the characters 0x or 0X may
optionally precede the sequence of letters and digits, following the sign if present.
-<p><!--para 4-->
+<p><!--para 4 -->
The subject sequence is defined as the longest initial subsequence of the input string,
starting with the first non-white-space character, that is of the expected form. The subject
sequence contains no characters if the input string is empty or consists entirely of white
space, or if the first non-white-space character is other than a sign or a permissible letter
or digit.
-<p><!--para 5-->
+<p><!--para 5 -->
If the subject sequence has the expected form and the value of base is zero, the sequence
of characters starting with the first digit is interpreted as an integer constant according to
the rules of <a href="#6.4.4.1">6.4.4.1</a>. If the subject sequence has the expected form and the value of base
as given above. If the subject sequence begins with a minus sign, the value resulting from
the conversion is negated (in the return type). A pointer to the final string is stored in the
object pointed to by endptr, provided that endptr is not a null pointer.
-<p><!--para 6-->
+<p><!--para 6 -->
In other than the "C" locale, additional locale-specific subject sequence forms may be
accepted.
-<p><!--para 7-->
+<p><!--para 7 -->
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The strtol, strtoll, strtoul, and strtoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
is outside the range of representable values, LONG_MIN, LONG_MAX, LLONG_MIN,
LLONG_MAX, ULONG_MAX, or ULLONG_MAX is returned (according to the return type
and sign of the value, if any), and the value of the macro ERANGE is stored in errno.
-<!--page 364 indent 4-->
+<!--page 364 -->
<a name="7.22.2" href="#7.22.2"><h4>7.22.2 Pseudo-random sequence generation functions</h4></a>
<a name="7.22.2.1" href="#7.22.2.1"><h5>7.22.2.1 The rand function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int rand(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The rand function computes a sequence of pseudo-random integers in the range 0 to
RAND_MAX.<sup><a href="#note288"><b>288)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The rand function is not required to avoid data races. The implementation shall behave
as if no library function calls the rand function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The rand function returns a pseudo-random integer.
Environmental limits
-<p><!--para 5-->
+<p><!--para 5 -->
The value of the RAND_MAX macro shall be at least 32767.
<h6>footnotes</h6>
<a name="7.22.2.2" href="#7.22.2.2"><h5>7.22.2.2 The srand function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
void srand(unsigned int seed);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The srand function uses the argument as a seed for a new sequence of pseudo-random
numbers to be returned by subsequent calls to rand. If srand is then called with the
same seed value, the sequence of pseudo-random numbers shall be repeated. If rand is
called before any calls to srand have been made, the same sequence shall be generated
as when srand is first called with a seed value of 1.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the srand function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The srand function returns no value.
-<!--page 365 indent 4-->
-<p><!--para 5-->
+<!--page 365 -->
+<p><!--para 5 -->
EXAMPLE The following functions define a portable implementation of rand and srand.
<pre>
static unsigned long int next = 1;
<a name="7.22.3" href="#7.22.3"><h4>7.22.3 Memory management functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The order and contiguity of storage allocated by successive calls to the
aligned_alloc, calloc, malloc, and realloc functions is unspecified. The
pointer returned if the allocation succeeds is suitably aligned so that it may be assigned to
<a name="7.22.3.1" href="#7.22.3.1"><h5>7.22.3.1 The aligned_alloc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
void *aligned_alloc(size_t alignment, size_t size);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The aligned_alloc function allocates space for an object whose alignment is
specified by alignment, whose size is specified by size, and whose value is
indeterminate. The value of alignment shall be a valid alignment supported by the
implementation and the value of size shall be an integral multiple of alignment.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The aligned_alloc function returns either a null pointer or a pointer to the allocated
space.
-<!--page 366 indent 4-->
+<!--page 366 -->
<a name="7.22.3.2" href="#7.22.3.2"><h5>7.22.3.2 The calloc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
void *calloc(size_t nmemb, size_t size);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The calloc function allocates space for an array of nmemb objects, each of whose size
is size. The space is initialized to all bits zero.<sup><a href="#note289"><b>289)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The calloc function returns either a null pointer or a pointer to the allocated space.
<h6>footnotes</h6>
<a name="7.22.3.3" href="#7.22.3.3"><h5>7.22.3.3 The free function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
void free(void *ptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The free function causes the space pointed to by ptr to be deallocated, that is, made
available for further allocation. If ptr is a null pointer, no action occurs. Otherwise, if
the argument does not match a pointer earlier returned by a memory management
function, or if the space has been deallocated by a call to free or realloc, the
behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The free function returns no value.
<a name="7.22.3.4" href="#7.22.3.4"><h5>7.22.3.4 The malloc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
void *malloc(size_t size);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The malloc function allocates space for an object whose size is specified by size and
whose value is indeterminate.
-<!--page 367 indent 4-->
+<!--page 367 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The malloc function returns either a null pointer or a pointer to the allocated space.
<a name="7.22.3.5" href="#7.22.3.5"><h5>7.22.3.5 The realloc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
void *realloc(void *ptr, size_t size);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The realloc function deallocates the old object pointed to by ptr and returns a
pointer to a new object that has the size specified by size. The contents of the new
object shall be the same as that of the old object prior to deallocation, up to the lesser of
the new and old sizes. Any bytes in the new object beyond the size of the old object have
indeterminate values.
-<p><!--para 3-->
+<p><!--para 3 -->
If ptr is a null pointer, the realloc function behaves like the malloc function for the
specified size. Otherwise, if ptr does not match a pointer earlier returned by a memory
management function, or if the space has been deallocated by a call to the free or
realloc function, the behavior is undefined. If memory for the new object cannot be
allocated, the old object is not deallocated and its value is unchanged.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The realloc function returns a pointer to the new object (which may have the same
value as a pointer to the old object), or a null pointer if the new object could not be
allocated.
<a name="7.22.4.1" href="#7.22.4.1"><h5>7.22.4.1 The abort function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
_Noreturn void abort(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The abort function causes abnormal program termination to occur, unless the signal
SIGABRT is being caught and the signal handler does not return. Whether open streams
with unwritten buffered data are flushed, open streams are closed, or temporary files are
removed is implementation-defined. An implementation-defined form of the status
unsuccessful termination is returned to the host environment by means of the function
call raise(SIGABRT).
-<!--page 368 indent 4-->
+<!--page 368 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The abort function does not return to its caller.
<a name="7.22.4.2" href="#7.22.4.2"><h5>7.22.4.2 The atexit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int atexit(void (*func)(void));</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The atexit function registers the function pointed to by func, to be called without
arguments at normal program termination.<sup><a href="#note290"><b>290)</b></a></sup>
Environmental limits
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall support the registration of at least 32 functions.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The atexit function returns zero if the registration succeeds, nonzero if it fails.
<p><b> Forward references</b>: the at_quick_exit function (<a href="#7.22.4.3">7.22.4.3</a>), the exit function
(<a href="#7.22.4.4">7.22.4.4</a>).
<a name="7.22.4.3" href="#7.22.4.3"><h5>7.22.4.3 The at_quick_exit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int at_quick_exit(void (*func)(void));</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The at_quick_exit function registers the function pointed to by func, to be called
without arguments should quick_exit be called.<sup><a href="#note291"><b>291)</b></a></sup>
Environmental limits
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall support the registration of at least 32 functions.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The at_quick_exit function returns zero if the registration succeeds, nonzero if it
fails.
<p><b> Forward references</b>: the quick_exit function (<a href="#7.22.4.7">7.22.4.7</a>).
-<!--page 369 indent 4-->
+<!--page 369 -->
<h6>footnotes</h6>
<p><small><a name="note291" href="#note291">291)</a> The at_quick_exit function registrations are distinct from the atexit registrations, so
<a name="7.22.4.4" href="#7.22.4.4"><h5>7.22.4.4 The exit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
_Noreturn void exit(int status);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The exit function causes normal program termination to occur. No functions registered
by the at_quick_exit function are called. If a program calls the exit function
more than once, or calls the quick_exit function in addition to the exit function, the
behavior is undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
First, all functions registered by the atexit function are called, in the reverse order of
their registration,<sup><a href="#note292"><b>292)</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.
-<p><!--para 4-->
+<p><!--para 4 -->
Next, all open streams with unwritten buffered data are flushed, all open streams are
closed, and all files created by the tmpfile function are removed.
-<p><!--para 5-->
+<p><!--para 5 -->
Finally, control is returned to the host environment. If the value of status is zero or
EXIT_SUCCESS, an implementation-defined form of the status successful termination is
returned. If the value of status is EXIT_FAILURE, an implementation-defined form
of the status unsuccessful termination is returned. Otherwise the status returned is
implementation-defined.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The exit function cannot return to its caller.
<h6>footnotes</h6>
<a name="7.22.4.5" href="#7.22.4.5"><h5>7.22.4.5 The _Exit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
_Noreturn void _Exit(int status);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The _Exit function causes normal program termination to occur and control to be
returned to the host environment. No functions registered by the atexit function, the
at_quick_exit function, or signal handlers registered by the signal function are
called. The status returned to the host environment is determined in the same way as for
-<!--page 370 indent 4-->
+<!--page 370 -->
the exit function (<a href="#7.22.4.4">7.22.4.4</a>). Whether open streams with unwritten buffered data are
flushed, open streams are closed, or temporary files are removed is implementation-
defined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The _Exit function cannot return to its caller.
<a name="7.22.4.6" href="#7.22.4.6"><h5>7.22.4.6 The getenv function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
char *getenv(const char *name);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getenv function searches an environment list, provided by the host environment,
for a string that matches the string pointed to by name. The set of environment names
and the method for altering the environment list are implementation-defined. The
getenv function need not avoid data races with other threads of execution that modify
the environment list.<sup><a href="#note293"><b>293)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the getenv function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The getenv function returns a pointer to a string associated with the matched list
member. The string pointed to shall not be modified by the program, but may be
overwritten by a subsequent call to the getenv function. If the specified name cannot
<a name="7.22.4.7" href="#7.22.4.7"><h5>7.22.4.7 The quick_exit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
_Noreturn void quick_exit(int status);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The quick_exit function causes normal program termination to occur. No functions
registered by the atexit function or signal handlers registered by the signal function
are called. If a program calls the quick_exit function more than once, or calls the
exit function in addition to the quick_exit function, the behavior is undefined.
-<p><!--para 3-->
+<p><!--para 3 -->
The quick_exit function first calls all functions registered by the at_quick_exit
function, in the reverse order of their registration,<sup><a href="#note294"><b>294)</b></a></sup> except that a function is called after
-<!--page 371 indent 4-->
+<!--page 371 -->
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.
-<p><!--para 4-->
+<p><!--para 4 -->
Then control is returned to the host environment by means of the function call
_Exit(status).
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The quick_exit function cannot return to its caller.
<h6>footnotes</h6>
<a name="7.22.4.8" href="#7.22.4.8"><h5>7.22.4.8 The system function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int system(const char *string);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If string is a null pointer, the system function determines whether the host
environment has a command processor. If string is not a null pointer, the system
function passes the string pointed to by string to that command processor to be
executed in a manner which the implementation shall document; this might then cause the
program calling system to behave in a non-conforming manner or to terminate.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a null pointer, the system function returns nonzero only if a
command processor is available. If the argument is not a null pointer, and the system
function does return, it returns an implementation-defined value.
<a name="7.22.5" href="#7.22.5"><h4>7.22.5 Searching and sorting utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
These utilities make use of a comparison function to search or sort arrays of unspecified
type. Where an argument declared as size_t nmemb specifies the length of the array
for a function, nmemb can have the value zero on a call to that function; the comparison
function is not called, a search finds no matching element, and sorting performs no
rearrangement. Pointer arguments on such a call shall still have valid values, as described
in <a href="#7.1.4">7.1.4</a>.
-<p><!--para 2-->
+<p><!--para 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.<sup><a href="#note295"><b>295)</b></a></sup> The first argument when called from bsearch
-<!--page 372 indent 4-->
-<p><!--para 3-->
+<!--page 372 -->
+<p><!--para 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
alter the contents of any individual element.
-<p><!--para 4-->
+<p><!--para 4 -->
When the same objects (consisting of size bytes, irrespective of their current positions
in the array) are passed more than once to the comparison function, the results shall be
consistent with one another. That is, for qsort they shall define a total ordering on the
array, and for bsearch the same object shall always compare the same way with the
key.
-<p><!--para 5-->
+<p><!--para 5 -->
A sequence point occurs immediately before and immediately after each call to the
comparison function, and also between any call to the comparison function and any
movement of the objects passed as arguments to that call.
<a name="7.22.5.1" href="#7.22.5.1"><h5>7.22.5.1 The bsearch function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
void *bsearch(const void *key, const void *base,
size_t nmemb, size_t size,
int (*compar)(const void *, const void *));</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The bsearch function searches an array of nmemb objects, the initial element of which
is pointed to by base, for an element that matches the object pointed to by key. The
size of each element of the array is specified by size.
-<p><!--para 3-->
+<p><!--para 3 -->
The comparison function pointed to by compar is called with two arguments that point
to the key object and to an array element, in that order. The function shall return an
integer less than, equal to, or greater than zero if the key object is considered,
shall consist of: all the elements that compare less than, all the elements that compare
equal to, and all the elements that compare greater than the key object, in that order.<sup><a href="#note296"><b>296)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The bsearch function returns a pointer to a matching element of the array, or a null
pointer if no match is found. If two elements compare as equal, which element is
-<!--page 373 indent 4-->
+<!--page 373 -->
matched is unspecified.
<h6>footnotes</h6>
<a name="7.22.5.2" href="#7.22.5.2"><h5>7.22.5.2 The qsort function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
void qsort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *));</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The qsort function sorts an array of nmemb objects, the initial element of which is
pointed to by base. The size of each object is specified by size.
-<p><!--para 3-->
+<p><!--para 3 -->
The contents of the array are sorted into ascending order according to a comparison
function pointed to by compar, which is called with two arguments that point to the
objects being compared. The function shall return an integer less than, equal to, or
greater than zero if the first argument is considered to be respectively less than, equal to,
or greater than the second.
-<p><!--para 4-->
+<p><!--para 4 -->
If two elements compare as equal, their order in the resulting sorted array is unspecified.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The qsort function returns no value.
<a name="7.22.6" href="#7.22.6"><h4>7.22.6 Integer arithmetic functions</h4></a>
<a name="7.22.6.1" href="#7.22.6.1"><h5>7.22.6.1 The abs, labs and llabs functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int abs(int j);
long int labs(long int j);
long long int llabs(long long int j);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The abs, labs, and llabs functions compute the absolute value of an integer j. If the
result cannot be represented, the behavior is undefined.<sup><a href="#note297"><b>297)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The abs, labs, and llabs, functions return the absolute value.
-<!--page 374 indent 4-->
+<!--page 374 -->
<h6>footnotes</h6>
<p><small><a name="note297" href="#note297">297)</a> The absolute value of the most negative number cannot be represented in two's complement.
<a name="7.22.6.2" href="#7.22.6.2"><h5>7.22.6.2 The div, ldiv, and lldiv functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
div_t div(int numer, int denom);
ldiv_t ldiv(long int numer, long int denom);
lldiv_t lldiv(long long int numer, long long int denom);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The div, ldiv, and lldiv, functions compute numer / denom and numer %
denom in a single operation.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The div, ldiv, and lldiv functions return a structure of type div_t, ldiv_t, and
lldiv_t, respectively, comprising both the quotient and the remainder. The structures
shall contain (in either order) the members quot (the quotient) and rem (the remainder),
the result cannot be represented, the behavior is undefined.
<a name="7.22.7" href="#7.22.7"><h4>7.22.7 Multibyte/wide character conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior of the multibyte character functions is affected by the LC_CTYPE category
of the current locale. For a state-dependent encoding, each function is placed into its
initial conversion state at program startup and can be returned to that state by a call for
<a name="7.22.7.1" href="#7.22.7.1"><h5>7.22.7.1 The mblen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int mblen(const char *s, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is not a null pointer, the mblen function determines the number of bytes contained
in the multibyte character pointed to by s. Except that the conversion state of the
mbtowc function is not affected, it is equivalent to
-<!--page 375 indent 4-->
-<p><!--para 3-->
+<!--page 375 -->
+<p><!--para 3 -->
<pre>
mbtowc((wchar_t *)0, (const char *)0, 0);
mbtowc((wchar_t *)0, s, n);</pre>
The implementation shall behave as if no library function calls the mblen function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If s is a null pointer, the mblen function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
not a null pointer, the mblen function either returns 0 (if s points to the null character),
<a name="7.22.7.2" href="#7.22.7.2"><h5>7.22.7.2 The mbtowc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int mbtowc(wchar_t * restrict pwc,
const char * restrict s,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is not a null pointer, the mbtowc function inspects at most n bytes beginning with
the byte pointed to by s to determine the number of bytes needed to complete the next
multibyte character (including any shift sequences). If the function determines that the
corresponding wide character and then, if pwc is not a null pointer, stores that value in
the object pointed to by pwc. If the corresponding wide character is the null wide
character, the function is left in the initial conversion state.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the mbtowc function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If s is a null pointer, the mbtowc function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
not a null pointer, the mbtowc function either returns 0 (if s points to the null character),
or returns the number of bytes that are contained in the converted multibyte character (if
the next n or fewer bytes form a valid multibyte character), or returns -1 (if they do not
form a valid multibyte character).
-<p><!--para 5-->
+<p><!--para 5 -->
In no case will the value returned be greater than n or the value of the MB_CUR_MAX
macro.
-<!--page 376 indent 4-->
+<!--page 376 -->
<a name="7.22.7.3" href="#7.22.7.3"><h5>7.22.7.3 The wctomb function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
int wctomb(char *s, wchar_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wctomb function determines the number of bytes needed to represent the multibyte
character corresponding to the wide character given by wc (including any shift
sequences), and stores the multibyte character representation in the array whose first
are stored. If wc is a null wide character, a null byte is stored, preceded by any shift
sequence needed to restore the initial shift state, and the function is left in the initial
conversion state.
-<p><!--para 3-->
+<p><!--para 3 -->
The implementation shall behave as if no library function calls the wctomb function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If s is a null pointer, the wctomb function returns a nonzero or zero value, if multibyte
character encodings, respectively, do or do not have state-dependent encodings. If s is
not a null pointer, the wctomb function returns -1 if the value of wc does not correspond
to a valid multibyte character, or returns the number of bytes that are contained in the
multibyte character corresponding to the value of wc.
-<p><!--para 5-->
+<p><!--para 5 -->
In no case will the value returned be greater than the value of the MB_CUR_MAX macro.
<a name="7.22.8" href="#7.22.8"><h4>7.22.8 Multibyte/wide string conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior of the multibyte string functions is affected by the LC_CTYPE category of
the current locale.
<a name="7.22.8.1" href="#7.22.8.1"><h5>7.22.8.1 The mbstowcs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
size_t mbstowcs(wchar_t * restrict pwcs,
const char * restrict s,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mbstowcs function converts a sequence of multibyte characters that begins in the
initial shift state from the array pointed to by s into a sequence of corresponding wide
characters and stores not more than n wide characters into the array pointed to by pwcs.
No multibyte characters that follow a null character (which is converted into a null wide
character) will be examined or converted. Each multibyte character is converted as if by
a call to the mbtowc function, except that the conversion state of the mbtowc function is
-<!--page 377 indent 4-->
+<!--page 377 -->
not affected.
-<p><!--para 3-->
+<p><!--para 3 -->
No more than n elements will be modified in the array pointed to by pwcs. If copying
takes place between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If an invalid multibyte character is encountered, the mbstowcs function returns
(size_t)(-1). Otherwise, the mbstowcs function returns the number of array
elements modified, not including a terminating null wide character, if any.<sup><a href="#note299"><b>299)</b></a></sup>
<a name="7.22.8.2" href="#7.22.8.2"><h5>7.22.8.2 The wcstombs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
size_t wcstombs(char * restrict s,
const wchar_t * restrict pwcs,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcstombs function converts a sequence of wide characters from the array pointed
to by pwcs into a sequence of corresponding multibyte characters that begins in the
initial shift state, and stores these multibyte characters into the array pointed to by s,
stopping if a multibyte character would exceed the limit of n total bytes or if a null
character is stored. Each wide character is converted as if by a call to the wctomb
function, except that the conversion state of the wctomb function is not affected.
-<p><!--para 3-->
+<p><!--para 3 -->
No more than n bytes will be modified in the array pointed to by s. If copying takes place
between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If a wide character is encountered that does not correspond to a valid multibyte character,
the wcstombs function returns (size_t)(-1). Otherwise, the wcstombs function
returns the number of bytes modified, not including a terminating null character, if
-<!--page 378 indent 4-->
+<!--page 378 -->
<a name="7.23" href="#7.23"><h3>7.23 String handling <string.h></h3></a>
<a name="7.23.1" href="#7.23.1"><h4>7.23.1 String function conventions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.23"><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.<sup><a href="#note300"><b>300)</b></a></sup> The type is size_t and the macro is NULL (both described in
<a href="#7.19">7.19</a>). Various methods are used for determining the lengths of the arrays, but in all cases
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.
-<p><!--para 2-->
+<p><!--para 2 -->
Where an argument declared as size_t n specifies the length of the array for a
function, n can have the value zero on a call to that function. Unless explicitly stated
otherwise in the description of a particular function in this subclause, pointer arguments
function that locates a character finds no occurrence, a function that compares two
character sequences returns zero, and a function that copies characters copies zero
characters.
-<p><!--para 3-->
+<p><!--para 3 -->
For all functions in this subclause, each character shall be interpreted as if it had the type
unsigned char (and therefore every possible object representation is valid and has a
different value).
<a name="7.23.2.1" href="#7.23.2.1"><h5>7.23.2.1 The memcpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
void *memcpy(void * restrict s1,
const void * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memcpy function copies n characters from the object pointed to by s2 into the
object pointed to by s1. If copying takes place between objects that overlap, the behavior
is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memcpy function returns the value of s1.
-<!--page 379 indent 4-->
+<!--page 379 -->
<a name="7.23.2.2" href="#7.23.2.2"><h5>7.23.2.2 The memmove function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
void *memmove(void *s1, const void *s2, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memmove function copies n characters from the object pointed to by s2 into the
object pointed to by s1. Copying takes place as if the n characters from the object
pointed to by s2 are first copied into a temporary array of n characters that does not
overlap the objects pointed to by s1 and s2, and then the n characters from the
temporary array are copied into the object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memmove function returns the value of s1.
<a name="7.23.2.3" href="#7.23.2.3"><h5>7.23.2.3 The strcpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strcpy(char * restrict s1,
const char * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcpy function copies the string pointed to by s2 (including the terminating null
character) into the array pointed to by s1. If copying takes place between objects that
overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcpy function returns the value of s1.
<a name="7.23.2.4" href="#7.23.2.4"><h5>7.23.2.4 The strncpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strncpy(char * restrict s1,
const char * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strncpy function copies not more than n characters (characters that follow a null
character are not copied) from the array pointed to by s2 to the array pointed to by
-<!--page 380 indent 4-->
+<!--page 380 -->
s1.<sup><a href="#note301"><b>301)</b></a></sup> If copying takes place between objects that overlap, the behavior is undefined.
-<p><!--para 3-->
+<p><!--para 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.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The strncpy function returns the value of s1.
<h6>footnotes</h6>
<a name="7.23.3.1" href="#7.23.3.1"><h5>7.23.3.1 The strcat function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strcat(char * restrict s1,
const char * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcat function appends a copy of the string pointed to by s2 (including the
terminating null character) to the end of the string pointed to by s1. The initial character
of s2 overwrites the null character at the end of s1. If copying takes place between
objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcat function returns the value of s1.
<a name="7.23.3.2" href="#7.23.3.2"><h5>7.23.3.2 The strncat function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strncat(char * restrict s1,
const char * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strncat function appends not more than n characters (a null character and
characters that follow it are not appended) from the array pointed to by s2 to the end of
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.<sup><a href="#note302"><b>302)</b></a></sup> If copying
-<!--page 381 indent 4-->
+<!--page 381 -->
takes place between objects that overlap, the behavior is undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strncat function returns the value of s1.
<p><b> Forward references</b>: the strlen function (<a href="#7.23.6.3">7.23.6.3</a>).
</small>
<a name="7.23.4" href="#7.23.4"><h4>7.23.4 Comparison functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The sign of a nonzero value returned by the comparison functions memcmp, strcmp,
and strncmp is determined by the sign of the difference between the values of the first
pair of characters (both interpreted as unsigned char) that differ in the objects being
<a name="7.23.4.1" href="#7.23.4.1"><h5>7.23.4.1 The memcmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
int memcmp(const void *s1, const void *s2, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memcmp function compares the first n characters of the object pointed to by s1 to
the first n characters of the object pointed to by s2.<sup><a href="#note303"><b>303)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
pointed to by s2.
<a name="7.23.4.2" href="#7.23.4.2"><h5>7.23.4.2 The strcmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
int strcmp(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcmp function compares the string pointed to by s1 to the string pointed to by
s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
-<!--page 382 indent 4-->
+<!--page 382 -->
pointed to by s2.
<a name="7.23.4.3" href="#7.23.4.3"><h5>7.23.4.3 The strcoll function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
int strcoll(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcoll function compares the string pointed to by s1 to the string pointed to by
s2, both interpreted as appropriate to the LC_COLLATE category of the current locale.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcoll function returns an integer greater than, equal to, or less than zero,
accordingly as the string pointed to by s1 is greater than, equal to, or less than the string
pointed to by s2 when both are interpreted as appropriate to the current locale.
<a name="7.23.4.4" href="#7.23.4.4"><h5>7.23.4.4 The strncmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
int strncmp(const char *s1, const char *s2, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strncmp function compares not more than n characters (characters that follow a
null character are not compared) from the array pointed to by s1 to the array pointed to
by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
<a name="7.23.4.5" href="#7.23.4.5"><h5>7.23.4.5 The strxfrm function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
size_t strxfrm(char * restrict s1,
const char * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strxfrm function transforms the string pointed to by s2 and places the resulting
string into the array pointed to by s1. The transformation is such that if the strcmp
function is applied to two transformed strings, it returns a value greater than, equal to, or
-<!--page 383 indent 4-->
+<!--page 383 -->
less than zero, corresponding to the result of the strcoll function applied to the same
two original strings. No more than n characters are placed into the resulting array
pointed to by s1, including the terminating null character. If n is zero, s1 is permitted to
be a null pointer. If copying takes place between objects that overlap, the behavior is
undefined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strxfrm function returns the length of the transformed string (not including the
terminating null character). If the value returned is n or more, the contents of the array
pointed to by s1 are indeterminate.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The value of the following expression is the size of the array needed to hold the
transformation of the string pointed to by s.
<pre>
<a name="7.23.5.1" href="#7.23.5.1"><h5>7.23.5.1 The memchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
void *memchr(const void *s, int c, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memchr function locates the first occurrence of c (converted to an unsigned
char) in the initial n characters (each interpreted as unsigned char) of the object
pointed to by s. The implementation shall behave as if it reads the characters sequentially
and stops as soon as a matching character is found.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the object.
<a name="7.23.5.2" href="#7.23.5.2"><h5>7.23.5.2 The strchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strchr(const char *s, int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strchr function locates the first occurrence of c (converted to a char) in the
string pointed to by s. The terminating null character is considered to be part of the
string.
-<!--page 384 indent 4-->
+<!--page 384 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strchr function returns a pointer to the located character, or a null pointer if the
character does not occur in the string.
<a name="7.23.5.3" href="#7.23.5.3"><h5>7.23.5.3 The strcspn function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
size_t strcspn(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strcspn function computes the length of the maximum initial segment of the string
pointed to by s1 which consists entirely of characters not from the string pointed to by
s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strcspn function returns the length of the segment.
<a name="7.23.5.4" href="#7.23.5.4"><h5>7.23.5.4 The strpbrk function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strpbrk(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strpbrk function locates the first occurrence in the string pointed to by s1 of any
character from the string pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strpbrk function returns a pointer to the character, or a null pointer if no character
from s2 occurs in s1.
<a name="7.23.5.5" href="#7.23.5.5"><h5>7.23.5.5 The strrchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strrchr(const char *s, int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strrchr function locates the last occurrence of c (converted to a char) in the
string pointed to by s. The terminating null character is considered to be part of the
string.
-<!--page 385 indent 4-->
+<!--page 385 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strrchr function returns a pointer to the character, or a null pointer if c does not
occur in the string.
<a name="7.23.5.6" href="#7.23.5.6"><h5>7.23.5.6 The strspn function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
size_t strspn(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strspn function computes the length of the maximum initial segment of the string
pointed to by s1 which consists entirely of characters from the string pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strspn function returns the length of the segment.
<a name="7.23.5.7" href="#7.23.5.7"><h5>7.23.5.7 The strstr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strstr(const char *s1, const char *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strstr function locates the first occurrence in the string pointed to by s1 of the
sequence of characters (excluding the terminating null character) in the string pointed to
by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strstr function returns a pointer to the located string, or a null pointer if the string
is not found. If s2 points to a string with zero length, the function returns s1.
<a name="7.23.5.8" href="#7.23.5.8"><h5>7.23.5.8 The strtok function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strtok(char * restrict s1,
const char * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A sequence of calls to the strtok function breaks the string pointed to by s1 into a
sequence of tokens, each of which is delimited by a character from the string pointed to
by s2. The first call in the sequence has a non-null first argument; subsequent calls in the
sequence have a null first argument. The separator string pointed to by s2 may be
different from call to call.
-<!--page 386 indent 4-->
-<p><!--para 3-->
+<!--page 386 -->
+<p><!--para 3 -->
The first call in the sequence searches the string pointed to by s1 for the first character
that is not contained in the current separator string pointed to by s2. If no such character
is found, then there are no tokens in the string pointed to by s1 and the strtok function
returns a null pointer. If such a character is found, it is the start of the first token.
-<p><!--para 4-->
+<p><!--para 4 -->
The strtok function then searches from there for a character that is contained in the
current separator string. If no such character is found, the current token extends to the
end of the string pointed to by s1, and subsequent searches for a token will return a null
pointer. If such a character is found, it is overwritten by a null character, which
terminates the current token. The strtok function saves a pointer to the following
character, from which the next search for a token will start.
-<p><!--para 5-->
+<p><!--para 5 -->
Each subsequent call, with a null pointer as the value of the first argument, starts
searching from the saved pointer and behaves as described above.
-<p><!--para 6-->
+<p><!--para 6 -->
The strtok function is not required to avoid data races. The implementation shall
behave as if no library function calls the strtok function.
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The strtok function returns a pointer to the first character of a token, or a null pointer
if there is no token.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE
<pre>
#include <a href="#7.23"><string.h></a>
<a name="7.23.6.1" href="#7.23.6.1"><h5>7.23.6.1 The memset function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
void *memset(void *s, int c, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The memset function copies the value of c (converted to an unsigned char) into
each of the first n characters of the object pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The memset function returns the value of s.
-<!--page 387 indent 4-->
+<!--page 387 -->
<a name="7.23.6.2" href="#7.23.6.2"><h5>7.23.6.2 The strerror function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
char *strerror(int errnum);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strerror function maps the number in errnum to a message string. Typically,
the values for errnum come from errno, but strerror shall map any value of type
int to a message.
-<p><!--para 3-->
+<p><!--para 3 -->
The strerror function is not required to avoid data races. The implementation shall
behave as if no library function calls the strerror function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The strerror function returns a pointer to the string, the contents of which are locale-
specific. The array pointed to shall not be modified by the program, but may be
overwritten by a subsequent call to the strerror function.
<a name="7.23.6.3" href="#7.23.6.3"><h5>7.23.6.3 The strlen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.23"><string.h></a>
size_t strlen(const char *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strlen function computes the length of the string pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strlen function returns the number of characters that precede the terminating null
character.
-<!--page 388 indent 4-->
+<!--page 388 -->
<a name="7.24" href="#7.24"><h3>7.24 Type-generic math <tgmath.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.24"><tgmath.h></a> includes the headers <a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> and
defines several type-generic macros.
-<p><!--para 2-->
+<p><!--para 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
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.<sup><a href="#note305"><b>305)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
Use of the macro invokes a function whose generic parameters have the corresponding
real type determined as follows:
<ul>
type, the type determined is double.
<li> Otherwise, the type determined is float.
</ul>
-<p><!--para 4-->
+<p><!--para 4 -->
For each unsuffixed function in <a href="#7.12"><math.h></a> for which there is a function in
<a href="#7.3"><complex.h></a> with the same name except for a c prefix, the corresponding type-
generic macro (for both functions) has the same name as the function in <a href="#7.12"><math.h></a>. The
-<!--page 389 indent 4-->
+<!--page 389 -->
<pre>
<a href="#7.12"><math.h></a> <a href="#7.3"><complex.h></a> type-generic
function function macro
fabs cabs fabs</pre>
If at least one argument for a generic parameter is complex, then use of the macro invokes
a complex function; otherwise, use of the macro invokes a real function.
-<p><!--para 5-->
+<p><!--para 5 -->
For each unsuffixed function in <a href="#7.12"><math.h></a> without a c-prefixed counterpart in
<a href="#7.3"><complex.h></a> (except modf), the corresponding type-generic macro has the same
name as the function. These type-generic macros are:
floor llrint nexttoward</pre>
If all arguments for generic parameters are real, then use of the macro invokes a real
function; otherwise, use of the macro results in undefined behavior.
-<!--page 390 indent 4-->
-<p><!--para 6-->
+<!--page 390 -->
+<p><!--para 6 -->
For each unsuffixed function in <a href="#7.3"><complex.h></a> that is not a c-prefixed counterpart to a
function in <a href="#7.12"><math.h></a>, the corresponding type-generic macro has the same name as the
function. These type-generic macros are:
carg conj creal
cimag cproj</pre>
Use of the macro with any real or complex argument invokes a complex function.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE With the declarations
<pre>
#include <a href="#7.24"><tgmath.h></a>
double complex dc;
long double complex ldc;</pre>
functions invoked by use of type-generic macros are shown in the following table:
-<!--page 391 indent 4-->
+<!--page 391 -->
<pre>
macro use invokes
exp(n) exp(n), the function
<a name="7.25" href="#7.25"><h3>7.25 Threads <threads.h></h3></a>
<a name="7.25.1" href="#7.25.1"><h4>7.25.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.25"><threads.h></a> defines macros, and declares types, enumeration constants,
and functions that support multiple threads of execution.
-<p><!--para 2-->
+<p><!--para 2 -->
Implementations that define the macro __STDC_NO_THREADS__ need not provide
this header nor support any of its facilities.
-<p><!--para 3-->
+<p><!--para 3 -->
The macros are
<pre>
ONCE_FLAG_INIT</pre>
TSS_DTOR_ITERATIONS</pre>
which expands to an integer constant expression representing the maximum number of
times that destructors will be called when a thread terminates.
-<p><!--para 4-->
+<p><!--para 4 -->
The types are
<pre>
cnd_t</pre>
<pre>
once_flag</pre>
which is a complete object type that holds a flag for use by call_once; and
-<!--page 392 indent 4-->
+<!--page 392 -->
<pre>
xtime</pre>
which is a structure type that holds a time specified in seconds and nanoseconds. The
structure shall contain at least the following members, in any order.
-<p><!--para 5-->
+<p><!--para 5 -->
<pre>
time_t sec;
long nsec;</pre>
thrd_nomem</pre>
which is returned by a function to indicate that the requested operation failed because it
was unable to allocate memory.
-<!--page 393 indent 4-->
+<!--page 393 -->
<a name="7.25.2" href="#7.25.2"><h4>7.25.2 Initialization functions</h4></a>
<a name="7.25.2.1" href="#7.25.2.1"><h5>7.25.2.1 The call_once function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
void call_once(once_flag *flag, void (*func)(void));</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The call_once function uses the once_flag pointed to by flag to ensure that
func is called exactly once, the first time the call_once function is called with that
value of flag. Completion of an effective call to the call_once function synchronizes
with all subsequent calls to the call_once function with the same value of flag.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The call_once function returns no value.
<a name="7.25.3" href="#7.25.3"><h4>7.25.3 Condition variable functions</h4></a>
<a name="7.25.3.1" href="#7.25.3.1"><h5>7.25.3.1 The cnd_broadcast function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int cnd_broadcast(cnd_t *cond);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cnd_broadcast function unblocks all of the threads that are blocked on the
condition variable pointed to by cond at the time of the call. If no threads are blocked
on the condition variable pointed to by cond at the time of the call, the function does
nothing.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cnd_broadcast function returns thrd_success on success, or thrd_error
if the request could not be honored.
<a name="7.25.3.2" href="#7.25.3.2"><h5>7.25.3.2 The cnd_destroy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
void cnd_destroy(cnd_t *cond);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cnd_destroy function releases all resources used by the condition variable
pointed to by cond. The cnd_destroy function requires that no threads be blocked
waiting for the condition variable pointed to by cond.
-<!--page 394 indent 4-->
+<!--page 394 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cnd_destroy function returns no value.
<a name="7.25.3.3" href="#7.25.3.3"><h5>7.25.3.3 The cnd_init function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int cnd_init(cnd_t *cond);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cnd_init function creates a condition variable. If it succeeds it sets the variable
pointed to by cond to a value that uniquely identifies the newly created condition
variable. A thread that calls cnd_wait on a newly created condition variable will
block.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cnd_init function returns thrd_success on success, or thrd_nomem if no
memory could be allocated for the newly created condition, or thrd_error if the
request could not be honored.
<a name="7.25.3.4" href="#7.25.3.4"><h5>7.25.3.4 The cnd_signal function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int cnd_signal(cnd_t *cond);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cnd_signal function unblocks one of the threads that are blocked on the
condition variable pointed to by cond at the time of the call. If no threads are blocked
on the condition variable at the time of the call, the function does nothing and return
success.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cnd_signal function returns thrd_success on success or thrd_error if
the request could not be honored.
<a name="7.25.3.5" href="#7.25.3.5"><h5>7.25.3.5 The cnd_timedwait function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 395 indent 4-->
+<p><!--para 1 -->
+<!--page 395 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int cnd_timedwait(cnd_t *cond, mtx_t *mtx,
const xtime *xt);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cnd_timedwait function atomically unlocks the mutex pointed to by mtx and
endeavors to block until the condition variable pointed to by cond is signaled by a call to
cnd_signal or to cnd_broadcast, or until after the time specified by the xtime
pointed to by mtx before it returns. The cnd_timedwait function requires that the
mutex pointed to by mtx be locked by the calling thread.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cnd_timedwait function returns thrd_success upon success, or
thrd_timeout if the time specified in the call was reached without acquiring the
requested resource, or thrd_error if the request could not be honored.
<a name="7.25.3.6" href="#7.25.3.6"><h5>7.25.3.6 The cnd_wait function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int cnd_wait(cnd_t *cond, mtx_t *mtx);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The cnd_wait function atomically unlocks the mutex pointed to by mtx and endeavors
to block until the condition variable pointed to by cond is signaled by a call to
cnd_signal or to cnd_broadcast. When the calling thread becomes unblocked it
not locked by the calling thread, the cnd_wait function will act as if the abort
function is called.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The cnd_wait function returns thrd_success on success or thrd_error if the
request could not be honored.
<a name="7.25.4.1" href="#7.25.4.1"><h5>7.25.4.1 The mtx_destroy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
void mtx_destroy(mtx_t *mtx);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mtx_destroy function releases any resources used by the mutex pointed to by
mtx. No threads can be blocked waiting for the mutex pointed to by mtx.
-<!--page 396 indent 4-->
+<!--page 396 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mtx_destroy function returns no value.
<a name="7.25.4.2" href="#7.25.4.2"><h5>7.25.4.2 The mtx_init function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int mtx_init(mtx_t *mtx, int type);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mtx_init function creates a mutex object with properties indicated by type,
which must have one of the six values:
mtx_plain for a simple non-recursive mutex,
mtx_plain | mtx_recursive for a simple recursive mutex,
mtx_timed | mtx_recursive for a recursive mutex that supports timeout, or
mtx_try | mtx_recursive for a recursive mutex that supports test and return.
-<p><!--para 3-->
+<p><!--para 3 -->
If the mtx_init function succeeds, it sets the mutex pointed to by mtx to a value that
uniquely identifies the newly created mutex.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The mtx_init function returns thrd_success on success, or thrd_error if the
request could not be honored.
<a name="7.25.4.3" href="#7.25.4.3"><h5>7.25.4.3 The mtx_lock function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int mtx_lock(mtx_t *mtx);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mtx_lock function blocks until it locks the mutex pointed to by mtx. If the mutex
is non-recursive, it shall not be locked by the calling thread. Prior calls to mtx_unlock
on the same mutex shall synchronize with this operation.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mtx_lock function returns thrd_success on success, or thrd_busy if the
resource requested is already in use, or thrd_error if the request could not be
honored.
-<!--page 397 indent 4-->
+<!--page 397 -->
<a name="7.25.4.4" href="#7.25.4.4"><h5>7.25.4.4 The mtx_timedlock function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int mtx_timedlock(mtx_t *mtx, const xtime *xt);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mtx_timedlock function endeavors to block until it locks the mutex pointed to by
mtx or until the time specified by the xtime object xt has passed. The specified mutex
shall support timeout. If the operation succeeds, prior calls to mtx_unlock on the same
mutex shall synchronize with this operation.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mtx_timedlock function returns thrd_success on success, or thrd_busy
if the resource requested is already in use, or thrd_timeout if the time specified was
reached without acquiring the requested resource, or thrd_error if the request could
<a name="7.25.4.5" href="#7.25.4.5"><h5>7.25.4.5 The mtx_trylock function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int mtx_trylock(mtx_t *mtx);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mtx_trylock function endeavors to lock the mutex pointed to by mtx. The
specified mutex shall support either test and return or timeout. If the mutex is already
locked, the function returns without blocking. If the operation succeeds, prior calls to
mtx_unlock on the same mutex shall synchronize with this operation.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mtx_trylock function returns thrd_success on success, or thrd_busy if
the resource requested is already in use, or thrd_error if the request could not be
honored.
<a name="7.25.4.6" href="#7.25.4.6"><h5>7.25.4.6 The mtx_unlock function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int mtx_unlock(mtx_t *mtx);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mtx_unlock function unlocks the mutex pointed to by mtx. The mutex pointed to
by mtx shall be locked by the calling thread.
-<!--page 398 indent 4-->
+<!--page 398 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mtx_unlock function returns thrd_success on success or thrd_error if
the request could not be honored.
<a name="7.25.5.1" href="#7.25.5.1"><h5>7.25.5.1 The thrd_create function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int thrd_create(thrd_t *thr, thrd_start_t func,
void *arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The thrd_create function creates a new thread executing func(arg). If the
thrd_create function succeeds, it sets the object pointed to by thr to the identifier of
the newly created thread. (A thread's identifier may be reused for a different thread once
completion of the thrd_create function synchronizes with the beginning of the
execution of the new thread.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The thrd_create function returns thrd_success on success, or thrd_nomem if
no memory could be allocated for the thread requested, or thrd_error if the request
could not be honored.
<a name="7.25.5.2" href="#7.25.5.2"><h5>7.25.5.2 The thrd_current function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
thrd_t thrd_current(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The thrd_current function identifies the thread that called it.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The thrd_current function returns the identifier of the thread that called it.
<a name="7.25.5.3" href="#7.25.5.3"><h5>7.25.5.3 The thrd_detach function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 399 indent 4-->
+<p><!--para 1 -->
+<!--page 399 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int thrd_detach(thrd_t thr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The thrd_detach function tells the operating system to dispose of any resources
allocated to the thread identified by thr when that thread terminates. The thread
identified by thr shall not have been previously detached or joined with another thread.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The thrd_detach function returns thrd_success on success or thrd_error if
the request could not be honored.
<a name="7.25.5.4" href="#7.25.5.4"><h5>7.25.5.4 The thrd_equal function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int thrd_equal(thrd_t thr0, thrd_t thr1);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The thrd_equal function will determine whether the thread identified by thr0 refers
to the thread identified by thr1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The thrd_equal function returns zero if the thread thr0 and the thread thr1 refer to
different threads. Otherwise the thrd_equal function returns a nonzero value.
<a name="7.25.5.5" href="#7.25.5.5"><h5>7.25.5.5 The thrd_exit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
void thrd_exit(int res);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The thrd_exit function terminates execution of the calling thread and sets its result
code to res.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The thrd_exit function returns no value.
<a name="7.25.5.6" href="#7.25.5.6"><h5>7.25.5.6 The thrd_join function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int thrd_join(thrd_t thr, int *res);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The thrd_join function joins the thread identified by thr with the current thread by
blocking until the other thread has terminated. If the parameter res is not a null pointer,
-<!--page 400 indent 4-->
+<!--page 400 -->
it stores the thread's result code in the integer pointed to by res. The termination of the
other thread synchronizes with the completion of the thrd_join function. The thread
identified by thr shall not have been previously detached or joined with another thread.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The thrd_join function returns thrd_success on success or thrd_error if the
request could not be honored.
<a name="7.25.5.7" href="#7.25.5.7"><h5>7.25.5.7 The thrd_sleep function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
void thrd_sleep(const xtime *xt);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The thrd_sleep function suspends execution of the calling thread until after the time
specified by the xtime object pointed to by xt.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The thrd_sleep function returns no value.
<a name="7.25.5.8" href="#7.25.5.8"><h5>7.25.5.8 The thrd_yield function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
void thrd_yield(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The thrd_yield function endeavors to permit other threads to run, even if the current
thread would ordinarily continue to run.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The thrd_yield function returns no value.
<a name="7.25.6" href="#7.25.6"><h4>7.25.6 Thread-specific storage functions</h4></a>
<a name="7.25.6.1" href="#7.25.6.1"><h5>7.25.6.1 The tss_create function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int tss_create(tss_t *key, tss_dtor_t dtor);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tss_create function creates a thread-specific storage pointer with destructor
dtor, which may be null.
-<!--page 401 indent 4-->
+<!--page 401 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the tss_create function is successful, it sets the thread-specific storage pointed to
by key to a value that uniquely identifies the newly created pointer and returns
thrd_success; otherwise, thrd_error is returned and the thread-specific storage
<a name="7.25.6.2" href="#7.25.6.2"><h5>7.25.6.2 The tss_delete function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
void tss_delete(tss_t key);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tss_delete function releases any resources used by the thread-specific storage
identified by key.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tss_delete function returns no value.
<a name="7.25.6.3" href="#7.25.6.3"><h5>7.25.6.3 The tss_get function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
void *tss_get(tss_t key);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tss_get function returns the value for the current thread held in the thread-specific
storage identified by key.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tss_get function returns the value for the current thread if successful, or zero if
unsuccessful.
<a name="7.25.6.4" href="#7.25.6.4"><h5>7.25.6.4 The tss_set function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int tss_set(tss_t key, void *val);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The tss_set function sets the value for the current thread held in the thread-specific
storage identified by key to val.
-<!--page 402 indent 4-->
+<!--page 402 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tss_set function returns thrd_success on success or thrd_error if the
request could not be honored.
<a name="7.25.7.1" href="#7.25.7.1"><h5>7.25.7.1 The xtime_get function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.25"><threads.h></a>
int xtime_get(xtime *xt, int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The xtime_get function sets the xtime object pointed to by xt to hold the current
time based on the time base base.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the xtime_get function is successful it returns the nonzero value base, which must
be TIME_UTC; otherwise, it returns zero.<sup><a href="#note306"><b>306)</b></a></sup>
-<!--page 403 indent 4-->
+<!--page 403 -->
<h6>footnotes</h6>
<p><small><a name="note306" href="#note306">306)</a> Although an xtime object describes times with nanosecond resolution, the actual resolution in an
<a name="7.26" href="#7.26"><h3>7.26 Date and time <time.h></h3></a>
<a name="7.26.1" href="#7.26.1"><h4>7.26.1 Components of time</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.26"><time.h></a> defines two macros, and declares several types and functions for
manipulating time. Many functions deal with a calendar time that represents the current
date (according to the Gregorian calendar) and time. Some functions deal with local
time, which is the calendar time expressed for some specific time zone, and with Daylight
Saving Time, which is a temporary change in the algorithm for determining local time.
The local time zone and Daylight Saving Time are implementation-defined.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros defined are NULL (described in <a href="#7.19">7.19</a>); and
<pre>
CLOCKS_PER_SEC</pre>
which expands to an expression with type clock_t (described below) that is the
number per second of the value returned by the clock function.
-<p><!--para 3-->
+<p><!--para 3 -->
The types declared are size_t (described in <a href="#7.19">7.19</a>);
<pre>
clock_t</pre>
<pre>
struct tm</pre>
which holds the components of a calendar time, called the broken-down time.
-<p><!--para 4-->
+<p><!--para 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
-<!--page 404 indent 4-->
+<!--page 404 -->
The value of tm_isdst is positive if Daylight Saving Time is in effect, zero if Daylight
Saving Time is not in effect, and negative if the information is not available.
<a name="7.26.2.1" href="#7.26.2.1"><h5>7.26.2.1 The clock function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
clock_t clock(void);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The clock function determines the processor time used.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The clock function returns the implementation's best approximation to the processor
time used by the program since the beginning of an implementation-defined era related
only to the program invocation. To determine the time in seconds, the value returned by
<a name="7.26.2.2" href="#7.26.2.2"><h5>7.26.2.2 The difftime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
double difftime(time_t time1, time_t time0);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The difftime function computes the difference between two calendar times: time1 -
time0.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The difftime function returns the difference expressed in seconds as a double.
-<!--page 405 indent 4-->
+<!--page 405 -->
<a name="7.26.2.3" href="#7.26.2.3"><h5>7.26.2.3 The mktime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
time_t mktime(struct tm *timeptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mktime function converts the broken-down time, expressed as local time, in the
structure pointed to by timeptr into a calendar time value with the same encoding as
that of the values returned by the time function. The original values of the tm_wday
time, but with their values forced to the ranges indicated above; the final value of
tm_mday is not set until tm_mon and tm_year are determined.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mktime function returns the specified calendar time encoded as a value of type
time_t. If the calendar time cannot be represented, the function returns the value
(time_t)(-1).
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE What day of the week is July 4, 2001?
<pre>
#include <a href="#7.21"><stdio.h></a>
-<!--page 406 indent 4-->
+<!--page 406 -->
<pre>
time_str.tm_year = 2001 - 1900;
time_str.tm_mon = 7 - 1;
<a name="7.26.2.4" href="#7.26.2.4"><h5>7.26.2.4 The time function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
time_t time(time_t *timer);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The time function determines the current calendar time. The encoding of the value is
unspecified.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The time function returns the implementation's best approximation to the current
calendar time. The value (time_t)(-1) is returned if the calendar time is not
available. If timer is not a null pointer, the return value is also assigned to the object it
points to.
<a name="7.26.3" href="#7.26.3"><h4>7.26.3 Time conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Except for the strftime function, these functions each return a pointer to one of two
types of static objects: a broken-down time structure or an array of char. Execution of
any of the functions that return a pointer to one of these object types may overwrite the
<a name="7.26.3.1" href="#7.26.3.1"><h5>7.26.3.1 The asctime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
char *asctime(const struct tm *timeptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The asctime function converts the broken-down time in the structure pointed to by
timeptr into a string in the form
-<!--page 407 indent 4-->
+<!--page 407 -->
<pre>
Sun Sep 16 01:03:52 1973\n\0</pre>
using the equivalent of the following algorithm.
1900 + timeptr->tm_year);
return result;</pre>
}
-<p><!--para 3-->
+<p><!--para 3 -->
If any of the fields of the broken-down time contain values that are outside their normal
ranges,<sup><a href="#note310"><b>310)</b></a></sup> the behavior of the asctime function is undefined. Likewise, if the
calculated year exceeds four digits or is less than the year 1000, the behavior is
undefined.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The asctime function returns a pointer to the string.
<h6>footnotes</h6>
<a name="7.26.3.2" href="#7.26.3.2"><h5>7.26.3.2 The ctime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
char *ctime(const time_t *timer);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ctime function converts the calendar time pointed to by timer to local time in the
form of a string. It is equivalent to
<pre>
-<!--page 408 indent 4-->
+<!--page 408 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The ctime function returns the pointer returned by the asctime function with that
broken-down time as argument.
<p><b> Forward references</b>: the localtime function (<a href="#7.26.3.4">7.26.3.4</a>).
<a name="7.26.3.3" href="#7.26.3.3"><h5>7.26.3.3 The gmtime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
struct tm *gmtime(const time_t *timer);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The gmtime function converts the calendar time pointed to by timer into a broken-
down time, expressed as UTC.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The gmtime function returns a pointer to the broken-down time, or a null pointer if the
specified time cannot be converted to UTC.
<a name="7.26.3.4" href="#7.26.3.4"><h5>7.26.3.4 The localtime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
struct tm *localtime(const time_t *timer);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The localtime function converts the calendar time pointed to by timer into a
broken-down time, expressed as local time.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The localtime function returns a pointer to the broken-down time, or a null pointer if
the specified time cannot be converted to local time.
<a name="7.26.3.5" href="#7.26.3.5"><h5>7.26.3.5 The strftime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
-<!--page 409 indent 4-->
+<p><!--para 1 -->
+<!--page 409 -->
<pre>
#include <a href="#7.26"><time.h></a>
size_t strftime(char * restrict s,
const char * restrict format,
const struct tm * restrict timeptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strftime function places characters into the array pointed to by s as controlled by
the string pointed to by format. The format shall be a multibyte character sequence,
beginning and ending in its initial shift state. The format string consists of zero or
All ordinary multibyte characters (including the terminating null character) are copied
unchanged into the array. If copying takes place between objects that overlap, the
behavior is undefined. No more than maxsize characters are placed into the array.
-<p><!--para 3-->
+<p><!--para 3 -->
Each conversion specifier is replaced by appropriate characters as described in the
following list. The appropriate characters are determined using the LC_TIME category
of the current locale and by the values of zero or more members of the broken-down time
%m is replaced by the month as a decimal number (01-12). [tm_mon]
%M is replaced by the minute as a decimal number (00-59). [tm_min]
%n is replaced by a new-line character.
-<!--page 410 indent 4-->
+<!--page 410 -->
%p is replaced by the locale's equivalent of the AM/PM designations associated with a
<pre>
12-hour clock. [tm_hour]</pre>
<pre>
time zone is determinable. [tm_isdst]</pre>
%% is replaced by %.
-<p><!--para 4-->
+<p><!--para 4 -->
Some conversion specifiers can be modified by the inclusion of an E or O modifier
character to indicate an alternative format or specification. If the alternative format or
specification does not exist for the current locale, the modifier is ignored.
<pre>
representation.</pre>
%EY is replaced by the locale's full alternative year representation.
-<!--page 411 indent 4-->
+<!--page 411 -->
%Od is replaced by the day of the month, using the locale's alternative numeric symbols
<pre>
(filled as needed with leading zeros, or with leading spaces if there is no alternative
<pre>
symbols.</pre>
%Oy is replaced by the last 2 digits of the year, using the locale's alternative numeric
-<p><!--para 5-->
+<p><!--para 5 -->
<pre>
symbols.</pre>
%g, %G, and %V give values according to the ISO 8601 week-based year. In this system,
December 29th, 30th, or 31st is a Monday, it and any following days are part of week 1 of
the following year. Thus, for Tuesday 30th December 1997, %G is replaced by 1998 and
%V is replaced by 01.
-<p><!--para 6-->
+<p><!--para 6 -->
If a conversion specifier is not one of the above, the behavior is undefined.
-<p><!--para 7-->
+<p><!--para 7 -->
In the "C" locale, the E and O modifiers are ignored and the replacement strings for the
following specifiers are:
%a the first three characters of %A.
%b the first three characters of %B.
%B one of ''January'', ''February'', ... , ''December''.
%c equivalent to ''%a %b %e %T %Y''.
-<!--page 412 indent 4-->
+<!--page 412 -->
%p one of ''AM'' or ''PM''.
%r equivalent to ''%I:%M:%S %p''.
%x equivalent to ''%m/%d/%y''.
%X equivalent to %T.
%Z implementation-defined.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
If the total number of resulting characters including the terminating null character is not
more than maxsize, the strftime function returns the number of characters placed
into the array pointed to by s not including the terminating null character. Otherwise,
zero is returned and the contents of the array are indeterminate.
-<!--page 413 indent 4-->
+<!--page 413 -->
<a name="7.27" href="#7.27"><h3>7.27 Unicode utilities <uchar.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.27"><uchar.h></a> declares types and functions for manipulating Unicode
characters.
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are mbstate_t (described in <a href="#7.29.1">7.29.1</a>) and size_t (described in
<a href="#7.19">7.19</a>);
<pre>
uint_least32_t (also described in <a href="#7.20.1.2">7.20.1.2</a>).
<a name="7.27.1" href="#7.27.1"><h4>7.27.1 Restartable multibyte/wide character conversion functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
These functions have a parameter, ps, of type pointer to mbstate_t that points to an
object that can completely describe the current conversion state of the associated
multibyte character sequence, which the functions alter as necessary. If ps is a null
<a name="7.27.1.1" href="#7.27.1.1"><h5>7.27.1.1 The mbrtoc16 function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.27"><uchar.h></a>
size_t mbrtoc16(char16_t * restrict pc16,
const char * restrict s, size_t n,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is a null pointer, the mbrtoc16 function is equivalent to the call:
<pre>
mbrtoc16(NULL, "", 1, ps)</pre>
In this case, the values of the parameters pc16 and n are ignored.
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, the mbrtoc16 function inspects at most n bytes beginning with
the byte pointed to by s to determine the number of bytes needed to complete the next
multibyte character (including any shift sequences). If the function determines that the
next multibyte character is complete and valid, it determines the values of the
corresponding wide characters and then, if pc16 is not a null pointer, stores the value of
the first (or only) such character in the object pointed to by pc16. Subsequent calls will
-<!--page 414 indent 4-->
+<!--page 414 -->
store successive wide characters without consuming any additional input until all the
characters have been stored. If the corresponding wide character is the null wide
character, the resulting state described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The mbrtoc16 function returns the first of the following that applies (given the current
conversion state):
0 if the next n or fewer bytes complete the multibyte character that
<a name="7.27.1.2" href="#7.27.1.2"><h5>7.27.1.2 The c16rtomb function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.27"><uchar.h></a>
size_t c16rtomb(char * restrict s, char16_t c16,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is a null pointer, the c16rtomb function is equivalent to the call
<pre>
c16rtomb(buf, L'\0', ps)</pre>
where buf is an internal buffer.
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, the c16rtomb function determines the number of bytes needed
to represent the multibyte character that corresponds to the wide character given by c16
(including any shift sequences), and stores the multibyte character representation in the
-<!--page 415 indent 4-->
+<!--page 415 -->
array whose first element is pointed to by s. At most MB_CUR_MAX bytes are stored. If
c16 is a null wide character, a null byte is stored, preceded by any shift sequence needed
to restore the initial shift state; the resulting state described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The c16rtomb function returns the number of bytes stored in the array object (including
any shift sequences). When c16 is not a valid wide character, an encoding error occurs:
the function stores the value of the macro EILSEQ in errno and returns
<a name="7.27.1.3" href="#7.27.1.3"><h5>7.27.1.3 The mbrtoc32 function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.27"><uchar.h></a>
size_t mbrtoc32(char32_t * restrict pc32,
const char * restrict s, size_t n,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is a null pointer, the mbrtoc32 function is equivalent to the call:
<pre>
mbrtoc32(NULL, "", 1, ps)</pre>
In this case, the values of the parameters pc32 and n are ignored.
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, the mbrtoc32 function inspects at most n bytes beginning with
the byte pointed to by s to determine the number of bytes needed to complete the next
multibyte character (including any shift sequences). If the function determines that the
characters have been stored. If the corresponding wide character is the null wide
character, the resulting state described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The mbrtoc32 function returns the first of the following that applies (given the current
conversion state):
0 if the next n or fewer bytes complete the multibyte character that
<pre>
corresponds to the null wide character (which is the value stored).</pre>
between 1 and n inclusive if the next n or fewer bytes complete a valid multibyte
-<!--page 416 indent 4-->
+<!--page 416 -->
<pre>
character (which is the value stored); the value returned is the number
of bytes that complete the multibyte character.</pre>
<a name="7.27.1.4" href="#7.27.1.4"><h5>7.27.1.4 The c32rtomb function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.27"><uchar.h></a>
size_t c32rtomb(char * restrict s, char32_t c32,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is a null pointer, the c32rtomb function is equivalent to the call
<pre>
c32rtomb(buf, L'\0', ps)</pre>
where buf is an internal buffer.
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, the c32rtomb function determines the number of bytes needed
to represent the multibyte character that corresponds to the wide character given by c32
(including any shift sequences), and stores the multibyte character representation in the
c32 is a null wide character, a null byte is stored, preceded by any shift sequence needed
to restore the initial shift state; the resulting state described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The c32rtomb function returns the number of bytes stored in the array object (including
any shift sequences). When c32 is not a valid wide character, an encoding error occurs:
the function stores the value of the macro EILSEQ in errno and returns
-<!--page 417 indent 4-->
+<!--page 417 -->
<a name="7.28" href="#7.28"><h3>7.28 Extended multibyte and wide character utilities <wchar.h></h3></a>
<a name="7.28.1" href="#7.28.1"><h4>7.28.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.28"><wchar.h></a> defines four macros, and declares four data types, one tag, and
many functions.<sup><a href="#note313"><b>313)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are wchar_t and size_t (both described in <a href="#7.19">7.19</a>);
<pre>
mbstate_t</pre>
<pre>
struct tm</pre>
which is declared as an incomplete structure type (the contents are described in <a href="#7.26.1">7.26.1</a>).
-<p><!--para 3-->
+<p><!--para 3 -->
The macros defined are NULL (described in <a href="#7.19">7.19</a>); WCHAR_MIN and WCHAR_MAX
(described in <a href="#7.20.3">7.20.3</a>); and
<pre>
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.
-<p><!--para 4-->
+<p><!--para 4 -->
The functions declared are grouped as follows:
<ul>
<li> Functions that perform input and output of wide characters, or multibyte characters,
<li> Functions that perform general wide string manipulation;
-<!--page 418 indent 4-->
+<!--page 418 -->
<li> Functions for wide string date and time conversion; and
<li> Functions that provide extended capabilities for conversion between multibyte and
wide character sequences.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
Unless explicitly stated otherwise, if the execution of a function described in this
subclause causes copying to take place between objects that overlap, the behavior is
undefined.
</small>
<a name="7.28.2" href="#7.28.2"><h4>7.28.2 Formatted wide character input/output functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The formatted wide character input/output functions shall behave as if there is a sequence
point after the actions associated with each specifier.<sup><a href="#note316"><b>316)</b></a></sup>
<a name="7.28.2.1" href="#7.28.2.1"><h5>7.28.2.1 The fwprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
int fwprintf(FILE * restrict stream,
const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fwprintf function writes output to the stream pointed to by stream, under
control of the wide string pointed to by format that specifies how subsequent arguments
are converted for output. If there are insufficient arguments for the format, the behavior
is undefined. If the format is exhausted while arguments remain, the excess arguments
are evaluated (as always) but are otherwise ignored. The fwprintf function returns
when the end of the format string is encountered.
-<p><!--para 3-->
+<p><!--para 3 -->
The format is composed of zero or more directives: ordinary wide characters (not %),
which are copied unchanged to the output stream; and conversion specifications, each of
which results in fetching zero or more subsequent arguments, converting them, if
applicable, according to the corresponding conversion specifier, and then writing the
result to the output stream.
-<p><!--para 4-->
+<p><!--para 4 -->
Each conversion specification is introduced by the wide character %. After the %, the
following appear in sequence:
<ul>
than the field width, it is padded with spaces (by default) on the left (or right, if the
-<!--page 419 indent 4-->
+<!--page 419 -->
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.<sup><a href="#note317"><b>317)</b></a></sup>
<li> A conversion specifier wide character that specifies the type of conversion to be
applied.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
As noted above, a field width, or precision, or both, may be indicated by an asterisk. In
this case, an int argument supplies the field width or precision. The arguments
specifying field width, or precision, or both, shall appear (in that order) before the
argument (if any) to be converted. A negative field width argument is taken as a - flag
followed by a positive field width. A negative precision argument is taken as if the
precision were omitted.
-<p><!--para 6-->
+<p><!--para 6 -->
The flag wide characters and their meanings are:
- The result of the conversion is left-justified within the field. (It is right-justified if
<pre>
conversion, a nonzero result has 0x (or 0X) prefixed to it. For a, A, e, E, f, F, g,</pre>
-<!--page 420 indent 4-->
+<!--page 420 -->
<pre>
and G conversions, the result of converting a floating-point number always
contains a decimal-point wide character, even if no digits follow it. (Normally, a
digit follows it.) For g and G conversions, trailing zeros are not removed from the
result. For other conversions, the behavior is undefined.</pre>
0 For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, leading zeros
-<p><!--para 7-->
+<p><!--para 7 -->
<pre>
(following any indication of sign or base) are used to pad to the field width rather
than performing space padding, except when converting an infinity or NaN. If the
following n conversion specifier applies to a pointer to a long long int
argument.</pre>
j Specifies that a following d, i, o, u, x, or X conversion specifier applies to
-<!--page 421 indent 4-->
+<!--page 421 -->
<pre>
an intmax_t or uintmax_t argument; or that a following n conversion
specifier applies to a pointer to an intmax_t argument.</pre>
applies to a long double argument.</pre>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
-<p><!--para 8-->
+<p><!--para 8 -->
The conversion specifiers and their meanings are:
d,i The int argument is converted to signed decimal in the style [-]dddd. The
<pre>
with leading zeros. The default precision is 1. The result of converting a
zero value with a precision of zero is no wide characters.</pre>
f,F A double argument representing a floating-point number is converted to
-<!--page 422 indent 0-->
+<!--page 422 -->
<pre>
decimal notation in the style [-]ddd.ddd, where the number of digits after
the decimal-point wide character is equal to the precision specification. If the
is missing and FLT_RADIX is a power of 2, then the precision is sufficient</pre>
-<!--page 423 indent 0-->
+<!--page 423 -->
<pre>
for an exact representation of the value; if the precision is missing and
FLT_RADIX is not a power of 2, then the precision is sufficient to
<pre>
converted to a sequence of printing wide characters, in an implementation-</pre>
-<!--page 424 indent 5-->
+<!--page 424 -->
<pre>
defined manner.</pre>
n The argument shall be a pointer to signed integer into which is written the
conversion specification includes any flags, a field width, or a precision, the
behavior is undefined.</pre>
% A % wide character is written. No argument is converted. The complete
-<p><!--para 9-->
+<p><!--para 9 -->
<pre>
conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note322"><b>322)</b></a></sup> If any argument is
not the correct type for the corresponding conversion specification, the behavior is
undefined.
-<p><!--para 10-->
+<p><!--para 10 -->
In no case does a nonexistent or small field width cause truncation of a field; if the result
of a conversion is wider than the field width, the field is expanded to contain the
conversion result.
-<p><!--para 11-->
+<p><!--para 11 -->
For a and A conversions, if FLT_RADIX is a power of 2, the value is correctly rounded
to a hexadecimal floating number with the given precision.
Recommended practice
-<p><!--para 12-->
+<p><!--para 12 -->
For a and A conversions, if FLT_RADIX is not a power of 2 and the result is not exactly
representable in the given precision, the result should be one of the two adjacent numbers
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.
-<p><!--para 13-->
+<p><!--para 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.<sup><a href="#note323"><b>323)</b></a></sup> If the number of
significant decimal digits is more than DECIMAL_DIG but the source value is exactly
of the resultant decimal string D should satisfy L <= D <= U, with the extra stipulation that
the error should have a correct sign for the current rounding direction.
<h6>Returns</h6>
-<p><!--para 14-->
+<p><!--para 14 -->
The fwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
-<!--page 425 indent 5-->
+<!--page 425 -->
Environmental limits
-<p><!--para 15-->
+<p><!--para 15 -->
The number of wide characters that can be produced by any single conversion shall be at
least 4095.
-<p><!--para 16-->
+<p><!--para 16 -->
EXAMPLE To print a date and time in the form ''Sunday, July 3, 10:02'' followed by pi to five decimal
places:
<pre>
<a name="7.28.2.2" href="#7.28.2.2"><h5>7.28.2.2 The fwscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
int fwscanf(FILE * restrict stream,
const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fwscanf function reads input from the stream pointed to by stream, under
control of the wide string pointed to by format that specifies the admissible input
sequences and how they are to be converted for assignment, using subsequent arguments
arguments for the format, the behavior is undefined. If the format is exhausted while
arguments remain, the excess arguments are evaluated (as always) but are otherwise
ignored.
-<p><!--para 3-->
+<p><!--para 3 -->
The format is composed of zero or more directives: one or more white-space wide
characters, an ordinary wide character (neither % nor a white-space wide character), or a
conversion specification. Each conversion specification is introduced by the wide
<li> An optional assignment-suppressing wide character *.
<li> An optional decimal integer greater than zero that specifies the maximum field width
(in wide characters).
-<!--page 426 indent 5-->
+<!--page 426 -->
<li> An optional length modifier that specifies the size of the receiving object.
<li> A conversion specifier wide character that specifies the type of conversion to be
applied.
</ul>
-<p><!--para 4-->
+<p><!--para 4 -->
The fwscanf function executes each directive of the format in turn. When all directives
have been executed, or if a directive fails (as detailed below), the function returns.
Failures are described as input failures (due to the occurrence of an encoding error or the
unavailability of input characters), or matching failures (due to inappropriate input).
-<p><!--para 5-->
+<p><!--para 5 -->
A directive composed of white-space wide character(s) is executed by reading input up to
the first non-white-space wide character (which remains unread), or until no more wide
characters can be read.
-<p><!--para 6-->
+<p><!--para 6 -->
A directive that is an ordinary wide character is executed by reading the next wide
character of the stream. If that wide character differs from the directive, the directive
fails and the differing and subsequent wide characters remain unread. Similarly, if end-
of-file, an encoding error, or a read error prevents a wide character from being read, the
directive fails.
-<p><!--para 7-->
+<p><!--para 7 -->
A directive that is a conversion specification defines a set of matching input sequences, as
described below for each specifier. A conversion specification is executed in the
following steps:
-<p><!--para 8-->
+<p><!--para 8 -->
Input white-space wide characters (as specified by the iswspace function) are skipped,
unless the specification includes a [, c, or n specifier.<sup><a href="#note324"><b>324)</b></a></sup>
-<p><!--para 9-->
+<p><!--para 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
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.
-<p><!--para 10-->
+<p><!--para 10 -->
Except in the case of a % specifier, the input item (or, in the case of a %n directive, the
count of input wide characters) is converted to a type appropriate to the conversion
specifier. If the input item is not a matching sequence, the execution of the directive fails:
following the format argument that has not already received a conversion result. If this
-<!--page 427 indent 5-->
+<!--page 427 -->
object does not have an appropriate type, or if the result of the conversion cannot be
represented in the object, the behavior is undefined.
-<p><!--para 11-->
+<p><!--para 11 -->
The length modifiers and their meanings are:
hh Specifies that a following d, i, o, u, x, X, or n conversion specifier applies
<pre>
applies to an argument with type pointer to long double.</pre>
If a length modifier appears with any conversion specifier other than as specified above,
the behavior is undefined.
-<p><!--para 12-->
+<p><!--para 12 -->
The conversion specifiers and their meanings are:
d Matches an optionally signed decimal integer, whose format is the same as
<pre>
for the base argument. The corresponding argument shall be a pointer to
signed integer.</pre>
i Matches an optionally signed integer, whose format is the same as expected
-<!--page 428 indent 0-->
+<!--page 428 -->
<pre>
for the subject sequence of the wcstol function with the value 0 for the
base argument. The corresponding argument shall be a pointer to signed
pointer to the initial element of an array of wchar_t large enough to accept
the sequence. No null wide character is added.</pre>
s Matches a sequence of non-white-space wide characters.
-<!--page 429 indent 0-->
+<!--page 429 -->
<pre>
If no l length modifier is present, characters from the input field are
converted as if by repeated calls to the wcrtomb function, with the
during the same program execution, the pointer that results shall compare
equal to that value; otherwise the behavior of the %p conversion is undefined.</pre>
n No input is consumed. The corresponding argument shall be a pointer to
-<!--page 430 indent 5-->
+<!--page 430 -->
<pre>
signed integer into which is to be written the number of wide characters read
from the input stream so far by this call to the fwscanf function. Execution
assignment-suppressing wide character or a field width, the behavior is
undefined.</pre>
% Matches a single % wide character; no conversion or assignment occurs. The
-<p><!--para 13-->
+<p><!--para 13 -->
<pre>
complete conversion specification shall be %%.</pre>
If a conversion specification is invalid, the behavior is undefined.<sup><a href="#note326"><b>326)</b></a></sup>
-<p><!--para 14-->
+<p><!--para 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.
-<p><!--para 15-->
+<p><!--para 15 -->
Trailing white space (including new-line wide characters) is left unread unless matched
by a directive. The success of literal matches and suppressed assignments is not directly
determinable other than via the %n directive.
<h6>Returns</h6>
-<p><!--para 16-->
+<p><!--para 16 -->
The fwscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the function returns the
number of input items assigned, which can be fewer than provided for, or even zero, in
the event of an early matching failure.
-<p><!--para 17-->
+<p><!--para 17 -->
EXAMPLE 1 The call:
<pre>
#include <a href="#7.21"><stdio.h></a>
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
-<p><!--para 18-->
+<p><!--para 18 -->
EXAMPLE 2 The call:
<pre>
#include <a href="#7.21"><stdio.h></a>
56.0. The next wide character read from the input stream will be a.
-<!--page 431 indent 4-->
+<!--page 431 -->
<p><b> Forward references</b>: the wcstod, wcstof, and wcstold functions (<a href="#7.28.4.1.1">7.28.4.1.1</a>), the
wcstol, wcstoll, wcstoul, and wcstoull functions (<a href="#7.28.4.1.2">7.28.4.1.2</a>), the wcrtomb
function (<a href="#7.28.6.3.3">7.28.6.3.3</a>).
<a name="7.28.2.3" href="#7.28.2.3"><h5>7.28.2.3 The swprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int swprintf(wchar_t * restrict s,
size_t n,
const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The swprintf function is equivalent to fwprintf, except that the argument s
specifies an array of wide characters into which the generated output is to be written,
rather than written to a stream. No more than n wide characters are written, including a
terminating null wide character, which is always added (unless n is zero).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The swprintf function returns the number of wide characters written in the array, not
counting the terminating null wide character, or a negative value if an encoding error
occurred or if n or more wide characters were requested to be written.
<a name="7.28.2.4" href="#7.28.2.4"><h5>7.28.2.4 The swscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int swscanf(const wchar_t * restrict s,
const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The swscanf function is equivalent to fwscanf, except that the argument s specifies a
wide string from which the input is to be obtained, rather than from a stream. Reaching
the end of the wide string is equivalent to encountering end-of-file for the fwscanf
function.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The swscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the swscanf function
returns the number of input items assigned, which can be fewer than provided for, or even
zero, in the event of an early matching failure.
-<!--page 432 indent 4-->
+<!--page 432 -->
<a name="7.28.2.5" href="#7.28.2.5"><h5>7.28.2.5 The vfwprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vfwprintf function is equivalent to fwprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwprintf function does not invoke the
va_end macro.<sup><a href="#note327"><b>327)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vfwprintf function returns the number of wide characters transmitted, or a
negative value if an output or encoding error occurred.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The following shows the use of the vfwprintf function in a general error-reporting
routine.
<pre>
-<!--page 433 indent 4-->
+<!--page 433 -->
<h6>footnotes</h6>
<p><small><a name="note327" href="#note327">327)</a> As the functions vfwprintf, vswprintf, vfwscanf, vwprintf, vwscanf, and vswscanf
<a name="7.28.2.6" href="#7.28.2.6"><h5>7.28.2.6 The vfwscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.21"><stdio.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vfwscanf function is equivalent to fwscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwscanf function does not invoke the
va_end macro.327)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vfwscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the vfwscanf function
returns the number of input items assigned, which can be fewer than provided for, or even
<a name="7.28.2.7" href="#7.28.2.7"><h5>7.28.2.7 The vswprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.28"><wchar.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vswprintf function is equivalent to swprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswprintf function does not invoke the
va_end macro.327)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vswprintf function returns the number of wide characters written in the array, not
counting the terminating null wide character, or a negative value if an encoding error
occurred or if n or more wide characters were requested to be generated.
-<!--page 434 indent 4-->
+<!--page 434 -->
<a name="7.28.2.8" href="#7.28.2.8"><h5>7.28.2.8 The vswscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.28"><wchar.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vswscanf function is equivalent to swscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswscanf function does not invoke the
va_end macro.327)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vswscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the vswscanf function
returns the number of input items assigned, which can be fewer than provided for, or even
<a name="7.28.2.9" href="#7.28.2.9"><h5>7.28.2.9 The vwprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.28"><wchar.h></a>
int vwprintf(const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vwprintf function is equivalent to wprintf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwprintf function does not invoke the
va_end macro.327)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vwprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
-<!--page 435 indent 4-->
+<!--page 435 -->
<a name="7.28.2.10" href="#7.28.2.10"><h5>7.28.2.10 The vwscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.16"><stdarg.h></a>
#include <a href="#7.28"><wchar.h></a>
int vwscanf(const wchar_t * restrict format,
va_list arg);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The vwscanf function is equivalent to wscanf, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwscanf function does not invoke the
va_end macro.327)
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The vwscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the vwscanf function
returns the number of input items assigned, which can be fewer than provided for, or even
<a name="7.28.2.11" href="#7.28.2.11"><h5>7.28.2.11 The wprintf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int wprintf(const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wprintf function is equivalent to fwprintf with the argument stdout
interposed before the arguments to wprintf.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wprintf function returns the number of wide characters transmitted, or a negative
value if an output or encoding error occurred.
<a name="7.28.2.12" href="#7.28.2.12"><h5>7.28.2.12 The wscanf function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int wscanf(const wchar_t * restrict format, ...);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wscanf function is equivalent to fwscanf with the argument stdin interposed
before the arguments to wscanf.
-<!--page 436 indent 4-->
+<!--page 436 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wscanf function returns the value of the macro EOF if an input failure occurs
before the first conversion (if any) has completed. Otherwise, the wscanf function
returns the number of input items assigned, which can be fewer than provided for, or even
<a name="7.28.3.1" href="#7.28.3.1"><h5>7.28.3.1 The fgetwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
wint_t fgetwc(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If the end-of-file indicator for the input stream pointed to by stream is not set and a
next wide character is present, the fgetwc function obtains that wide character as a
wchar_t converted to a wint_t and advances the associated file position indicator for
the stream (if defined).
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-
of-file indicator for the stream is set and the fgetwc function returns WEOF. Otherwise,
the fgetwc function returns the next wide character from the input stream pointed to by
<a name="7.28.3.2" href="#7.28.3.2"><h5>7.28.3.2 The fgetws function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
wchar_t *fgetws(wchar_t * restrict s,
int n, FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fgetws function reads at most one less than the number of wide characters
specified by n from the stream pointed to by stream into the array pointed to by s. No
-<!--page 437 indent 4-->
+<!--page 437 -->
additional wide characters are read after a new-line wide character (which is retained) or
after end-of-file. A null wide character is written immediately after the last wide
character read into the array.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fgetws function returns s if successful. If end-of-file is encountered and no
characters have been read into the array, the contents of the array remain unchanged and a
null pointer is returned. If a read or encoding error occurs during the operation, the array
<a name="7.28.3.3" href="#7.28.3.3"><h5>7.28.3.3 The fputwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
wint_t fputwc(wchar_t c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fputwc function writes the wide character specified by c to the output stream
pointed to by stream, at the position indicated by the associated file position indicator
for the stream (if defined), and advances the indicator appropriately. If the file cannot
support positioning requests, or if the stream was opened with append mode, the
character is appended to the output stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fputwc function returns the wide character written. If a write error occurs, the
error indicator for the stream is set and fputwc returns WEOF. If an encoding error
occurs, the value of the macro EILSEQ is stored in errno and fputwc returns WEOF.
<a name="7.28.3.4" href="#7.28.3.4"><h5>7.28.3.4 The fputws function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
int fputws(const wchar_t * restrict s,
FILE * restrict stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fputws function writes the wide string pointed to by s to the stream pointed to by
stream. The terminating null wide character is not written.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fputws function returns EOF if a write or encoding error occurs; otherwise, it
returns a nonnegative value.
-<!--page 438 indent 4-->
+<!--page 438 -->
<a name="7.28.3.5" href="#7.28.3.5"><h5>7.28.3.5 The fwide function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
int fwide(FILE *stream, int mode);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The fwide function determines the orientation of the stream pointed to by stream. If
mode is greater than zero, the function first attempts to make the stream wide oriented. If
mode is less than zero, the function first attempts to make the stream byte oriented.<sup><a href="#note329"><b>329)</b></a></sup>
Otherwise, mode is zero and the function does not alter the orientation of the stream.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The fwide function returns a value greater than zero if, after the call, the stream has
wide orientation, a value less than zero if the stream has byte orientation, or zero if the
stream has no orientation.
<a name="7.28.3.6" href="#7.28.3.6"><h5>7.28.3.6 The getwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
wint_t getwc(FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getwc function is equivalent to fgetwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so the argument should never be an
expression with side effects.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The getwc function returns the next wide character from the input stream pointed to by
stream, or WEOF.
<a name="7.28.3.7" href="#7.28.3.7"><h5>7.28.3.7 The getwchar function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wint_t getwchar(void);</pre>
-<!--page 439 indent 4-->
+<!--page 439 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The getwchar function is equivalent to getwc with the argument stdin.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The getwchar function returns the next wide character from the input stream pointed to
by stdin, or WEOF.
<a name="7.28.3.8" href="#7.28.3.8"><h5>7.28.3.8 The putwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
wint_t putwc(wchar_t c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The putwc function is equivalent to fputwc, except that if it is implemented as a
macro, it may evaluate stream more than once, so that argument should never be an
expression with side effects.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The putwc function returns the wide character written, or WEOF.
<a name="7.28.3.9" href="#7.28.3.9"><h5>7.28.3.9 The putwchar function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wint_t putwchar(wchar_t c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The putwchar function is equivalent to putwc with the second argument stdout.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The putwchar function returns the character written, or WEOF.
<a name="7.28.3.10" href="#7.28.3.10"><h5>7.28.3.10 The ungetwc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.21"><stdio.h></a>
#include <a href="#7.28"><wchar.h></a>
wint_t ungetwc(wint_t c, FILE *stream);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The ungetwc function pushes the wide character specified by c back onto the input
stream pointed to by stream. Pushed-back wide characters will be returned by
subsequent reads on that stream in the reverse order of their pushing. A successful
-<!--page 440 indent 4-->
+<!--page 440 -->
intervening call (with the stream pointed to by stream) to a file positioning function
(fseek, fsetpos, or rewind) discards any pushed-back wide characters for the
stream. The external storage corresponding to the stream is unchanged.
-<p><!--para 3-->
+<p><!--para 3 -->
One wide character of pushback is guaranteed, even if the call to the ungetwc function
follows just after a call to a formatted wide character input function fwscanf,
vfwscanf, vwscanf, or wscanf. If the ungetwc function is called too many times
on the same stream without an intervening read or file positioning operation on that
stream, the operation may fail.
-<p><!--para 4-->
+<p><!--para 4 -->
If the value of c equals that of the macro WEOF, the operation fails and the input stream is
unchanged.
-<p><!--para 5-->
+<p><!--para 5 -->
A successful call to the ungetwc function clears the end-of-file indicator for the stream.
The value of the file position indicator for the stream after reading or discarding all
pushed-back wide characters is the same as it was before the wide characters were pushed
call to the ungetwc function is unspecified until all pushed-back wide characters are
read or discarded.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The ungetwc function returns the wide character pushed back, or WEOF if the operation
fails.
<a name="7.28.4" href="#7.28.4"><h4>7.28.4 General wide string utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.28"><wchar.h></a> declares a number of functions useful for wide string
manipulation. Various methods are used for determining the lengths of the arrays, but in
all cases a wchar_t * argument points to the initial (lowest addressed) element of the
array. If an array is accessed beyond the end of an object, the behavior is undefined.
-<p><!--para 2-->
+<p><!--para 2 -->
Where an argument declared as size_t n determines the length of the array for a
function, n can have the value zero on a call to that function. Unless explicitly stated
otherwise in the description of a particular function in this subclause, pointer arguments
function that locates a wide character finds no occurrence, a function that compares two
wide character sequences returns zero, and a function that copies wide characters copies
zero wide characters.
-<!--page 441 indent 4-->
+<!--page 441 -->
<a name="7.28.4.1" href="#7.28.4.1"><h5>7.28.4.1 Wide string numeric conversion functions</h5></a>
<a name="7.28.4.1.1" href="#7.28.4.1.1"><h5>7.28.4.1.1 The wcstod, wcstof, and wcstold functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
double wcstod(const wchar_t * restrict nptr,
long double wcstold(const wchar_t * restrict nptr,
wchar_t ** restrict endptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcstod, wcstof, and wcstold functions convert the initial portion of the wide
string pointed to by nptr to double, float, and long double representation,
respectively. First, they decompose the input string into three parts: an initial, possibly
infinity or NaN; and a final wide string of one or more unrecognized wide characters,
including the terminating null wide character of the input wide string. Then, they attempt
to convert the subject sequence to a floating-point number, and return the result.
-<p><!--para 3-->
+<p><!--para 3 -->
The expected form of the subject sequence is an optional plus or minus sign, then one of
the following:
<ul>
</ul>
The subject sequence is defined as the longest initial subsequence of the input wide
string, starting with the first non-white-space wide character, that is of the expected form.
-<!--page 442 indent 4-->
+<!--page 442 -->
The subject sequence contains no wide characters if the input wide string is not of the
expected form.
-<p><!--para 4-->
+<p><!--para 4 -->
If the subject sequence has the expected form for a floating-point number, the sequence of
wide characters starting with the first digit or the decimal-point wide character
(whichever occurs first) is interpreted as a floating constant according to the rules of
the meaning of the n-wchar sequences is implementation-defined.<sup><a href="#note331"><b>331)</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.
-<p><!--para 5-->
+<p><!--para 5 -->
If the subject sequence has the hexadecimal form and FLT_RADIX is a power of 2, the
value resulting from the conversion is correctly rounded.
-<p><!--para 6-->
+<p><!--para 6 -->
In other than the "C" locale, additional locale-specific subject sequence forms may be
accepted.
-<p><!--para 7-->
+<p><!--para 7 -->
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
Recommended practice
-<p><!--para 8-->
+<p><!--para 8 -->
If the subject sequence has the hexadecimal form, FLT_RADIX is not a power of 2, and
the result is not exactly representable, the result should be one of the two numbers in the
appropriate internal format that are adjacent to the hexadecimal floating source value,
-<!--page 443 indent 5-->
-<p><!--para 9-->
+<!--page 443 -->
+<p><!--para 9 -->
If the subject sequence has the decimal form and at most DECIMAL_DIG (defined in
<a href="#7.7"><float.h></a>) significant digits, the result should be correctly rounded. If the subject
sequence D has the decimal form and more than DECIMAL_DIG significant digits,
stipulation that the error with respect to D should have a correct sign for the current
rounding direction.<sup><a href="#note332"><b>332)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
The functions return the converted value, if any. If no conversion could be performed,
zero is returned. If the correct value overflows and default rounding is in effect (<a href="#7.12.1">7.12.1</a>),
plus or minus HUGE_VAL, HUGE_VALF, or HUGE_VALL is returned (according to the
-<!--page 444 indent 4-->
+<!--page 444 -->
<h6>footnotes</h6>
<p><small><a name="note330" href="#note330">330)</a> It is unspecified whether a minus-signed sequence is converted to a negative number directly or by
<a name="7.28.4.1.2" href="#7.28.4.1.2"><h5>7.28.4.1.2 The wcstol, wcstoll, wcstoul, and wcstoull functions</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
long int wcstol(
wchar_t ** restrict endptr,
int base);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcstol, wcstoll, wcstoul, and wcstoull functions convert the initial
portion of the wide string pointed to by nptr to long int, long long int,
unsigned long int, and unsigned long long int representation,
by the value of base, and a final wide string of one or more unrecognized wide
characters, including the terminating null wide character of the input wide string. Then,
they attempt to convert the subject sequence to an integer, and return the result.
-<p><!--para 3-->
+<p><!--para 3 -->
If the value of base is zero, the expected form of the subject sequence is that of an
integer constant as described for the corresponding single-byte characters in <a href="#6.4.4.1">6.4.4.1</a>,
optionally preceded by a plus or minus sign, but not including an integer suffix. If the
letters and digits whose ascribed values are less than that of base are permitted. If the
value of base is 16, the wide characters 0x or 0X may optionally precede the sequence
of letters and digits, following the sign if present.
-<!--page 445 indent 4-->
-<p><!--para 4-->
+<!--page 445 -->
+<p><!--para 4 -->
The subject sequence is defined as the longest initial subsequence of the input wide
string, starting with the first non-white-space wide character, that is of the expected form.
The subject sequence contains no wide characters if the input wide string is empty or
consists entirely of white space, or if the first non-white-space wide character is other
than a sign or a permissible letter or digit.
-<p><!--para 5-->
+<p><!--para 5 -->
If the subject sequence has the expected form and the value of base is zero, the sequence
of wide characters starting with the first digit is interpreted as an integer constant
according to the rules of <a href="#6.4.4.1">6.4.4.1</a>. If the subject sequence has the expected form and the
resulting from the conversion is negated (in the return type). A pointer to the final wide
string is stored in the object pointed to by endptr, provided that endptr is not a null
pointer.
-<p><!--para 6-->
+<p><!--para 6 -->
In other than the "C" locale, additional locale-specific subject sequence forms may be
accepted.
-<p><!--para 7-->
+<p><!--para 7 -->
If the subject sequence is empty or does not have the expected form, no conversion is
performed; the value of nptr is stored in the object pointed to by endptr, provided
that endptr is not a null pointer.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The wcstol, wcstoll, wcstoul, and wcstoull functions return the converted
value, if any. If no conversion could be performed, zero is returned. If the correct value
is outside the range of representable values, LONG_MIN, LONG_MAX, LLONG_MIN,
<a name="7.28.4.2.1" href="#7.28.4.2.1"><h5>7.28.4.2.1 The wcscpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcscpy(wchar_t * restrict s1,
const wchar_t * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscpy function copies the wide string pointed to by s2 (including the terminating
null wide character) into the array pointed to by s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscpy function returns the value of s1.
-<!--page 446 indent 4-->
+<!--page 446 -->
<a name="7.28.4.2.2" href="#7.28.4.2.2"><h5>7.28.4.2.2 The wcsncpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcsncpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsncpy function copies not more than n wide characters (those that follow a null
wide character are not copied) from the array pointed to by s2 to the array pointed to by
s1.<sup><a href="#note333"><b>333)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The wcsncpy function returns the value of s1.
<h6>footnotes</h6>
<a name="7.28.4.2.3" href="#7.28.4.2.3"><h5>7.28.4.2.3 The wmemcpy function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wmemcpy(wchar_t * restrict s1,
const wchar_t * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemcpy function copies n wide characters from the object pointed to by s2 to the
object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemcpy function returns the value of s1.
-<!--page 447 indent 4-->
+<!--page 447 -->
<a name="7.28.4.2.4" href="#7.28.4.2.4"><h5>7.28.4.2.4 The wmemmove function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wmemmove(wchar_t *s1, const wchar_t *s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemmove function copies n wide characters from the object pointed to by s2 to
the object pointed to by s1. Copying takes place as if the n wide characters from the
object pointed to by s2 are first copied into a temporary array of n wide characters that
does not overlap the objects pointed to by s1 or s2, and then the n wide characters from
the temporary array are copied into the object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemmove function returns the value of s1.
<a name="7.28.4.3" href="#7.28.4.3"><h5>7.28.4.3 Wide string concatenation functions</h5></a>
<a name="7.28.4.3.1" href="#7.28.4.3.1"><h5>7.28.4.3.1 The wcscat function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcscat(wchar_t * restrict s1,
const wchar_t * restrict s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscat function appends a copy of the wide string pointed to by s2 (including the
terminating null wide character) to the end of the wide string pointed to by s1. The initial
wide character of s2 overwrites the null wide character at the end of s1.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscat function returns the value of s1.
<a name="7.28.4.3.2" href="#7.28.4.3.2"><h5>7.28.4.3.2 The wcsncat function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcsncat(wchar_t * restrict s1,
const wchar_t * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsncat function appends not more than n wide characters (a null wide character
and those that follow it are not appended) from the array pointed to by s2 to the end of
-<!--page 448 indent 4-->
+<!--page 448 -->
the wide string pointed to by s1. The initial wide character of s2 overwrites the null
wide character at the end of s1. A terminating null wide character is always appended to
the result.<sup><a href="#note334"><b>334)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsncat function returns the value of s1.
<h6>footnotes</h6>
</small>
<a name="7.28.4.4" href="#7.28.4.4"><h5>7.28.4.4 Wide string comparison functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Unless explicitly stated otherwise, the functions described in this subclause order two
wide characters the same way as two integers of the underlying integer type designated
by wchar_t.
<a name="7.28.4.4.1" href="#7.28.4.4.1"><h5>7.28.4.4.1 The wcscmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int wcscmp(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscmp function compares the wide string pointed to by s1 to the wide string
pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscmp function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
wide string pointed to by s2.
<a name="7.28.4.4.2" href="#7.28.4.4.2"><h5>7.28.4.4.2 The wcscoll function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int wcscoll(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscoll function compares the wide string pointed to by s1 to the wide string
pointed to by s2, both interpreted as appropriate to the LC_COLLATE category of the
current locale.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscoll function returns an integer greater than, equal to, or less than zero,
accordingly as the wide string pointed to by s1 is greater than, equal to, or less than the
-<!--page 449 indent 4-->
+<!--page 449 -->
wide string pointed to by s2 when both are interpreted as appropriate to the current
locale.
<a name="7.28.4.4.3" href="#7.28.4.4.3"><h5>7.28.4.4.3 The wcsncmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int wcsncmp(const wchar_t *s1, const wchar_t *s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsncmp function compares not more than n wide characters (those that follow a
null wide character are not compared) from the array pointed to by s1 to the array
pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsncmp function returns an integer greater than, equal to, or less than zero,
accordingly as the possibly null-terminated array pointed to by s1 is greater than, equal
to, or less than the possibly null-terminated array pointed to by s2.
<a name="7.28.4.4.4" href="#7.28.4.4.4"><h5>7.28.4.4.4 The wcsxfrm function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t wcsxfrm(wchar_t * restrict s1,
const wchar_t * restrict s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsxfrm function transforms the wide string pointed to by s2 and places the
resulting wide string into the array pointed to by s1. The transformation is such that if
the wcscmp function is applied to two transformed wide strings, it returns a value greater
into the resulting array pointed to by s1, including the terminating null wide character. If
n is zero, s1 is permitted to be a null pointer.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsxfrm function returns the length of the transformed wide string (not including
the terminating null wide character). If the value returned is n or greater, the contents of
the array pointed to by s1 are indeterminate.
-<p><!--para 4-->
+<p><!--para 4 -->
EXAMPLE The value of the following expression is the length of the array needed to hold the
transformation of the wide string pointed to by s:
-<!--page 450 indent 4-->
+<!--page 450 -->
<pre>
1 + wcsxfrm(NULL, s, 0)</pre>
<a name="7.28.4.4.5" href="#7.28.4.4.5"><h5>7.28.4.4.5 The wmemcmp function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int wmemcmp(const wchar_t *s1, const wchar_t *s2,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemcmp function compares the first n wide characters of the object pointed to by
s1 to the first n wide characters of the object pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemcmp function returns an integer greater than, equal to, or less than zero,
accordingly as the object pointed to by s1 is greater than, equal to, or less than the object
pointed to by s2.
<a name="7.28.4.5.1" href="#7.28.4.5.1"><h5>7.28.4.5.1 The wcschr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcschr(const wchar_t *s, wchar_t c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcschr function locates the first occurrence of c in the wide string pointed to by s.
The terminating null wide character is considered to be part of the wide string.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcschr function returns a pointer to the located wide character, or a null pointer if
the wide character does not occur in the wide string.
<a name="7.28.4.5.2" href="#7.28.4.5.2"><h5>7.28.4.5.2 The wcscspn function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t wcscspn(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcscspn function computes the length of the maximum initial segment of the wide
string pointed to by s1 which consists entirely of wide characters not from the wide
string pointed to by s2.
-<!--page 451 indent 4-->
+<!--page 451 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcscspn function returns the length of the segment.
<a name="7.28.4.5.3" href="#7.28.4.5.3"><h5>7.28.4.5.3 The wcspbrk function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcspbrk(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcspbrk function locates the first occurrence in the wide string pointed to by s1 of
any wide character from the wide string pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcspbrk function returns a pointer to the wide character in s1, or a null pointer if
no wide character from s2 occurs in s1.
<a name="7.28.4.5.4" href="#7.28.4.5.4"><h5>7.28.4.5.4 The wcsrchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcsrchr(const wchar_t *s, wchar_t c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsrchr function locates the last occurrence of c in the wide string pointed to by
s. The terminating null wide character is considered to be part of the wide string.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsrchr function returns a pointer to the wide character, or a null pointer if c does
not occur in the wide string.
<a name="7.28.4.5.5" href="#7.28.4.5.5"><h5>7.28.4.5.5 The wcsspn function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t wcsspn(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsspn function computes the length of the maximum initial segment of the wide
string pointed to by s1 which consists entirely of wide characters from the wide string
pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsspn function returns the length of the segment.
-<!--page 452 indent 4-->
+<!--page 452 -->
<a name="7.28.4.5.6" href="#7.28.4.5.6"><h5>7.28.4.5.6 The wcsstr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcsstr(const wchar_t *s1, const wchar_t *s2);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsstr function locates the first occurrence in the wide string pointed to by s1 of
the sequence of wide characters (excluding the terminating null wide character) in the
wide string pointed to by s2.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcsstr function returns a pointer to the located wide string, or a null pointer if the
wide string is not found. If s2 points to a wide string with zero length, the function
returns s1.
<a name="7.28.4.5.7" href="#7.28.4.5.7"><h5>7.28.4.5.7 The wcstok function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wcstok(wchar_t * restrict s1,
const wchar_t * restrict s2,
wchar_t ** restrict ptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A sequence of calls to the wcstok function breaks the wide string pointed to by s1 into
a sequence of tokens, each of which is delimited by a wide character from the wide string
pointed to by s2. The third argument points to a caller-provided wchar_t pointer into
which the wcstok function stores information necessary for it to continue scanning the
same wide string.
-<p><!--para 3-->
+<p><!--para 3 -->
The first call in a sequence has a non-null first argument and stores an initial value in the
object pointed to by ptr. Subsequent calls in the sequence have a null first argument and
the object pointed to by ptr is required to have the value stored by the previous call in
the sequence, which is then updated. The separator wide string pointed to by s2 may be
different from call to call.
-<p><!--para 4-->
+<p><!--para 4 -->
The first call in the sequence searches the wide string pointed to by s1 for the first wide
character that is not contained in the current separator wide string pointed to by s2. If no
such wide character is found, then there are no tokens in the wide string pointed to by s1
and the wcstok function returns a null pointer. If such a wide character is found, it is
the start of the first token.
-<p><!--para 5-->
+<p><!--para 5 -->
The wcstok function then searches from there for a wide character that is contained in
the current separator wide string. If no such wide character is found, the current token
-<!--page 453 indent 4-->
+<!--page 453 -->
extends to the end of the wide string pointed to by s1, and subsequent searches in the
same wide string for a token return a null pointer. If such a wide character is found, it is
overwritten by a null wide character, which terminates the current token.
-<p><!--para 6-->
+<p><!--para 6 -->
In all cases, the wcstok function stores sufficient information in the pointer pointed to
by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer
value for ptr, shall start searching just past the element overwritten by a null wide
character (if any).
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The wcstok function returns a pointer to the first wide character of a token, or a null
pointer if there is no token.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE
<pre>
#include <a href="#7.28"><wchar.h></a>
<a name="7.28.4.5.8" href="#7.28.4.5.8"><h5>7.28.4.5.8 The wmemchr function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wmemchr(const wchar_t *s, wchar_t c,
size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemchr function locates the first occurrence of c in the initial n wide characters of
the object pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemchr function returns a pointer to the located wide character, or a null pointer if
the wide character does not occur in the object.
-<!--page 454 indent 4-->
+<!--page 454 -->
<a name="7.28.4.6" href="#7.28.4.6"><h5>7.28.4.6 Miscellaneous functions</h5></a>
<a name="7.28.4.6.1" href="#7.28.4.6.1"><h5>7.28.4.6.1 The wcslen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t wcslen(const wchar_t *s);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcslen function computes the length of the wide string pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wcslen function returns the number of wide characters that precede the terminating
null wide character.
<a name="7.28.4.6.2" href="#7.28.4.6.2"><h5>7.28.4.6.2 The wmemset function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wmemset function copies the value of c into each of the first n wide characters of
the object pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wmemset function returns the value of s.
<a name="7.28.5" href="#7.28.5"><h4>7.28.5 Wide character time conversion functions</h4></a>
<a name="7.28.5.1" href="#7.28.5.1"><h5>7.28.5.1 The wcsftime function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.26"><time.h></a>
#include <a href="#7.28"><wchar.h></a>
const wchar_t * restrict format,
const struct tm * restrict timeptr);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsftime function is equivalent to the strftime function, except that:
<ul>
<li> The argument s points to the initial element of an array of wide characters into which
the generated output is to be placed.
-<!--page 455 indent 4-->
+<!--page 455 -->
<li> The argument maxsize indicates the limiting number of wide characters.
<li> The argument format is a wide string and the conversion specifiers are replaced by
corresponding sequences of wide characters.
<li> The return value indicates the number of wide characters.
</ul>
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the total number of resulting wide characters including the terminating null wide
character is not more than maxsize, the wcsftime function returns the number of
wide characters placed into the array pointed to by s not including the terminating null
indeterminate.
<a name="7.28.6" href="#7.28.6"><h4>7.28.6 Extended multibyte/wide character conversion utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.28"><wchar.h></a> declares an extended set of functions useful for conversion
between multibyte characters and wide characters.
-<p><!--para 2-->
+<p><!--para 2 -->
Most of the following functions -- those that are listed as ''restartable'', <a href="#7.28.6.3">7.28.6.3</a> and
<a href="#7.28.6.4">7.28.6.4</a> -- take as a last argument a pointer to an object of type mbstate_t that is used
to describe the current conversion state from a particular multibyte character sequence to
a wide character sequence (or the reverse) under the rules of a particular setting for the
LC_CTYPE category of the current locale.
-<p><!--para 3-->
+<p><!--para 3 -->
The initial conversion state corresponds, for a conversion in either direction, to the
beginning of a new multibyte character in the initial shift state. A zero-valued
mbstate_t object is (at least) one way to describe an initial conversion state. A zero-
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.<sup><a href="#note335"><b>335)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 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 referenced object is
altered as needed to track the shift state, and the position within a multibyte character, for
-<!--page 456 indent 4-->
+<!--page 456 -->
<h6>footnotes</h6>
<p><small><a name="note335" href="#note335">335)</a> Thus, a particular mbstate_t object can be used, for example, with both the mbrtowc and
<a name="7.28.6.1.1" href="#7.28.6.1.1"><h5>7.28.6.1.1 The btowc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a> *
wint_t btowc(int c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The btowc function determines whether c constitutes a valid single-byte character in the
initial shift state.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The btowc function returns WEOF if c has the value EOF or if (unsigned char)c
does not constitute a valid single-byte character in the initial shift state. Otherwise, it
returns the wide character representation of that character.
<a name="7.28.6.1.2" href="#7.28.6.1.2"><h5>7.28.6.1.2 The wctob function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a> *
int wctob(wint_t c);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wctob function determines whether c corresponds to a member of the extended
character set whose multibyte character representation is a single byte when in the initial
shift state.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The wctob function returns EOF if c does not correspond to a multibyte character with
length one in the initial shift state. Otherwise, it returns the single-byte representation of
that character as an unsigned char converted to an int.
<a name="7.28.6.2.1" href="#7.28.6.2.1"><h5>7.28.6.2.1 The mbsinit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
int mbsinit(const mbstate_t *ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If ps is not a null pointer, the mbsinit function determines whether the referenced
mbstate_t object describes an initial conversion state.
-<!--page 457 indent 4-->
+<!--page 457 -->
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mbsinit function returns nonzero if ps is a null pointer or if the referenced object
describes an initial conversion state; otherwise, it returns zero.
<a name="7.28.6.3" href="#7.28.6.3"><h5>7.28.6.3 Restartable multibyte/wide character conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
These functions differ from the corresponding multibyte character functions of <a href="#7.22.7">7.22.7</a>
(mblen, mbtowc, and wctomb) in that they have an extra parameter, ps, of type
pointer to mbstate_t that points to an object that can completely describe the current
program startup to the initial conversion state; the functions are not required to avoid data
races in this case. The implementation behaves as if no library function calls these
functions with a null pointer for ps.
-<p><!--para 2-->
+<p><!--para 2 -->
Also unlike their corresponding functions, the return value does not represent whether the
encoding is state-dependent.
<a name="7.28.6.3.1" href="#7.28.6.3.1"><h5>7.28.6.3.1 The mbrlen function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t mbrlen(const char * restrict s,
size_t n,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mbrlen function is equivalent to the call:
<pre>
mbrtowc(NULL, s, n, ps != NULL ? ps : &internal)</pre>
where internal is the mbstate_t object for the mbrlen function, except that the
expression designated by ps is evaluated only once.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The mbrlen function returns a value between zero and n, inclusive, (size_t)(-2),
or (size_t)(-1).
<p><b> Forward references</b>: the mbrtowc function (<a href="#7.28.6.3.2">7.28.6.3.2</a>).
-<!--page 458 indent 4-->
+<!--page 458 -->
<a name="7.28.6.3.2" href="#7.28.6.3.2"><h5>7.28.6.3.2 The mbrtowc function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t mbrtowc(wchar_t * restrict pwc,
size_t n,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is a null pointer, the mbrtowc function is equivalent to the call:
<pre>
mbrtowc(NULL, "", 1, ps)</pre>
In this case, the values of the parameters pwc and n are ignored.
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, the mbrtowc function inspects at most n bytes beginning with
the byte pointed to by s to determine the number of bytes needed to complete the next
multibyte character (including any shift sequences). If the function determines that the
the object pointed to by pwc. If the corresponding wide character is the null wide
character, the resulting state described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The mbrtowc function returns the first of the following that applies (given the current
conversion state):
0 if the next n or fewer bytes complete the multibyte character that
value is stored); the value of the macro EILSEQ is stored in errno,
and the conversion state is unspecified.</pre>
-<!--page 459 indent 4-->
+<!--page 459 -->
<h6>footnotes</h6>
<p><small><a name="note336" href="#note336">336)</a> When n has at least the value of the MB_CUR_MAX macro, this case can only occur if s points at a
<a name="7.28.6.3.3" href="#7.28.6.3.3"><h5>7.28.6.3.3 The wcrtomb function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t wcrtomb(char * restrict s,
wchar_t wc,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
If s is a null pointer, the wcrtomb function is equivalent to the call
<pre>
wcrtomb(buf, L'\0', ps)</pre>
where buf is an internal buffer.
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, the wcrtomb function determines the number of bytes needed
to represent the multibyte character that corresponds to the wide character given by wc
(including any shift sequences), and stores the multibyte character representation in the
wc is a null wide character, a null byte is stored, preceded by any shift sequence needed
to restore the initial shift state; the resulting state described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The wcrtomb function returns the number of bytes stored in the array object (including
any shift sequences). When wc is not a valid wide character, an encoding error occurs:
the function stores the value of the macro EILSEQ in errno and returns
(size_t)(-1); the conversion state is unspecified.
<a name="7.28.6.4" href="#7.28.6.4"><h5>7.28.6.4 Restartable multibyte/wide string conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
These functions differ from the corresponding multibyte string functions of <a href="#7.22.8">7.22.8</a>
(mbstowcs and wcstombs) in that they have an extra parameter, ps, of type pointer to
mbstate_t that points to an object that can completely describe the current conversion
to the initial conversion state; the functions are not required to avoid data races in this
case. The implementation behaves as if no library function calls these functions with a
null pointer for ps.
-<p><!--para 2-->
+<p><!--para 2 -->
Also unlike their corresponding functions, the conversion source parameter, src, has a
pointer-to-pointer type. When the function is storing the results of conversions (that is,
when dst is not a null pointer), the pointer object pointed to by this parameter is updated
to reflect the amount of the source processed by that invocation.
-<!--page 460 indent 4-->
+<!--page 460 -->
<a name="7.28.6.4.1" href="#7.28.6.4.1"><h5>7.28.6.4.1 The mbsrtowcs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t mbsrtowcs(wchar_t * restrict dst,
size_t len,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The mbsrtowcs function converts a sequence of multibyte characters that begins in the
conversion state described by the object pointed to by ps, from the array indirectly
pointed to by src into a sequence of corresponding wide characters. If dst is not a null
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.<sup><a href="#note337"><b>337)</b></a></sup> Each conversion takes
place as if by a call to the mbrtowc function.
-<p><!--para 3-->
+<p><!--para 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
just past the last multibyte character converted (if any). If conversion stopped due to
reaching a terminating null character and if dst is not a null pointer, the resulting state
described is the initial conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If the input conversion encounters a sequence of bytes that do not form a valid multibyte
character, an encoding error occurs: the mbsrtowcs function stores the value of the
macro EILSEQ in errno and returns (size_t)(-1); the conversion state is
-<!--page 461 indent 4-->
+<!--page 461 -->
<h6>footnotes</h6>
<p><small><a name="note337" href="#note337">337)</a> Thus, the value of len is ignored if dst is a null pointer.
<a name="7.28.6.4.2" href="#7.28.6.4.2"><h5>7.28.6.4.2 The wcsrtombs function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
size_t wcsrtombs(char * restrict dst,
size_t len,
mbstate_t * restrict ps);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsrtombs function converts a sequence of wide characters from the array
indirectly pointed to by src into a sequence of corresponding multibyte characters that
begins in the conversion state described by the object pointed to by ps. If dst is not a
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.<sup><a href="#note338"><b>338)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 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
reaching a terminating null wide character, the resulting state described is the initial
conversion state.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If conversion stops because a wide character is reached that does not correspond to a
valid multibyte character, an encoding error occurs: the wcsrtombs function stores the
value of the macro EILSEQ in errno and returns (size_t)(-1); the conversion
-<!--page 462 indent 4-->
+<!--page 462 -->
<h6>footnotes</h6>
<p><small><a name="note338" href="#note338">338)</a> If conversion stops because a terminating null wide character has been reached, the bytes stored
<a name="7.29" href="#7.29"><h3>7.29 Wide character classification and mapping utilities <wctype.h></h3></a>
<a name="7.29.1" href="#7.29.1"><h4>7.29.1 Introduction</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.29"><wctype.h></a> defines one macro, and declares three data types and many
functions.<sup><a href="#note339"><b>339)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
The types declared are
<pre>
wint_t</pre>
wctype_t</pre>
which is a scalar type that can hold values which represent locale-specific character
classifications.
-<p><!--para 3-->
+<p><!--para 3 -->
The macro defined is WEOF (described in <a href="#7.28.1">7.28.1</a>).
-<p><!--para 4-->
+<p><!--para 4 -->
The functions declared are grouped as follows:
<ul>
<li> Functions that provide wide character classification;
<li> Functions that provide wide character case mapping;
<li> Extensible functions that provide wide character mapping.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
For all functions described in this subclause that accept an argument of type wint_t, the
value shall be representable as a wchar_t or shall equal the value of the macro WEOF. If
this argument has any other value, the behavior is undefined.
-<p><!--para 6-->
+<p><!--para 6 -->
The behavior of these functions is affected by the LC_CTYPE category of the current
locale.
-<!--page 463 indent 4-->
+<!--page 463 -->
<h6>footnotes</h6>
<p><small><a name="note339" href="#note339">339)</a> See ''future library directions'' (<a href="#7.30.13">7.30.13</a>).
</small>
<a name="7.29.2" href="#7.29.2"><h4>7.29.2 Wide character classification utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.29"><wctype.h></a> declares several functions useful for classifying wide
characters.
-<p><!--para 2-->
+<p><!--para 2 -->
The term printing wide character refers to a member of a locale-specific set of wide
characters, each of which occupies at least one printing position on a display device. The
term control wide character refers to a member of a locale-specific set of wide characters
that are not printing wide characters.
<a name="7.29.2.1" href="#7.29.2.1"><h5>7.29.2.1 Wide character classification functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions in this subclause return nonzero (true) if and only if the value of the
argument wc conforms to that in the description of the function.
-<p><!--para 2-->
+<p><!--para 2 -->
Each of the following functions returns true for each wide character that corresponds (as
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
<a name="7.29.2.1.1" href="#7.29.2.1.1"><h5>7.29.2.1.1 The iswalnum function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswalnum(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswalnum function tests for any wide character for which iswalpha or
iswdigit is true.
<a name="7.29.2.1.2" href="#7.29.2.1.2"><h5>7.29.2.1.2 The iswalpha function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswalpha(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswalpha function tests for any wide character for which iswupper or
iswlower is true, or any wide character that is one of a locale-specific set of alphabetic
-<!--page 464 indent 4-->
+<!--page 464 -->
wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace
is true.<sup><a href="#note341"><b>341)</b></a></sup>
<a name="7.29.2.1.3" href="#7.29.2.1.3"><h5>7.29.2.1.3 The iswblank function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswblank(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswblank function tests for any wide character that is a standard blank wide
character or is one of a locale-specific set of wide characters for which iswspace is true
and that is used to separate words within a line of text. The standard blank wide
<a name="7.29.2.1.4" href="#7.29.2.1.4"><h5>7.29.2.1.4 The iswcntrl function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswcntrl(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswcntrl function tests for any control wide character.
<a name="7.29.2.1.5" href="#7.29.2.1.5"><h5>7.29.2.1.5 The iswdigit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswdigit(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswdigit function tests for any wide character that corresponds to a decimal-digit
character (as defined in <a href="#5.2.1">5.2.1</a>).
<a name="7.29.2.1.6" href="#7.29.2.1.6"><h5>7.29.2.1.6 The iswgraph function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswgraph(wint_t wc);</pre>
-<!--page 465 indent 4-->
+<!--page 465 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswgraph function tests for any wide character for which iswprint is true and
iswspace is false.<sup><a href="#note342"><b>342)</b></a></sup>
<a name="7.29.2.1.7" href="#7.29.2.1.7"><h5>7.29.2.1.7 The iswlower function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswlower(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswlower function tests for any wide character that corresponds to a lowercase
letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
iswdigit, iswpunct, or iswspace is true.
<a name="7.29.2.1.8" href="#7.29.2.1.8"><h5>7.29.2.1.8 The iswprint function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswprint(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswprint function tests for any printing wide character.
<a name="7.29.2.1.9" href="#7.29.2.1.9"><h5>7.29.2.1.9 The iswpunct function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswpunct(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswpunct function tests for any printing wide character that is one of a locale-
specific set of punctuation wide characters for which neither iswspace nor iswalnum
is true.342)
<a name="7.29.2.1.10" href="#7.29.2.1.10"><h5>7.29.2.1.10 The iswspace function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswspace(wint_t wc);</pre>
-<!--page 466 indent 4-->
+<!--page 466 -->
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswspace function tests for any wide character that corresponds to a locale-specific
set of white-space wide characters for which none of iswalnum, iswgraph, or
iswpunct is true.
<a name="7.29.2.1.11" href="#7.29.2.1.11"><h5>7.29.2.1.11 The iswupper function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswupper(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswupper function tests for any wide character that corresponds to an uppercase
letter or is one of a locale-specific set of wide characters for which none of iswcntrl,
iswdigit, iswpunct, or iswspace is true.
<a name="7.29.2.1.12" href="#7.29.2.1.12"><h5>7.29.2.1.12 The iswxdigit function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswxdigit(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswxdigit function tests for any wide character that corresponds to a
hexadecimal-digit character (as defined in <a href="#6.4.4.1">6.4.4.1</a>).
<a name="7.29.2.2" href="#7.29.2.2"><h5>7.29.2.2 Extensible wide character classification functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions wctype and iswctype provide extensible wide character classification
as well as testing equivalent to that performed by the functions described in the previous
subclause (<a href="#7.29.2.1">7.29.2.1</a>).
<a name="7.29.2.2.1" href="#7.29.2.2.1"><h5>7.29.2.2.1 The iswctype function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
int iswctype(wint_t wc, wctype_t desc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The iswctype function determines whether the wide character wc has the property
described by desc. The current setting of the LC_CTYPE category shall be the same as
during the call to wctype that returned the value desc.
-<p><!--para 3-->
+<p><!--para 3 -->
Each of the following expressions has a truth-value equivalent to the call to the wide
character classification function (<a href="#7.29.2.1">7.29.2.1</a>) in the comment that follows the expression:
-<!--page 467 indent 4-->
+<!--page 467 -->
<pre>
iswctype(wc, wctype("alnum")) // iswalnum(wc)
iswctype(wc, wctype("alpha")) // iswalpha(wc)
iswctype(wc, wctype("upper")) // iswupper(wc)
iswctype(wc, wctype("xdigit")) // iswxdigit(wc)</pre>
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The iswctype function returns nonzero (true) if and only if the value of the wide
character wc has the property described by desc. If desc is zero, the iswctype
function returns zero (false).
<a name="7.29.2.2.2" href="#7.29.2.2.2"><h5>7.29.2.2.2 The wctype function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
wctype_t wctype(const char *property);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wctype function constructs a value with type wctype_t that describes a class of
wide characters identified by the string argument property.
-<p><!--para 3-->
+<p><!--para 3 -->
The strings listed in the description of the iswctype function shall be valid in all
locales as property arguments to the wctype function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If property identifies a valid class of wide characters according to the LC_CTYPE
category of the current locale, the wctype function returns a nonzero value that is valid
as the second argument to the iswctype function; otherwise, it returns zero.
-<!--page 468 indent 4-->
+<!--page 468 -->
<a name="7.29.3" href="#7.29.3"><h4>7.29.3 Wide character case mapping utilities</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.29"><wctype.h></a> declares several functions useful for mapping wide characters.
<a name="7.29.3.1" href="#7.29.3.1"><h5>7.29.3.1 Wide character case mapping functions</h5></a>
<a name="7.29.3.1.1" href="#7.29.3.1.1"><h5>7.29.3.1.1 The towlower function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
wint_t towlower(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The towlower function converts an uppercase letter to a corresponding lowercase letter.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a wide character for which iswupper is true and there are one or
more corresponding wide characters, as specified by the current locale, for which
iswlower is true, the towlower function returns one of the corresponding wide
<a name="7.29.3.1.2" href="#7.29.3.1.2"><h5>7.29.3.1.2 The towupper function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
wint_t towupper(wint_t wc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The towupper function converts a lowercase letter to a corresponding uppercase letter.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If the argument is a wide character for which iswlower is true and there are one or
more corresponding wide characters, as specified by the current locale, for which
iswupper is true, the towupper function returns one of the corresponding wide
returned unchanged.
<a name="7.29.3.2" href="#7.29.3.2"><h5>7.29.3.2 Extensible wide character case mapping functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions wctrans and towctrans provide extensible wide character mapping as
well as case mapping equivalent to that performed by the functions described in the
previous subclause (<a href="#7.29.3.1">7.29.3.1</a>).
-<!--page 469 indent 4-->
+<!--page 469 -->
<a name="7.29.3.2.1" href="#7.29.3.2.1"><h5>7.29.3.2.1 The towctrans function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
wint_t towctrans(wint_t wc, wctrans_t desc);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The towctrans function maps the wide character wc using the mapping described by
desc. The current setting of the LC_CTYPE category shall be the same as during the call
to wctrans that returned the value desc.
-<p><!--para 3-->
+<p><!--para 3 -->
Each of the following expressions behaves the same as the call to the wide character case
mapping function (<a href="#7.29.3.1">7.29.3.1</a>) in the comment that follows the expression:
<pre>
towctrans(wc, wctrans("tolower")) // towlower(wc)
towctrans(wc, wctrans("toupper")) // towupper(wc)</pre>
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The towctrans function returns the mapped value of wc using the mapping described
by desc. If desc is zero, the towctrans function returns the value of wc.
<a name="7.29.3.2.2" href="#7.29.3.2.2"><h5>7.29.3.2.2 The wctrans function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.29"><wctype.h></a>
wctrans_t wctrans(const char *property);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wctrans function constructs a value with type wctrans_t that describes a
mapping between wide characters identified by the string argument property.
-<p><!--para 3-->
+<p><!--para 3 -->
The strings listed in the description of the towctrans function shall be valid in all
locales as property arguments to the wctrans function.
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
If property identifies a valid mapping of wide characters according to the LC_CTYPE
category of the current locale, the wctrans function returns a nonzero value that is valid
as the second argument to the towctrans function; otherwise, it returns zero.
-<!--page 470 indent 4-->
+<!--page 470 -->
<a name="7.30" href="#7.30"><h3>7.30 Future library directions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following names are grouped under individual headers for convenience. All external
names described below are reserved no matter what headers are included by the program.
<a name="7.30.1" href="#7.30.1"><h4>7.30.1 Complex arithmetic <complex.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The function names
<pre>
cerf cexpm1 clog2
<a href="#7.3"><complex.h></a> header.
<a name="7.30.2" href="#7.30.2"><h4>7.30.2 Character handling <ctype.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with either is or to, and a lowercase letter may be added to
the declarations in the <a href="#7.4"><ctype.h></a> header.
<a name="7.30.3" href="#7.30.3"><h4>7.30.3 Errors <errno.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macros that begin with E and a digit or E and an uppercase letter may be added to the
declarations in the <a href="#7.5"><errno.h></a> header.
<a name="7.30.4" href="#7.30.4"><h4>7.30.4 Format conversion of integer types <inttypes.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macro names beginning with PRI or SCN followed by any lowercase letter or X may be
added to the macros defined in the <a href="#7.8"><inttypes.h></a> header.
<a name="7.30.5" href="#7.30.5"><h4>7.30.5 Localization <locale.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macros that begin with LC_ and an uppercase letter may be added to the definitions in
the <a href="#7.11"><locale.h></a> header.
<a name="7.30.6" href="#7.30.6"><h4>7.30.6 Signal handling <signal.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macros that begin with either SIG and an uppercase letter or SIG_ and an uppercase
letter may be added to the definitions in the <a href="#7.14"><signal.h></a> header.
<a name="7.30.7" href="#7.30.7"><h4>7.30.7 Boolean type and values <stdbool.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The ability to undefine and perhaps then redefine the macros bool, true, and false is
an obsolescent feature.
<a name="7.30.8" href="#7.30.8"><h4>7.30.8 Integer types <stdint.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Typedef names beginning with int or uint and ending with _t may be added to the
types defined in the <a href="#7.20"><stdint.h></a> header. Macro names beginning with INT or UINT
and ending with _MAX, _MIN, or _C may be added to the macros defined in the
<a href="#7.20"><stdint.h></a> header.
-<!--page 471 indent 4-->
+<!--page 471 -->
<a name="7.30.9" href="#7.30.9"><h4>7.30.9 Input/output <stdio.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Lowercase letters may be added to the conversion specifiers and length modifiers in
fprintf and fscanf. Other characters may be used in extensions.
-<p><!--para 2-->
+<p><!--para 2 -->
The use of ungetc on a binary stream where the file position indicator is zero prior to *
the call is an obsolescent feature.
<a name="7.30.10" href="#7.30.10"><h4>7.30.10 General utilities <stdlib.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with str and a lowercase letter may be added to the
declarations in the <a href="#7.22"><stdlib.h></a> header.
<a name="7.30.11" href="#7.30.11"><h4>7.30.11 String handling <string.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with str, mem, or wcs and a lowercase letter may be added
to the declarations in the <a href="#7.23"><string.h></a> header.
<a name="7.30.12" href="#7.30.12"><h4>7.30.12 Extended multibyte and wide character utilities <wchar.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with wcs and a lowercase letter may be added to the
declarations in the <a href="#7.28"><wchar.h></a> header.
-<p><!--para 2-->
+<p><!--para 2 -->
Lowercase letters may be added to the conversion specifiers and length modifiers in
fwprintf and fwscanf. Other characters may be used in extensions.
<a name="7.30.13" href="#7.30.13"><h4>7.30.13 Wide character classification and mapping utilities</h4></a>
<a href="#7.29"><wctype.h></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Function names that begin with is or to and a lowercase letter may be added to the
declarations in the <a href="#7.29"><wctype.h></a> header.
-<!--page 472 indent 4-->
+<!--page 472 -->
<a name="A" href="#A"><h2>Annex A</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Language syntax summary</pre>
string-literal
punctuator</pre>
(<a href="#6.4">6.4</a>) preprocessing-token:
-<!--page 473 indent 0-->
+<!--page 473 -->
<pre>
header-name
identifier
A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z</pre>
(<a href="#6.4.2.1">6.4.2.1</a>) digit: one of
-<!--page 474 indent 0-->
+<!--page 474 -->
<pre>
0 1 2 3 4 5 6 7 8 9</pre>
<pre>
1 2 3 4 5 6 7 8 9</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) octal-digit: one of
-<!--page 475 indent 0-->
+<!--page 475 -->
<pre>
0 1 2 3 4 5 6 7</pre>
(<a href="#6.4.4.1">6.4.4.1</a>) hexadecimal-digit: one of
e signopt digit-sequence
E signopt digit-sequence</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) sign: one of
-<!--page 476 indent 0-->
+<!--page 476 -->
<pre>
+ -</pre>
(<a href="#6.4.4.2">6.4.4.2</a>) digit-sequence:
the single-quote ', backslash \, or new-line character
escape-sequence</pre>
(<a href="#6.4.4.4">6.4.4.4</a>) escape-sequence:
-<!--page 477 indent 0-->
+<!--page 477 -->
<pre>
simple-escape-sequence
octal-escape-sequence
<a name="A.1.7" href="#A.1.7"><h4>A.1.7 Punctuators</h4></a>
(<a href="#6.4.6">6.4.6</a>) punctuator: one of
-<!--page 478 indent 0-->
+<!--page 478 -->
<pre>
[ ] ( ) { } . ->
++ -- & * + - ~ !
<a name="A.1.9" href="#A.1.9"><h4>A.1.9 Preprocessing numbers</h4></a>
(<a href="#6.4.8">6.4.8</a>) pp-number:
-<!--page 479 indent 0-->
+<!--page 479 -->
<pre>
digit
. digit
assignment-expression
argument-expression-list , assignment-expression</pre>
(<a href="#6.5.3">6.5.3</a>) unary-expression:
-<!--page 480 indent 0-->
+<!--page 480 -->
<pre>
postfix-expression
++ unary-expression
equality-expression
AND-expression & equality-expression</pre>
(<a href="#6.5.11">6.5.11</a>) exclusive-OR-expression:
-<!--page 481 indent 0-->
+<!--page 481 -->
<pre>
AND-expression
exclusive-OR-expression ^ AND-expression</pre>
function-specifier declaration-specifiersopt
alignment-specifier declaration-specifiersopt</pre>
(<a href="#6.7">6.7</a>) init-declarator-list:
-<!--page 482 indent 0-->
+<!--page 482 -->
<pre>
init-declarator
init-declarator-list , init-declarator</pre>
struct-declaration
struct-declaration-list struct-declaration</pre>
(<a href="#6.7.2.1">6.7.2.1</a>) struct-declaration:
-<!--page 483 indent 0-->
+<!--page 483 -->
<pre>
specifier-qualifier-list struct-declarator-listopt ;
static_assert-declaration</pre>
_Alignas ( type-name )
_Alignas ( constant-expression )</pre>
(<a href="#6.7.6">6.7.6</a>) declarator:
-<!--page 484 indent 0-->
+<!--page 484 -->
<pre>
pointeropt direct-declarator</pre>
(<a href="#6.7.6">6.7.6</a>) direct-declarator:
<pre>
specifier-qualifier-list abstract-declaratoropt</pre>
(<a href="#6.7.7">6.7.7</a>) abstract-declarator:
-<!--page 485 indent 0-->
+<!--page 485 -->
<pre>
pointer
pointeropt direct-abstract-declarator</pre>
[ constant-expression ]
. identifier</pre>
(<a href="#6.7.10">6.7.10</a>) static_assert-declaration:
-<!--page 486 indent 0-->
+<!--page 486 -->
<pre>
_Static_assert ( constant-expression , string-literal ) ;</pre>
for ( expressionopt ; expressionopt ; expressionopt ) statement
for ( declaration expressionopt ; expressionopt ) statement</pre>
(<a href="#6.8.6">6.8.6</a>) jump-statement:
-<!--page 487 indent 0-->
+<!--page 487 -->
<pre>
goto identifier ;
continue ;
elif-group
elif-groups elif-group</pre>
(<a href="#6.10">6.10</a>) elif-group:
-<!--page 488 indent 0-->
+<!--page 488 -->
<pre>
# elif constant-expression new-line groupopt</pre>
(<a href="#6.10">6.10</a>) else-group:
preprocessing-token
pp-tokens preprocessing-token</pre>
(<a href="#6.10">6.10</a>) new-line:
-<!--page 489 indent 0-->
+<!--page 489 -->
<pre>
the new-line character</pre>
void assert(scalar expression);</pre>
<a name="B.2" href="#B.2"><h3>B.2 Complex <complex.h></h3></a>
-<!--page 490 indent -1-->
-<!--page 491 indent 0-->
+<!--page 490 -->
+<!--page 491 -->
<pre>
__STDC_NO_COMPLEX__ imaginary
complex _Imaginary_I
errno_t</pre>
<a name="B.5" href="#B.5"><h3>B.5 Floating-point environment <fenv.h></h3></a>
-<!--page 492 indent 0-->
+<!--page 492 -->
<pre>
fenv_t FE_OVERFLOW FE_TOWARDZERO
fexcept_t FE_UNDERFLOW FE_UPWARD
FLT_DIG LDBL_MAX_10_EXP</pre>
<a name="B.7" href="#B.7"><h3>B.7 Format conversion of integer types <inttypes.h></h3></a>
-<!--page 493 indent 0-->
+<!--page 493 -->
<pre>
imaxdiv_t
PRIdN PRIdLEASTN PRIdFASTN PRIdMAX PRIdPTR
struct lconv *localeconv(void);</pre>
<a name="B.11" href="#B.11"><h3>B.11 Mathematics <math.h></h3></a>
-<!--page 494 indent -1-->
-<!--page 495 indent -1-->
-<!--page 496 indent -1-->
-<!--page 497 indent -1-->
-<!--page 498 indent 0-->
+<!--page 494 -->
+<!--page 495 -->
+<!--page 496 -->
+<!--page 497 -->
+<!--page 498 -->
<pre>
float_t FP_INFINITE FP_FAST_FMAL
double_t FP_NAN FP_ILOGB0
_Noreturn void longjmp(jmp_buf env, int val);</pre>
<a name="B.13" href="#B.13"><h3>B.13 Signal handling <signal.h></h3></a>
-<!--page 499 indent 0-->
+<!--page 499 -->
<pre>
sig_atomic_t SIG_IGN SIGILL SIGTERM
SIG_DFL SIGABRT SIGINT
void va_start(va_list ap, parmN);</pre>
<a name="B.16" href="#B.16"><h3>B.16 Atomics <stdatomic.h></h3></a>
-<!--page 500 indent -1-->
-<!--page 501 indent 0-->
+<!--page 500 -->
+<!--page 501 -->
<pre>
ATOMIC_CHAR_LOCK_FREE atomic_uint
ATOMIC_CHAR16_T_LOCK_FREE atomic_long
rsize_t</pre>
<a name="B.19" href="#B.19"><h3>B.19 Integer types <stdint.h></h3></a>
-<!--page 502 indent 0-->
+<!--page 502 -->
<pre>
intN_t INT_LEASTN_MIN PTRDIFF_MAX
uintN_t INT_LEASTN_MAX SIG_ATOMIC_MIN
RSIZE_MAX</pre>
<a name="B.20" href="#B.20"><h3>B.20 Input/output <stdio.h></h3></a>
-<!--page 503 indent -1-->
-<!--page 504 indent -1-->
-<!--page 505 indent 0-->
+<!--page 503 -->
+<!--page 504 -->
+<!--page 505 -->
<pre>
size_t _IOLBF FILENAME_MAX TMP_MAX
FILE _IONBF L_tmpnam stderr
char *gets_s(char *s, rsize_t n);</pre>
<a name="B.21" href="#B.21"><h3>B.21 General utilities <stdlib.h></h3></a>
-<!--page 506 indent -1-->
-<!--page 507 indent 0-->
+<!--page 506 -->
+<!--page 507 -->
<pre>
size_t ldiv_t EXIT_FAILURE MB_CUR_MAX
wchar_t lldiv_t EXIT_SUCCESS
const wchar_t * restrict src, rsize_t len);</pre>
<a name="B.22" href="#B.22"><h3>B.22 String handling <string.h></h3></a>
-<!--page 508 indent -1-->
-<!--page 509 indent 0-->
+<!--page 508 -->
+<!--page 509 -->
<pre>
size_t
NULL
pow fmin nearbyint creal</pre>
<a name="B.24" href="#B.24"><h3>B.24 Threads <threads.h></h3></a>
-<!--page 510 indent 0-->
+<!--page 510 -->
<pre>
ONCE_FLAG_INIT mtx_plain
TSS_DTOR_ITERATIONS mtx_recursive
int xtime_get(xtime *xt, int base);</pre>
<a name="B.25" href="#B.25"><h3>B.25 Date and time <time.h></h3></a>
-<!--page 511 indent 0-->
+<!--page 511 -->
<pre>
NULL size_t time_t
CLOCKS_PER_SEC clock_t struct tm
mbstate_t * restrict ps);</pre>
<a name="B.27" href="#B.27"><h3>B.27 Extended multibyte/wide character utilities <wchar.h></h3></a>
-<!--page 512 indent -1-->
-<!--page 513 indent -1-->
-<!--page 514 indent -1-->
-<!--page 515 indent -1-->
-<!--page 516 indent 0-->
+<!--page 512 -->
+<!--page 513 -->
+<!--page 514 -->
+<!--page 515 -->
+<!--page 516 -->
<pre>
wchar_t wint_t WCHAR_MAX
size_t struct tm WCHAR_MIN
mbstate_t * restrict ps);</pre>
<a name="B.28" href="#B.28"><h3>B.28 Wide character classification and mapping utilities <wctype.h></h3></a>
-<!--page 517 indent 4-->
+<!--page 517 -->
<pre>
wint_t wctrans_t wctype_t WEOF
int iswalnum(wint_t wc);
wctrans_t wctrans(const char *property);</pre>
<a name="C" href="#C"><h2>Annex C</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Sequence points</pre>
<li> Immediately before and immediately after each call to a comparison function, and
also between any call to a comparison function and any movement of the objects
passed as arguments to that call (<a href="#7.22.5">7.22.5</a>).
-<!--page 518 indent 4-->
+<!--page 518 -->
</ul>
<a name="D" href="#D"><h2>Annex D</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(normative)
Universal character names for identifiers</pre>
in identifiers.
<a name="D.1" href="#D.1"><h3>D.1 Ranges of characters allowed</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
00A8, 00AA, 00AD, 00AF, 00B2-00B5, 00B7-00BA, 00BC-00BE, 00C0-00D6,
00D8-00F6, 00F8-00FF
-<p><!--para 2-->
+<p><!--para 2 -->
0100-167F, 1681-180D, 180F-1FFF
-<p><!--para 3-->
+<p><!--para 3 -->
200B-200D, 202A-202E, 203F-2040, 2054, 2060-206F
-<p><!--para 4-->
+<p><!--para 4 -->
2070-218F, 2460-24FF, 2776-2793, 2C00-2DFF, 2E80-2FFF
-<p><!--para 5-->
+<p><!--para 5 -->
3004-3007, 3021-302F, 3031-303F
-<p><!--para 6-->
+<p><!--para 6 -->
3040-D7FF
-<p><!--para 7-->
+<p><!--para 7 -->
F900-FD3D, FD40-FDCF, FDF0-FE44, FE47-FFFD
-<p><!--para 8-->
+<p><!--para 8 -->
10000-1FFFD, 20000-2FFFD, 30000-3FFFD, 40000-4FFFD, 50000-5FFFD,
60000-6FFFD, 70000-7FFFD, 80000-8FFFD, 90000-9FFFD, A0000-AFFFD,
B0000-BFFFD, C0000-CFFFD, D0000-DFFFD, E0000-EFFFD
<a name="D.2" href="#D.2"><h3>D.2 Ranges of characters disallowed initially</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
0300-036F, 1DC0-1DFF, 20D0-20FF, FE20-FE2F
-<!--page 519 indent 4-->
+<!--page 519 -->
<a name="E" href="#E"><h2>Annex E</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Implementation limits</pre>
minimum magnitudes shown shall be replaced by implementation-defined magnitudes
with the same sign. The values shall all be constant expressions suitable for use in #if
preprocessing directives. The components are described further in <a href="#5.2.4.2.1">5.2.4.2.1</a>.
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
#define CHAR_BIT 8
#define CHAR_MAX UCHAR_MAX or SCHAR_MAX
FLT_ROUNDS, shall be constant expressions suitable for use in #if preprocessing
directives; all floating values shall be constant expressions. The components are
described further in <a href="#5.2.4.2.2">5.2.4.2.2</a>.
-<p><!--para 3-->
+<p><!--para 3 -->
The values given in the following list shall be replaced by implementation-defined
expressions:
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
#define FLT_EVAL_METHOD
#define FLT_ROUNDS</pre>
The values given in the following list shall be replaced by implementation-defined
constant expressions that are greater or equal in magnitude (absolute value) to those
shown, with the same sign:
-<!--page 520 indent 4-->
-<p><!--para 5-->
+<!--page 520 -->
+<p><!--para 5 -->
<pre>
#define DLB_DECIMAL_DIG 10
#define DBL_DIG 10
#define LDBL_MIN_EXP</pre>
The values given in the following list shall be replaced by implementation-defined
constant expressions with values that are greater than or equal to those shown:
-<p><!--para 6-->
+<p><!--para 6 -->
<pre>
#define DBL_MAX 1E+37
#define FLT_MAX 1E+37
#define LDBL_MAX 1E+37</pre>
The values given in the following list shall be replaced by implementation-defined
constant expressions with (positive) values that are less than or equal to those shown:
-<!--page 521 indent 4-->
+<!--page 521 -->
<pre>
#define DBL_EPSILON 1E-9
#define DBL_MIN 1E-37
IEC 60559 floating-point arithmetic</pre>
<a name="F.1" href="#F.1"><h3>F.1 Introduction</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This annex specifies C language support for the IEC 60559 floating-point standard. The
IEC 60559 floating-point standard is specifically Binary floating-point arithmetic for
microprocessor systems, second edition (IEC 60559:1989), previously designated
</small>
<a name="F.2" href="#F.2"><h3>F.2 Types</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The C floating types match the IEC 60559 formats as follows:
<ul>
<li> The float type matches the IEC 60559 single format.
-<!--page 522 indent 4-->
+<!--page 522 -->
Recommended practice
-<p><!--para 2-->
+<p><!--para 2 -->
The long double type should match an IEC 60559 extended format.
<h6>footnotes</h6>
</small>
<a name="F.2.1" href="#F.2.1"><h4>F.2.1 Infinities, signed zeros, and NaNs</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This specification does not define the behavior of signaling NaNs.<sup><a href="#note346"><b>346)</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.
</small>
<a name="F.3" href="#F.3"><h3>F.3 Operators and functions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
C operators and functions provide IEC 60559 required and recommended facilities as
listed below.
<ul>
strtold, fprintf, fscanf, and related library functions in <a href="#7.22"><stdlib.h></a>,
-<!--page 523 indent 0-->
+<!--page 523 -->
<a href="#7.21"><stdio.h></a>, and <a href="#7.28"><wchar.h></a> provide IEC 60559 binary-decimal conversions. The
strtold function in <a href="#7.22"><stdlib.h></a> provides the conv function recommended in the
Appendix to ANSI/IEEE 854.
Appendix to IEC 60559, but following the newer specifications in ANSI/IEEE 854.
<li> The nextafter and nexttoward functions in <a href="#7.12"><math.h></a> provide the nextafter
function recommended in the Appendix to IEC 60559 (but with a minor change to
-<!--page 524 indent 4-->
+<!--page 524 -->
better handle signed zeros).
<li> The isfinite macro in <a href="#7.12"><math.h></a> provides the finite function recommended in
the Appendix to IEC 60559.
</ul>
<a name="F.4" href="#F.4"><h3>F.4 Floating to integer conversion</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
If the integer type is _Bool, <a href="#6.3.1.2">6.3.1.2</a> applies and no floating-point exceptions are raised
(even for NaN). Otherwise, if the floating value is infinite or NaN or if the integral part
of the floating value exceeds the range of the integer type, then the ''invalid'' floating-
</small>
<a name="F.5" href="#F.5"><h3>F.5 Binary-decimal conversion</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Conversion from the widest supported IEC 60559 format to decimal with
DECIMAL_DIG digits and back is the identity function.<sup><a href="#note348"><b>348)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 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
-<!--page 525 indent 4-->
-<p><!--para 3-->
+<!--page 525 -->
+<p><!--para 3 -->
Functions such as strtod that convert character sequences to floating types honor the
rounding direction. Hence, if the rounding direction might be upward or downward, the
implementation cannot convert a minus-signed sequence by negating the converted
</small>
<a name="F.7" href="#F.7"><h3>F.7 Contracted expressions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A contracted expression is correctly rounded (once) and treats infinities, NaNs, signed
zeros, subnormals, and the rounding directions in a manner consistent with the basic
arithmetic operations covered by IEC 60559.
Recommended practice
-<p><!--para 2-->
+<p><!--para 2 -->
A contracted expression should raise floating-point exceptions in a manner generally
consistent with the basic arithmetic operations. *
<a name="F.8" href="#F.8"><h3>F.8 Floating-point environment</h3></a>
-<p><!--para 1-->
+<p><!--para 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
</small>
<a name="F.8.1" href="#F.8.1"><h4>F.8.1 Environment management</h4></a>
-<p><!--para 1-->
+<p><!--para 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
-<!--page 526 indent 4-->
+<!--page 526 -->
<h6>footnotes</h6>
<p><small><a name="note351" href="#note351">351)</a> If the state for the FENV_ACCESS pragma is ''off'', the implementation is free to assume the floating-
</small>
<a name="F.8.2" href="#F.8.2"><h4>F.8.2 Translation</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
During translation the IEC 60559 default modes are in effect:
<ul>
<li> The rounding direction mode is rounding to nearest.
<li> Trapping or stopping (if supported) is disabled on all floating-point exceptions.
</ul>
Recommended practice
-<p><!--para 2-->
+<p><!--para 2 -->
The implementation should produce a diagnostic message for each translation-time
floating-point exception, other than ''inexact'';<sup><a href="#note352"><b>352)</b></a></sup> the implementation should then
proceed with the translation of the program.
</small>
<a name="F.8.3" href="#F.8.3"><h4>F.8.3 Execution</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
At program startup the floating-point environment is initialized as prescribed by
IEC 60559:
<ul>
</ul>
<a name="F.8.4" href="#F.8.4"><h4>F.8.4 Constant expressions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An arithmetic constant expression of floating type, other than one in an initializer for an
object that has static or thread 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'').<sup><a href="#note353"><b>353)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE
-<!--page 527 indent 4-->
-<p><!--para 3-->
+<!--page 527 -->
+<p><!--para 3 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS ON
</small>
<a name="F.8.5" href="#F.8.5"><h4>F.8.5 Initialization</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
All computation for automatic initialization is done (as if) at execution time; thus, it is
affected by any operative modes and raises floating-point exceptions as required by
IEC 60559 (provided the state for the FENV_ACCESS pragma is ''on''). All computation
for initialization of objects that have static or thread storage duration is done (as if) at
translation time.
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
#include <a href="#7.6"><fenv.h></a>
#pragma STDC FENV_ACCESS ON
-<!--page 528 indent 4-->
+<!--page 528 -->
their internal representations occur at translation time in all cases.
</small>
<a name="F.8.6" href="#F.8.6"><h4>F.8.6 Changing the environment</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Operations defined in <a href="#6.5">6.5</a> and functions and macros defined for the standard libraries
change floating-point status flags and control modes just as indicated by their
specifications (including conformance to IEC 60559). They do not change flags or modes
(so as to be detectable by the user) in any other cases.
-<p><!--para 2-->
+<p><!--para 2 -->
If the argument to the feraiseexcept function in <a href="#7.6"><fenv.h></a> represents IEC 60559
valid coincident floating-point exceptions for atomic operations (namely ''overflow'' and
''inexact'', or ''underflow'' and ''inexact''), then ''overflow'' or ''underflow'' is raised
before ''inexact''.
<a name="F.9" href="#F.9"><h3>F.9 Optimization</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This section identifies code transformations that might subvert IEC 60559-specified
behavior, and others that do not.
<a name="F.9.1" href="#F.9.1"><h4>F.9.1 Global transformations</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Floating-point arithmetic operations and external function calls may entail side effects
which optimization shall honor, at least where the state of the FENV_ACCESS pragma is
''on''. The flags and modes in the floating-point environment may be regarded as global
variables; floating-point operations (+, *, etc.) implicitly read the modes and write the
flags.
-<p><!--para 2-->
+<p><!--para 2 -->
Concern about side effects may inhibit code motion and removal of seemingly useless
code. For example, in
<pre>
body might not execute (maybe 0 >= n), x + 1 cannot be moved out of the loop. (Of
course these optimizations are valid if the implementation can rule out the nettlesome
cases.)
-<p><!--para 3-->
+<p><!--para 3 -->
This specification does not require support for trap handlers that maintain information
about the order or count of floating-point exceptions. Therefore, between function calls,
floating-point exceptions need not be precise: the actual order and number of occurrences
of floating-point exceptions (> 1) may vary from what the source code expresses. Thus,
-<!--page 529 indent 4-->
+<!--page 529 -->
the preceding loop could be treated as
<pre>
if (0 < n) x + 1;</pre>
<a name="F.9.2" href="#F.9.2"><h4>F.9.2 Expression transformations</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
x/2 <-> x x 0.5 Although similar transformations involving inexact constants
<pre>
generally do not yield numerically equivalent expressions, if the
-(+0) yields -0, but 0 - (+0) yields +0 (unless rounding is
downward).</pre>
-<!--page 530 indent 4-->
+<!--page 530 -->
<h6>footnotes</h6>
<p><small><a name="note355" href="#note355">355)</a> Strict support for signaling NaNs -- not required by this specification -- would invalidate these and
</small>
<a name="F.9.3" href="#F.9.3"><h4>F.9.3 Relational operators</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
x != x -> false The expression x != x is true if x is a NaN.
x = x -> true The expression x = x is false if x is a NaN.
x < y -> isless(x,y) (and similarly for <=, >, >=) Though numerically equal, these
is ''off''.</pre>
The sense of relational operators shall be maintained. This includes handling unordered
cases as expressed by the source code.
-<p><!--para 2-->
+<p><!--para 2 -->
EXAMPLE
<pre>
// calls g and raises ''invalid'' if a and b are unordered
else
g();</pre>
but is equivalent to
-<!--page 531 indent 4-->
+<!--page 531 -->
<pre>
if (!(a < b))
g();
<a name="F.9.4" href="#F.9.4"><h4>F.9.4 Constant arithmetic</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The implementation shall honor floating-point exceptions raised by execution-time
constant arithmetic wherever the state of the FENV_ACCESS pragma is ''on''. (See <a href="#F.8.4">F.8.4</a>
and <a href="#F.8.5">F.8.5</a>.) An operation on constants that raises no floating-point exception can be
</small>
<a name="F.10" href="#F.10"><h3>F.10 Mathematics <math.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This subclause contains specifications of <a href="#7.12"><math.h></a> facilities that are particularly suited
for IEC 60559 implementations.
-<p><!--para 2-->
+<p><!--para 2 -->
The Standard C macro HUGE_VAL and its float and long double analogs,
HUGE_VALF and HUGE_VALL, expand to expressions whose values are positive
infinities.
-<p><!--para 3-->
+<p><!--para 3 -->
Special cases for functions in <a href="#7.12"><math.h></a> are covered directly or indirectly by
IEC 60559. The functions that IEC 60559 specifies directly are identified in <a href="#F.3">F.3</a>. The
other functions in <a href="#7.12"><math.h></a> treat infinities, NaNs, signed zeros, subnormals, and
(provided the state of the FENV_ACCESS pragma is ''on'') the floating-point status flags
in a manner consistent with the basic arithmetic operations covered by IEC 60559.
-<p><!--para 4-->
+<p><!--para 4 -->
The expression math_errhandling & MATH_ERREXCEPT shall evaluate to a
nonzero value.
-<p><!--para 5-->
+<p><!--para 5 -->
The ''invalid'' and ''divide-by-zero'' floating-point exceptions are raised as specified in
subsequent subclauses of this annex.
-<p><!--para 6-->
+<p><!--para 6 -->
The ''overflow'' floating-point exception is raised whenever an infinity -- or, because of
rounding direction, a maximal-magnitude finite number -- is returned in lieu of a value
whose magnitude is too large.
-<p><!--para 7-->
+<p><!--para 7 -->
The ''underflow'' floating-point exception is raised whenever a result is tiny (essentially
subnormal or zero) and suffers loss of accuracy.<sup><a href="#note358"><b>358)</b></a></sup>
-<!--page 532 indent 5-->
-<p><!--para 8-->
+<!--page 532 -->
+<p><!--para 8 -->
Whether or when library functions raise the ''inexact'' floating-point exception is
unspecified, unless explicitly specified otherwise.
-<p><!--para 9-->
+<p><!--para 9 -->
Whether or when library functions raise an undeserved ''underflow'' floating-point
exception is unspecified.<sup><a href="#note359"><b>359)</b></a></sup> Otherwise, as implied by <a href="#F.8.6">F.8.6</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.
-<p><!--para 10-->
+<p><!--para 10 -->
Whether the functions honor the rounding direction mode is implementation-defined,
unless explicitly specified otherwise.
-<p><!--para 11-->
+<p><!--para 11 -->
Functions with a NaN argument return a NaN result and raise no floating-point exception,
except where stated otherwise.
-<p><!--para 12-->
+<p><!--para 12 -->
The specifications in the following subclauses append to the definitions in <a href="#7.12"><math.h></a>.
For families of functions, the specifications apply to all of the functions even though only
the principal function is shown. Unless otherwise specified, where the symbol ''(+-)''
occurs in both an argument and the result, the result has the same sign as the argument.
Recommended practice
-<p><!--para 13-->
+<p><!--para 13 -->
If a function with one or more NaN arguments returns a NaN result, the result should be
the same as one of the NaN arguments (after possible type conversion), except perhaps
for the sign.
<a name="F.10.1" href="#F.10.1"><h4>F.10.1 Trigonometric functions</h4></a>
<a name="F.10.1.1" href="#F.10.1.1"><h5>F.10.1.1 The acos functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> acos(1) returns +0.
<li> acos(x) returns a NaN and raises the ''invalid'' floating-point exception for
</ul>
<a name="F.10.1.2" href="#F.10.1.2"><h5>F.10.1.2 The asin functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> asin((+-)0) returns (+-)0.
<li> asin(x) returns a NaN and raises the ''invalid'' floating-point exception for
-<!--page 533 indent 4-->
+<!--page 533 -->
</ul>
<a name="F.10.1.3" href="#F.10.1.3"><h5>F.10.1.3 The atan functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> atan((+-)0) returns (+-)0.
<li> atan((+-)(inf)) returns (+-)pi /2.
</ul>
<a name="F.10.1.4" href="#F.10.1.4"><h5>F.10.1.4 The atan2 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> atan2((+-)0, -0) returns (+-)pi .<sup><a href="#note360"><b>360)</b></a></sup>
<li> atan2((+-)0, +0) returns (+-)0.
</small>
<a name="F.10.1.5" href="#F.10.1.5"><h5>F.10.1.5 The cos functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cos((+-)0) returns 1.
<li> cos((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
</ul>
<a name="F.10.1.6" href="#F.10.1.6"><h5>F.10.1.6 The sin functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> sin((+-)0) returns (+-)0.
<li> sin((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
</ul>
<a name="F.10.1.7" href="#F.10.1.7"><h5>F.10.1.7 The tan functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> tan((+-)0) returns (+-)0.
<li> tan((+-)(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
-<!--page 534 indent 4-->
+<!--page 534 -->
</ul>
<a name="F.10.2" href="#F.10.2"><h4>F.10.2 Hyperbolic functions</h4></a>
<a name="F.10.2.1" href="#F.10.2.1"><h5>F.10.2.1 The acosh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> acosh(1) returns +0.
<li> acosh(x) returns a NaN and raises the ''invalid'' floating-point exception for x < 1.
</ul>
<a name="F.10.2.2" href="#F.10.2.2"><h5>F.10.2.2 The asinh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> asinh((+-)0) returns (+-)0.
<li> asinh((+-)(inf)) returns (+-)(inf).
</ul>
<a name="F.10.2.3" href="#F.10.2.3"><h5>F.10.2.3 The atanh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> atanh((+-)0) returns (+-)0.
<li> atanh((+-)1) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception.
</ul>
<a name="F.10.2.4" href="#F.10.2.4"><h5>F.10.2.4 The cosh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cosh((+-)0) returns 1.
<li> cosh((+-)(inf)) returns +(inf).
</ul>
<a name="F.10.2.5" href="#F.10.2.5"><h5>F.10.2.5 The sinh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> sinh((+-)0) returns (+-)0.
<li> sinh((+-)(inf)) returns (+-)(inf).
</ul>
<a name="F.10.2.6" href="#F.10.2.6"><h5>F.10.2.6 The tanh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> tanh((+-)0) returns (+-)0.
<li> tanh((+-)(inf)) returns (+-)1.
<a name="F.10.3" href="#F.10.3"><h4>F.10.3 Exponential and logarithmic functions</h4></a>
<a name="F.10.3.1" href="#F.10.3.1"><h5>F.10.3.1 The exp functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> exp((+-)0) returns 1.
<li> exp(-(inf)) returns +0.
<li> exp(+(inf)) returns +(inf).
-<!--page 535 indent 4-->
+<!--page 535 -->
</ul>
<a name="F.10.3.2" href="#F.10.3.2"><h5>F.10.3.2 The exp2 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> exp2((+-)0) returns 1.
<li> exp2(-(inf)) returns +0.
</ul>
<a name="F.10.3.3" href="#F.10.3.3"><h5>F.10.3.3 The expm1 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> expm1((+-)0) returns (+-)0.
<li> expm1(-(inf)) returns -1.
</ul>
<a name="F.10.3.4" href="#F.10.3.4"><h5>F.10.3.4 The frexp functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> frexp((+-)0, exp) returns (+-)0, and stores 0 in the object pointed to by exp.
<li> frexp((+-)(inf), exp) returns (+-)(inf), and stores an unspecified value in the object
<li> frexp(NaN, exp) stores an unspecified value in the object pointed to by exp
(and returns a NaN).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
frexp raises no floating-point exceptions.
-<p><!--para 3-->
+<p><!--para 3 -->
When the radix of the argument is a power of 2, the returned value is exact and is
independent of the current rounding direction mode.
-<p><!--para 4-->
+<p><!--para 4 -->
On a binary system, the body of the frexp function might be
<pre>
{
}</pre>
<a name="F.10.3.5" href="#F.10.3.5"><h5>F.10.3.5 The ilogb functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When the correct result is representable in the range of the return type, the returned value
is exact and is independent of the current rounding direction mode.
-<p><!--para 2-->
+<p><!--para 2 -->
If the correct result is outside the range of the return type, the numeric result is
unspecified and the ''invalid'' floating-point exception is raised.
-<!--page 536 indent 4-->
+<!--page 536 -->
<a name="F.10.3.6" href="#F.10.3.6"><h5>F.10.3.6 The ldexp functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
On a binary system, ldexp(x, exp) is equivalent to scalbn(x, exp).
<a name="F.10.3.7" href="#F.10.3.7"><h5>F.10.3.7 The log functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> log((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> log(1) returns +0.
</ul>
<a name="F.10.3.8" href="#F.10.3.8"><h5>F.10.3.8 The log10 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> log10((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> log10(1) returns +0.
</ul>
<a name="F.10.3.9" href="#F.10.3.9"><h5>F.10.3.9 The log1p functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> log1p((+-)0) returns (+-)0.
<li> log1p(-1) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
</ul>
<a name="F.10.3.10" href="#F.10.3.10"><h5>F.10.3.10 The log2 functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> log2((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> log2(1) returns +0.
</ul>
<a name="F.10.3.11" href="#F.10.3.11"><h5>F.10.3.11 The logb functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> logb((+-)0) returns -(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> logb((+-)(inf)) returns +(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is exact and is independent of the current rounding direction mode.
-<!--page 537 indent 4-->
+<!--page 537 -->
<a name="F.10.3.12" href="#F.10.3.12"><h5>F.10.3.12 The modf functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> modf((+-)x, iptr) returns a result with the same sign as x.
<li> modf((+-)(inf), iptr) returns (+-)0 and stores (+-)(inf) in the object pointed to by iptr.
<li> modf(NaN, iptr) stores a NaN in the object pointed to by iptr (and returns a
NaN).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The returned values are exact and are independent of the current rounding direction
mode.
-<p><!--para 3-->
+<p><!--para 3 -->
modf behaves as though implemented by
<pre>
#include <a href="#7.12"><math.h></a>
}</pre>
<a name="F.10.3.13" href="#F.10.3.13"><h5>F.10.3.13 The scalbn and scalbln functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> scalbn((+-)0, n) returns (+-)0.
<li> scalbn(x, 0) returns x.
<li> scalbn((+-)(inf), n) returns (+-)(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
If the calculation does not overflow or underflow, the returned value is exact and
independent of the current rounding direction mode.
-<!--page 538 indent 4-->
+<!--page 538 -->
<a name="F.10.4" href="#F.10.4"><h4>F.10.4 Power and absolute value functions</h4></a>
<a name="F.10.4.1" href="#F.10.4.1"><h5>F.10.4.1 The cbrt functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cbrt((+-)0) returns (+-)0.
<li> cbrt((+-)(inf)) returns (+-)(inf).
</ul>
<a name="F.10.4.2" href="#F.10.4.2"><h5>F.10.4.2 The fabs functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> fabs((+-)0) returns +0.
<li> fabs((+-)(inf)) returns +(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is exact and is independent of the current rounding direction mode.
<a name="F.10.4.3" href="#F.10.4.3"><h5>F.10.4.3 The hypot functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> hypot(x, y), hypot(y, x), and hypot(x, -y) are equivalent.
<li> hypot(x, (+-)0) is equivalent to fabs(x).
</ul>
<a name="F.10.4.4" href="#F.10.4.4"><h5>F.10.4.4 The pow functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> pow((+-)0, y) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception
for y an odd integer < 0.
<li> pow(x, -(inf)) returns +0 for | x | > 1.
<li> pow(x, +(inf)) returns +0 for | x | < 1.
<li> pow(x, +(inf)) returns +(inf) for | x | > 1.
-<!--page 539 indent 4-->
+<!--page 539 -->
<li> pow(-(inf), y) returns -0 for y an odd integer < 0.
<li> pow(-(inf), y) returns +0 for y < 0 and not an odd integer.
<li> pow(-(inf), y) returns -(inf) for y an odd integer > 0.
</ul>
<a name="F.10.4.5" href="#F.10.4.5"><h5>F.10.4.5 The sqrt functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
sqrt is fully specified as a basic arithmetic operation in IEC 60559. The returned value
is dependent on the current rounding direction mode.
<a name="F.10.5" href="#F.10.5"><h4>F.10.5 Error and gamma functions</h4></a>
<a name="F.10.5.1" href="#F.10.5.1"><h5>F.10.5.1 The erf functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> erf((+-)0) returns (+-)0.
<li> erf((+-)(inf)) returns (+-)1.
</ul>
<a name="F.10.5.2" href="#F.10.5.2"><h5>F.10.5.2 The erfc functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> erfc(-(inf)) returns 2.
<li> erfc(+(inf)) returns +0.
</ul>
<a name="F.10.5.3" href="#F.10.5.3"><h5>F.10.5.3 The lgamma functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> lgamma(1) returns +0.
<li> lgamma(2) returns +0.
</ul>
<a name="F.10.5.4" href="#F.10.5.4"><h5>F.10.5.4 The tgamma functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> tgamma((+-)0) returns (+-)(inf) and raises the ''divide-by-zero'' floating-point exception.
<li> tgamma(x) returns a NaN and raises the ''invalid'' floating-point exception for x a
negative integer.
<li> tgamma(-(inf)) returns a NaN and raises the ''invalid'' floating-point exception.
<li> tgamma(+(inf)) returns +(inf).
-<!--page 540 indent 4-->
+<!--page 540 -->
</ul>
<a name="F.10.6" href="#F.10.6"><h4>F.10.6 Nearest integer functions</h4></a>
<a name="F.10.6.1" href="#F.10.6.1"><h5>F.10.6.1 The ceil functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> ceil((+-)0) returns (+-)0.
<li> ceil((+-)(inf)) returns (+-)(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is independent of the current rounding direction mode.
-<p><!--para 3-->
+<p><!--para 3 -->
The double version of ceil behaves as though implemented by
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.6"><fenv.h></a>
exception for finite non-integer arguments, as this implementation does.
<a name="F.10.6.2" href="#F.10.6.2"><h5>F.10.6.2 The floor functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> floor((+-)0) returns (+-)0.
<li> floor((+-)(inf)) returns (+-)(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value and is independent of the current rounding direction mode.
-<p><!--para 3-->
+<p><!--para 3 -->
See the sample implementation for ceil in <a href="#F.10.6.1">F.10.6.1</a>. The floor functions may, but are
not required to, raise the ''inexact'' floating-point exception for finite non-integer
arguments, as that implementation does.
<a name="F.10.6.3" href="#F.10.6.3"><h5>F.10.6.3 The nearbyint functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The nearbyint functions use IEC 60559 rounding according to the current rounding
direction. They do not raise the ''inexact'' floating-point exception if the result differs in
value from the argument.
<ul>
<li> nearbyint((+-)0) returns (+-)0 (for all rounding directions).
<li> nearbyint((+-)(inf)) returns (+-)(inf) (for all rounding directions).
-<!--page 541 indent 4-->
+<!--page 541 -->
</ul>
<a name="F.10.6.4" href="#F.10.6.4"><h5>F.10.6.4 The rint functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The rint functions differ from the nearbyint functions only in that they do raise the
''inexact'' floating-point exception if the result differs in value from the argument.
<a name="F.10.6.5" href="#F.10.6.5"><h5>F.10.6.5 The lrint and llrint functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The lrint and llrint functions provide floating-to-integer conversion as prescribed
by IEC 60559. They round according to the current rounding direction. If the rounded
value is outside the range of the return type, the numeric result is unspecified and the
exception.
<a name="F.10.6.6" href="#F.10.6.6"><h5>F.10.6.6 The round functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> round((+-)0) returns (+-)0.
<li> round((+-)(inf)) returns (+-)(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is independent of the current rounding direction mode.
-<p><!--para 3-->
+<p><!--para 3 -->
The double version of round behaves as though implemented by
<pre>
#include <a href="#7.12"><math.h></a>
}</pre>
The round functions may, but are not required to, raise the ''inexact'' floating-point
exception for finite non-integer numeric arguments, as this implementation does.
-<!--page 542 indent 4-->
+<!--page 542 -->
<a name="F.10.6.7" href="#F.10.6.7"><h5>F.10.6.7 The lround and llround functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The lround and llround functions differ from the lrint and llrint functions
with the default rounding direction just in that the lround and llround functions
round halfway cases away from zero and need not raise the ''inexact'' floating-point
exception for non-integer arguments that round to within the range of the return type.
<a name="F.10.6.8" href="#F.10.6.8"><h5>F.10.6.8 The trunc functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The trunc functions use IEC 60559 rounding toward zero (regardless of the current
rounding direction). The returned value is exact.
<ul>
<li> trunc((+-)0) returns (+-)0.
<li> trunc((+-)(inf)) returns (+-)(inf).
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is independent of the current rounding direction mode. The trunc
functions may, but are not required to, raise the ''inexact'' floating-point exception for
finite non-integer arguments.
<a name="F.10.7" href="#F.10.7"><h4>F.10.7 Remainder functions</h4></a>
<a name="F.10.7.1" href="#F.10.7.1"><h5>F.10.7.1 The fmod functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> fmod((+-)0, y) returns (+-)0 for y not zero.
<li> fmod(x, y) returns a NaN and raises the ''invalid'' floating-point exception for x
infinite or y zero (and neither is a NaN).
<li> fmod(x, (+-)(inf)) returns x for x not infinite.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
When subnormal results are supported, the returned value is exact and is independent of
the current rounding direction mode.
-<p><!--para 3-->
+<p><!--para 3 -->
The double version of fmod behaves as though implemented by
-<!--page 543 indent 4-->
+<!--page 543 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.6"><fenv.h></a>
}</pre>
<a name="F.10.7.2" href="#F.10.7.2"><h5>F.10.7.2 The remainder functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The remainder functions are fully specified as a basic arithmetic operation in
IEC 60559.
-<p><!--para 2-->
+<p><!--para 2 -->
When subnormal results are supported, the returned value is exact and is independent of
the current rounding direction mode.
<a name="F.10.7.3" href="#F.10.7.3"><h5>F.10.7.3 The remquo functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The remquo functions follow the specifications for the remainder functions. They
have no further specifications special to IEC 60559 implementations.
-<p><!--para 2-->
+<p><!--para 2 -->
When subnormal results are supported, the returned value is exact and is independent of
the current rounding direction mode.
<a name="F.10.8" href="#F.10.8"><h4>F.10.8 Manipulation functions</h4></a>
<a name="F.10.8.1" href="#F.10.8.1"><h5>F.10.8.1 The copysign functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
copysign is specified in the Appendix to IEC 60559.
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is exact and is independent of the current rounding direction mode.
<a name="F.10.8.2" href="#F.10.8.2"><h5>F.10.8.2 The nan functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
All IEC 60559 implementations support quiet NaNs, in all floating formats.
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is exact and is independent of the current rounding direction mode.
<a name="F.10.8.3" href="#F.10.8.3"><h5>F.10.8.3 The nextafter functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> nextafter(x, y) raises the ''overflow'' and ''inexact'' floating-point exceptions
for x finite and the function value infinite.
<li> nextafter(x, y) raises the ''underflow'' and ''inexact'' floating-point
exceptions for the function value subnormal or zero and x != y.
</ul>
-<p><!--para 2-->
+<p><!--para 2 -->
Even though underflow or overflow can occur, the returned value is independent of the
current rounding direction mode.
<a name="F.10.8.4" href="#F.10.8.4"><h5>F.10.8.4 The nexttoward functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
No additional requirements beyond those on nextafter.
-<p><!--para 2-->
+<p><!--para 2 -->
Even though underflow or overflow can occur, the returned value is independent of the
current rounding direction mode.
-<!--page 544 indent 4-->
+<!--page 544 -->
<a name="F.10.9" href="#F.10.9"><h4>F.10.9 Maximum, minimum, and positive difference functions</h4></a>
<a name="F.10.9.1" href="#F.10.9.1"><h5>F.10.9.1 The fdim functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
No additional requirements.
<a name="F.10.9.2" href="#F.10.9.2"><h5>F.10.9.2 The fmax functions</h5></a>
-<p><!--para 1-->
+<p><!--para 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).
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is exact and is independent of the current rounding direction mode.
-<p><!--para 3-->
+<p><!--para 3 -->
The body of the fmax function might be<sup><a href="#note361"><b>361)</b></a></sup>
<pre>
{ return (isgreaterequal(x, y) ||
</small>
<a name="F.10.9.3" href="#F.10.9.3"><h5>F.10.9.3 The fmin functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The fmin functions are analogous to the fmax functions (see <a href="#F.10.9.2">F.10.9.2</a>).
-<p><!--para 2-->
+<p><!--para 2 -->
The returned value is exact and is independent of the current rounding direction mode.
<a name="F.10.10" href="#F.10.10"><h4>F.10.10 Floating multiply-add</h4></a>
<a name="F.10.10.1" href="#F.10.10.1"><h5>F.10.10.1 The fma functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> fma(x, y, z) computes xy + z, correctly rounded once.
<li> fma(x, y, z) returns a NaN and optionally raises the ''invalid'' floating-point
-<!--page 545 indent 4-->
+<!--page 545 -->
</ul>
<a name="F.10.11" href="#F.10.11"><h4>F.10.11 Comparison macros</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Relational operators and their corresponding comparison macros (<a href="#7.12.14">7.12.14</a>) produce
equivalent result values, even if argument values are represented in wider formats. Thus,
comparison macro arguments represented in formats wider than their semantic types are
of relational operators to their semantic types. The standard wide evaluation methods
characterized by FLT_EVAL_METHOD equal to 1 or 2 (<a href="#5.2.4.2.2">5.2.4.2.2</a>), do not convert
operands of relational operators to their semantic types.
-<!--page 546 indent 4-->
+<!--page 546 -->
<a name="G" href="#G"><h2>Annex G</h2></a>
<pre>
IEC 60559-compatible complex arithmetic</pre>
<a name="G.1" href="#G.1"><h3>G.1 Introduction</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This annex supplements <a href="#F">annex F</a> to specify complex arithmetic for compatibility with
IEC 60559 real floating-point arithmetic. An implementation that defines *
__STDC_IEC_559_COMPLEX__ shall conform to the specifications in this annex.<sup><a href="#note362"><b>362)</b></a></sup>
</small>
<a name="G.2" href="#G.2"><h3>G.2 Types</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
There is a new keyword _Imaginary, which is used to specify imaginary types. It is
used as a type specifier within declaration specifiers in the same way as _Complex is
(thus, _Imaginary float is a valid type name).
-<p><!--para 2-->
+<p><!--para 2 -->
There are three imaginary types, designated as float _Imaginary, double
_Imaginary, and long double _Imaginary. The imaginary types (along with
the real floating and complex types) are floating types.
-<p><!--para 3-->
+<p><!--para 3 -->
For imaginary types, the corresponding real type is given by deleting the keyword
_Imaginary from the type name.
-<p><!--para 4-->
+<p><!--para 4 -->
Each imaginary type has the same representation and alignment requirements as the
corresponding real type. The value of an object of imaginary type is the value of the real
representation times the imaginary unit.
-<p><!--para 5-->
+<p><!--para 5 -->
The imaginary type domain comprises the imaginary types.
<a name="G.3" href="#G.3"><h3>G.3 Conventions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A complex or imaginary value with at least one infinite part is regarded as an infinity
(even if its other part is a NaN). A complex or imaginary value is a finite number if each
of its parts is a finite number (neither infinite nor NaN). A complex or imaginary value is
-<!--page 547 indent 4-->
+<!--page 547 -->
<a name="G.4" href="#G.4"><h3>G.4 Conversions</h3></a>
<a name="G.4.1" href="#G.4.1"><h4>G.4.1 Imaginary types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Conversions among imaginary types follow rules analogous to those for real floating
types.
<a name="G.4.2" href="#G.4.2"><h4>G.4.2 Real and imaginary</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value of imaginary type is converted to a real type other than _Bool,<sup><a href="#note363"><b>363)</b></a></sup> the
result is a positive zero.
-<p><!--para 2-->
+<p><!--para 2 -->
When a value of real type is converted to an imaginary type, the result is a positive
imaginary zero.
</small>
<a name="G.4.3" href="#G.4.3"><h4>G.4.3 Imaginary and complex</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
When a value of imaginary type is converted to a complex type, the real part of the
complex result value is a positive zero and the imaginary part of the complex result value
is determined by the conversion rules for the corresponding real types.
-<p><!--para 2-->
+<p><!--para 2 -->
When a value of complex type is converted to an imaginary type, the real part of the
complex value is discarded and the value of the imaginary part is converted according to
the conversion rules for the corresponding real types.
<a name="G.5" href="#G.5"><h3>G.5 Binary operators</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following subclauses supplement <a href="#6.5">6.5</a> in order to specify the type of the result for an
operation with an imaginary operand.
-<p><!--para 2-->
+<p><!--para 2 -->
For most operand types, the value of the result of a binary operator with an imaginary or
complex operand is completely determined, with reference to real arithmetic, by the usual
mathematical formula. For some operand types, the usual mathematical formula is
-<!--page 548 indent 4-->
+<!--page 548 -->
<a name="G.5.1" href="#G.5.1"><h4>G.5.1 Multiplicative operators</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
If one operand has real type and the other operand has imaginary type, then the result has
imaginary type. If both operands have imaginary type, then the result has real type. (If
either operand has complex type, then the result has complex type.)
-<p><!--para 2-->
+<p><!--para 2 -->
If the operands are not both complex, then the result and floating-point exception
behavior of the * operator is defined by the usual mathematical formula:
<pre>
<pre>
iy i(yu) -yv (-yv) + i(yu)</pre>
-<p><!--para 3-->
+<p><!--para 3 -->
<pre>
x + iy (xu) + i(yu) (-yv) + i(xv)</pre>
If the second operand is not complex, then the result and floating-point exception
<pre>
iy i(y/u) y/v</pre>
-<p><!--para 4-->
+<p><!--para 4 -->
<pre>
x + iy (x/u) + i(y/u) (y/v) + i(-x/v)</pre>
The * and / operators satisfy the following infinity properties for all real, imaginary, and
-<!--page 549 indent 4-->
+<!--page 549 -->
<li> if the first operand is a nonzero finite number or an infinity and the second operand is
a zero, then the result of the / operator is an infinity.
</ul>
-<p><!--para 5-->
+<p><!--para 5 -->
If both operands of the * operator are complex or if the second operand of the / operator
is complex, the operator raises floating-point exceptions if appropriate for the calculation
of the parts of the result, and may raise spurious floating-point exceptions.
-<p><!--para 6-->
+<p><!--para 6 -->
EXAMPLE 1 Multiplication of double _Complex operands could be implemented as follows. Note
that the imaginary unit I has imaginary type (see <a href="#G.6">G.6</a>).
-<!--page 550 indent 4-->
-<p><!--para 7-->
+<!--page 550 -->
+<p><!--para 7 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.3"><complex.h></a>
This implementation achieves the required treatment of infinities at the cost of only one isnan test in
ordinary (finite) cases. It is less than ideal in that undue overflow and underflow may occur.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 2 Division of two double _Complex operands could be implemented as follows.
-<!--page 551 indent 4-->
-<p><!--para 9-->
+<!--page 551 -->
+<p><!--para 9 -->
<pre>
#include <a href="#7.12"><math.h></a>
#include <a href="#7.3"><complex.h></a>
<a name="G.5.2" href="#G.5.2"><h4>G.5.2 Additive operators</h4></a>
<h6>Semantics</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
If both operands have imaginary type, then the result has imaginary type. (If one operand
has real type and the other operand has imaginary type, or if either operand has complex
type, then the result has complex type.)
-<p><!--para 2-->
+<p><!--para 2 -->
In all cases the result and floating-point exception behavior of a + or - operator is defined
by the usual mathematical formula:
<pre>
x + iy (x (+-) u) + iy x + i(y (+-) v) (x (+-) u) + i(y (+-) v)</pre>
<a name="G.6" href="#G.6"><h3>G.6 Complex arithmetic <complex.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The macros
<pre>
imaginary</pre>
is defined to be _Imaginary_I (not _Complex_I as stated in <a href="#7.3">7.3</a>). Notwithstanding
the provisions of <a href="#7.1.3">7.1.3</a>, a program may undefine and then perhaps redefine the macro
imaginary.
-<p><!--para 2-->
+<p><!--para 2 -->
This subclause contains specifications for the <a href="#7.3"><complex.h></a> functions that are
particularly suited to IEC 60559 implementations. For families of functions, the
specifications apply to all of the functions even though only the principal function is
-<!--page 552 indent 4-->
+<!--page 552 -->
shown. Unless otherwise specified, where the symbol ''(+-)'' occurs in both an argument
and the result, the result has the same sign as the argument.
-<p><!--para 3-->
+<p><!--para 3 -->
The functions are continuous onto both sides of their branch cuts, taking into account the
sign of zero. For example, csqrt(-2 (+-) i0) = (+-)i(sqrt)2. -
-<p><!--para 4-->
+<p><!--para 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.10.<sup><a href="#note365"><b>365)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 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.
-<p><!--para 6-->
+<p><!--para 6 -->
Each of the functions cabs and carg is specified by a formula in terms of a real
function (whose special cases are covered in <a href="#F">annex F</a>):
-<p><!--para 7-->
+<p><!--para 7 -->
<pre>
cabs(x + iy) = hypot(x, y)
carg(x + iy) = atan2(y, x)</pre>
Each of the functions casin, catan, ccos, csin, and ctan is specified implicitly by
a formula in terms of other complex functions (whose special cases are specified below):
-<p><!--para 8-->
+<p><!--para 8 -->
<pre>
casin(z) = -i casinh(iz)
catan(z) = -i catanh(iz)
specifications for the upper half-plane imply the specifications for the lower half-plane; if
the function f is also either even, f (-z) = f (z), or odd, f (-z) = - f (z), then the
specifications for the first quadrant imply the specifications for the other three quadrants.
-<p><!--para 9-->
+<p><!--para 9 -->
In the following subclauses, cis(y) is defined as cos(y) + i sin(y).
-<!--page 553 indent 4-->
+<!--page 553 -->
<h6>footnotes</h6>
<p><small><a name="note365" href="#note365">365)</a> As noted in <a href="#G.3">G.3</a>, a complex value with at least one infinite part is regarded as an infinity even if its
<a name="G.6.1" href="#G.6.1"><h4>G.6.1 Trigonometric functions</h4></a>
<a name="G.6.1.1" href="#G.6.1.1"><h5>G.6.1.1 The cacos functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cacos(conj(z)) = conj(cacos(z)).
<li> cacos((+-)0 + i0) returns pi /2 - i0.
<a name="G.6.2" href="#G.6.2"><h4>G.6.2 Hyperbolic functions</h4></a>
<a name="G.6.2.1" href="#G.6.2.1"><h5>G.6.2.1 The cacosh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cacosh(conj(z)) = conj(cacosh(z)).
<li> cacosh((+-)0 + i0) returns +0 + ipi /2.
<li> cacosh(-(inf) + i (inf)) returns +(inf) + i3pi /4.
<li> cacosh(+(inf) + i (inf)) returns +(inf) + ipi /4.
<li> cacosh((+-)(inf) + iNaN) returns +(inf) + iNaN.
-<!--page 554 indent 4-->
+<!--page 554 -->
<li> cacosh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid''
floating-point exception, for finite y.
<li> cacosh(NaN + i (inf)) returns +(inf) + iNaN.
</ul>
<a name="G.6.2.2" href="#G.6.2.2"><h5>G.6.2.2 The casinh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> casinh(conj(z)) = conj(casinh(z)) and casinh is odd.
<li> casinh(+0 + i0) returns 0 + i0.
</ul>
<a name="G.6.2.3" href="#G.6.2.3"><h5>G.6.2.3 The catanh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> catanh(conj(z)) = conj(catanh(z)) and catanh is odd.
<li> catanh(+0 + i0) returns +0 + i0.
<li> catanh(+(inf) + iy) returns +0 + ipi /2, for finite positive-signed y.
<li> catanh(+(inf) + i (inf)) returns +0 + ipi /2.
<li> catanh(+(inf) + iNaN) returns +0 + iNaN.
-<!--page 555 indent 4-->
+<!--page 555 -->
<li> catanh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid''
floating-point exception, for finite y.
<li> catanh(NaN + i (inf)) returns (+-)0 + ipi /2 (where the sign of the real part of the result is
</ul>
<a name="G.6.2.4" href="#G.6.2.4"><h5>G.6.2.4 The ccosh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> ccosh(conj(z)) = conj(ccosh(z)) and ccosh is even.
<li> ccosh(+0 + i0) returns 1 + i0.
</ul>
<a name="G.6.2.5" href="#G.6.2.5"><h5>G.6.2.5 The csinh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> csinh(conj(z)) = conj(csinh(z)) and csinh is odd.
<li> csinh(+0 + i0) returns +0 + i0.
unspecified) and raises the ''invalid'' floating-point exception.
<li> csinh(+0 + iNaN) returns (+-)0 + iNaN (where the sign of the real part of the result is
unspecified).
-<!--page 556 indent 4-->
+<!--page 556 -->
<li> csinh(x + i (inf)) returns NaN + iNaN and raises the ''invalid'' floating-point
exception, for positive finite x.
<li> csinh(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
</ul>
<a name="G.6.2.6" href="#G.6.2.6"><h5>G.6.2.6 The ctanh functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> ctanh(conj(z)) = conj(ctanh(z))and ctanh is odd.
<li> ctanh(+0 + i0) returns +0 + i0.
<li> ctanh(NaN + iy) returns NaN + iNaN and optionally raises the ''invalid'' floating-
point exception, for all nonzero numbers y.
<li> ctanh(NaN + iNaN) returns NaN + iNaN.
-<!--page 557 indent 4-->
+<!--page 557 -->
</ul>
<a name="G.6.3" href="#G.6.3"><h4>G.6.3 Exponential and logarithmic functions</h4></a>
<a name="G.6.3.1" href="#G.6.3.1"><h5>G.6.3.1 The cexp functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> cexp(conj(z)) = conj(cexp(z)).
<li> cexp((+-)0 + i0) returns 1 + i0.
</ul>
<a name="G.6.3.2" href="#G.6.3.2"><h5>G.6.3.2 The clog functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> clog(conj(z)) = conj(clog(z)).
<li> clog(-0 + i0) returns -(inf) + ipi and raises the ''divide-by-zero'' floating-point
<li> clog(x + i (inf)) returns +(inf) + ipi /2, for finite x.
<li> clog(x + iNaN) returns NaN + iNaN and optionally raises the ''invalid'' floating-
point exception, for finite x.
-<!--page 558 indent 4-->
+<!--page 558 -->
<li> clog(-(inf) + iy) returns +(inf) + ipi , for finite positive-signed y.
<li> clog(+(inf) + iy) returns +(inf) + i0, for finite positive-signed y.
<li> clog(-(inf) + i (inf)) returns +(inf) + i3pi /4.
<a name="G.6.4" href="#G.6.4"><h4>G.6.4 Power and absolute-value functions</h4></a>
<a name="G.6.4.1" href="#G.6.4.1"><h5>G.6.4.1 The cpow functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The cpow functions raise floating-point exceptions if appropriate for the calculation of
the parts of the result, and may also raise spurious floating-point exceptions.<sup><a href="#note366"><b>366)</b></a></sup>
</small>
<a name="G.6.4.2" href="#G.6.4.2"><h5>G.6.4.2 The csqrt functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> csqrt(conj(z)) = conj(csqrt(z)).
<li> csqrt((+-)0 + i0) returns +0 + i0.
-<!--page 559 indent 4-->
+<!--page 559 -->
</ul>
<a name="G.7" href="#G.7"><h3>G.7 Type-generic math <tgmath.h></h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Type-generic macros that accept complex arguments also accept imaginary arguments. If
an argument is imaginary, the macro expands to an expression whose type is real,
imaginary, or complex, as appropriate for the particular function: if the argument is
imaginary, then the types of cos, cosh, fabs, carg, cimag, and creal are real; the
types of sin, tan, sinh, tanh, asin, atan, asinh, and atanh are imaginary; and
the types of the others are complex.
-<p><!--para 2-->
+<p><!--para 2 -->
Given an imaginary argument, each of the type-generic macros cos, sin, tan, cosh,
sinh, tanh, asin, atan, asinh, atanh is specified by a formula in terms of real
functions:
-<!--page 560 indent 4-->
+<!--page 560 -->
<pre>
cos(iy) = cosh(y)
sin(iy) = i sinh(y)
Language independent arithmetic</pre>
<a name="H.1" href="#H.1"><h3>H.1 Introduction</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This annex documents the extent to which the C language supports the ISO/IEC 10967-1
standard for language-independent arithmetic (LIA-1). LIA-1 is more general than
IEC 60559 (<a href="#F">annex F</a>) in that it covers integer and diverse floating-point arithmetics.
<a name="H.2" href="#H.2"><h3>H.2 Types</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The relevant C arithmetic types meet the requirements of LIA-1 types if an
implementation adds notification of exceptional arithmetic operations and meets the 1
unit in the last place (ULP) accuracy requirement (LIA-1 subclause <a href="#5.2.8">5.2.8</a>).
<a name="H.2.1" href="#H.2.1"><h4>H.2.1 Boolean type</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The LIA-1 data type Boolean is implemented by the C data type bool with values of
true and false, all from <a href="#7.18"><stdbool.h></a>.
<a name="H.2.2" href="#H.2.2"><h4>H.2.2 Integer types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The signed C integer types int, long int, long long int, and the corresponding
unsigned types are compatible with LIA-1. If an implementation adds support for the
LIA-1 exceptional values ''integer_overflow'' and ''undefined'', then those types are
in that overflows or out-of-bounds results silently wrap. An implementation that defines
signed integer types as also being modulo need not detect integer overflow, in which case,
only integer divide-by-zero need be detected.
-<p><!--para 2-->
+<p><!--para 2 -->
The parameters for the integer data types can be accessed by the following:
maxint INT_MAX, LONG_MAX, LLONG_MAX, UINT_MAX, ULONG_MAX,
<pre>
ULLONG_MAX</pre>
minint INT_MIN, LONG_MIN, LLONG_MIN
-<p><!--para 3-->
+<p><!--para 3 -->
The parameter ''bounded'' is always true, and is not provided. The parameter ''minint''
is always 0 for the unsigned types, and is not provided for those types.
-<!--page 561 indent 4-->
+<!--page 561 -->
<a name="H.2.2.1" href="#H.2.2.1"><h5>H.2.2.1 Integer operations</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The integer operations on integer types are the following:
addI x + y
subI x - y
where x and y are expressions of the same integer type.
<a name="H.2.3" href="#H.2.3"><h4>H.2.3 Floating-point types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The C floating-point types float, double, and long double are compatible with
LIA-1. If an implementation adds support for the LIA-1 exceptional values
''underflow'', ''floating_overflow'', and ''"undefined'', then those types are conformant
conformant types.
<a name="H.2.3.1" href="#H.2.3.1"><h5>H.2.3.1 Floating-point parameters</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The parameters for a floating point data type can be accessed by the following:
r FLT_RADIX
p FLT_MANT_DIG, DBL_MANT_DIG, LDBL_MANT_DIG
emax FLT_MAX_EXP, DBL_MAX_EXP, LDBL_MAX_EXP
emin FLT_MIN_EXP, DBL_MIN_EXP, LDBL_MIN_EXP
-<p><!--para 2-->
+<p><!--para 2 -->
The derived constants for the floating point types are accessed by the following:
-<!--page 562 indent 4-->
+<!--page 562 -->
fmax FLT_MAX, DBL_MAX, LDBL_MAX
fminN FLT_MIN, DBL_MIN, LDBL_MIN
epsilon FLT_EPSILON, DBL_EPSILON, LDBL_EPSILON
rnd_style FLT_ROUNDS
<a name="H.2.3.2" href="#H.2.3.2"><h5>H.2.3.2 Floating-point operations</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The floating-point operations on floating-point types are the following:
addF x + y
subF x - y
is of type long int.
<a name="H.2.3.3" href="#H.2.3.3"><h5>H.2.3.3 Rounding styles</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The C Standard requires all floating types to use the same radix and rounding style, so
that only one identifier for each is provided to map to LIA-1.
-<p><!--para 2-->
+<p><!--para 2 -->
The FLT_ROUNDS parameter can be used to indicate the LIA-1 rounding styles:
truncate FLT_ROUNDS == 0
-<!--page 563 indent 4-->
+<!--page 563 -->
nearest FLT_ROUNDS == 1
other FLT_ROUNDS != 0 && FLT_ROUNDS != 1
provided that an implementation extends FLT_ROUNDS to cover the rounding style used
in all relevant LIA-1 operations, not just addition as in C.
<a name="H.2.4" href="#H.2.4"><h4>H.2.4 Type conversions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The LIA-1 type conversions are the following type casts:
cvtI' -> I (int)i, (long int)i, (long long int)i,
<pre>
(unsigned long long int)x</pre>
cvtI -> F (float)i, (double)i, (long double)i
cvtF' -> F (float)x, (double)x, (long double)x
-<p><!--para 2-->
+<p><!--para 2 -->
In the above conversions from floating to integer, the use of (cast)x can be replaced with
(cast)round(x), (cast)rint(x), (cast)nearbyint(x), (cast)trunc(x),
(cast)ceil(x), or (cast)floor(x). In addition, C's floating-point to integer
conversion functions, lrint(), llrint(), lround(), and llround(), can be
used. They all meet LIA-1's requirements on floating to integer rounding for in-range
values. For out-of-range values, the conversions shall silently wrap for the modulo types.
-<p><!--para 3-->
+<p><!--para 3 -->
The fmod() function is useful for doing silent wrapping to unsigned integer types, e.g.,
fmod( fabs(rint(x)), 65536.0 ) or (0.0 <= (y = fmod( rint(x),
65536.0 )) ? y : 65536.0 + y) will compute an integer value in the range 0.0
e.g., remainder( rint(x), 65536.0 ) will compute an integer value in the
range -32767.0 to +32768.0 which is not, in general, in the range of signed short
int.
-<p><!--para 4-->
+<p><!--para 4 -->
C's conversions (casts) from floating-point to floating-point can meet LIA-1
requirements if an implementation uses round-to-nearest (IEC 60559 default).
-<p><!--para 5-->
+<p><!--para 5 -->
C's conversions (casts) from integer to floating-point can meet LIA-1 requirements if an
implementation uses round-to-nearest.
-<!--page 564 indent 4-->
+<!--page 564 -->
<a name="H.3" href="#H.3"><h3>H.3 Notification</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Notification is the process by which a user or program is informed that an exceptional
arithmetic operation has occurred. C's operations are compatible with LIA-1 in that C
allows an implementation to cause a notification to occur when any arithmetic operation
returns an exceptional value as defined in LIA-1 clause 5.
<a name="H.3.1" href="#H.3.1"><h4>H.3.1 Notification alternatives</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
LIA-1 requires at least the following two alternatives for handling of notifications:
setting indicators or trap-and-terminate. LIA-1 allows a third alternative: trap-and-
resume.
-<p><!--para 2-->
+<p><!--para 2 -->
An implementation need only support a given notification alternative for the entire
program. An implementation may support the ability to switch between notification
alternatives during execution, but is not required to do so. An implementation can
provide separate selection for each kind of notification, but this is not required.
-<p><!--para 3-->
+<p><!--para 3 -->
C allows an implementation to provide notification. C's SIGFPE (for traps) and
FE_INVALID, FE_DIVBYZERO, FE_OVERFLOW, FE_UNDERFLOW (for indicators)
can provide LIA-1 notification.
-<p><!--para 4-->
+<p><!--para 4 -->
C's signal handlers are compatible with LIA-1. Default handling of SIGFPE can
provide trap-and-terminate behavior, except for those LIA-1 operations implemented by
math library function calls. User-provided signal handlers for SIGFPE allow for trap-
and-resume behavior with the same constraint.
<a name="H.3.1.1" href="#H.3.1.1"><h5>H.3.1.1 Indicators</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
C's <a href="#7.6"><fenv.h></a> status flags are compatible with the LIA-1 indicators.
-<p><!--para 2-->
+<p><!--para 2 -->
The following mapping is for floating-point types:
undefined FE_INVALID, FE_DIVBYZERO
floating_overflow FE_OVERFLOW
underflow FE_UNDERFLOW
-<p><!--para 3-->
+<p><!--para 3 -->
The floating-point indicator interrogation and manipulation operations are:
set_indicators feraiseexcept(i)
clear_indicators feclearexcept(i)
test_indicators fetestexcept(i)
current_indicators fetestexcept(FE_ALL_EXCEPT)
where i is an expression of type int representing a subset of the LIA-1 indicators.
-<p><!--para 4-->
+<p><!--para 4 -->
C allows an implementation to provide the following LIA-1 required behavior: at
program termination if any indicator is set the implementation shall send an unambiguous
-<!--page 565 indent 4-->
+<!--page 565 -->
and ''hard to ignore'' message (see LIA-1 subclause <a href="#6.1.2">6.1.2</a>)
-<p><!--para 5-->
+<p><!--para 5 -->
LIA-1 does not make the distinction between floating-point and integer for ''undefined''.
This documentation makes that distinction because <a href="#7.6"><fenv.h></a> covers only the floating-
point indicators.
<a name="H.3.1.2" href="#H.3.1.2"><h5>H.3.1.2 Traps</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
C is compatible with LIA-1's trap requirements for arithmetic operations, but not for
math library functions (which are not permitted to invoke a user's signal handler for
SIGFPE). An implementation can provide an alternative of notification through
termination with a ''hard-to-ignore'' message (see LIA-1 subclause <a href="#6.1.3">6.1.3</a>).
-<p><!--para 2-->
+<p><!--para 2 -->
LIA-1 does not require that traps be precise.
-<p><!--para 3-->
+<p><!--para 3 -->
C does require that SIGFPE be the signal corresponding to LIA-1 arithmetic exceptions,
if there is any signal raised for them.
-<p><!--para 4-->
+<p><!--para 4 -->
C supports signal handlers for SIGFPE and allows trapping of LIA-1 arithmetic
exceptions. When LIA-1 arithmetic exceptions do trap, C's signal-handler mechanism
allows trap-and-terminate (either default implementation behavior or user replacement for
it) or trap-and-resume, at the programmer's option.
-<!--page 566 indent 4-->
+<!--page 566 -->
<a name="I" href="#I"><h2>Annex I</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Common warnings</pre>
An implementation may generate warnings in many situations, none of which are
specified as part of this International Standard. The following are a few of the more
common situations.
-<p><!--para 2-->
+<p><!--para 2 -->
<ul>
<li> A new struct or union type appears in a function prototype (<a href="#6.2.1">6.2.1</a>, <a href="#6.7.2.3">6.7.2.3</a>).
<li> A block with initialization of an object that has automatic storage duration is jumped
<li> A statement with no apparent effect is encountered (<a href="#6.8">6.8</a>).
<li> A constant expression is used as the controlling expression of a selection statement
(<a href="#6.8.4">6.8.4</a>).
-<!--page 567 indent 0-->
+<!--page 567 -->
<li> An incorrectly formed preprocessing group is encountered while skipping a
preprocessing group (<a href="#6.10.1">6.10.1</a>).
<li> An unrecognized #pragma directive is encountered (<a href="#6.10.6">6.10.6</a>).
-<!--page 568 indent 4-->
+<!--page 568 -->
</ul>
<a name="J" href="#J"><h2>Annex J</h2></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
(informative)
Portability issues</pre>
Standard.
<a name="J.1" href="#J.1"><h3>J.1 Unspecified behavior</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following are unspecified:
<ul>
<li> The manner and timing of static initialization (<a href="#5.1.2">5.1.2</a>).
<li> Whether two string literals result in distinct arrays (<a href="#6.4.5">6.4.5</a>).
<li> The order in which subexpressions are evaluated and the order in which side effects
take place, except as specified for the function-call (), &&, ||, ? :, and comma
-<!--page 569 indent 0-->
+<!--page 569 -->
operators (<a href="#6.5">6.5</a>).
<li> The order in which the function designator, arguments, and subexpressions within the
arguments are evaluated in a function call (<a href="#6.5.2.2">6.5.2.2</a>).
<li> The numeric result of the ilogb functions when the correct value is outside the
range of the return type (<a href="#7.12.6.5">7.12.6.5</a>, <a href="#F.10.3.5">F.10.3.5</a>).
<li> The result of rounding when the value is out of range (<a href="#7.12.9.5">7.12.9.5</a>, <a href="#7.12.9.7">7.12.9.7</a>, <a href="#F.10.6.5">F.10.6.5</a>).
-<!--page 570 indent 0-->
+<!--page 570 -->
<li> The value stored by the remquo functions in the object pointed to by quo when y is
zero (<a href="#7.12.10.3">7.12.10.3</a>).
<li> Whether a comparison macro argument that is represented in a format wider than its
<a href="#7.28.6.4.2">7.28.6.4.2</a>,
<li> The resulting value when the ''invalid'' floating-point exception is raised during
IEC 60559 floating to integer conversion (<a href="#F.4">F.4</a>).
-<!--page 571 indent 4-->
+<!--page 571 -->
<li> Whether conversion of non-integer IEC 60559 floating values to integer raises the
''inexact'' floating-point exception (<a href="#F.4">F.4</a>).
<li> Whether or when library functions in <a href="#7.12"><math.h></a> raise the ''inexact'' floating-point
</ul>
<a name="J.2" href="#J.2"><h3>J.2 Undefined behavior</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior is undefined in the following circumstances:
<ul>
<li> A ''shall'' or ''shall not'' requirement that appears outside of a constraint is violated
<li> The same identifier has both internal and external linkage in the same translation unit
(<a href="#6.2.2">6.2.2</a>).
<li> An object is referred to outside of its lifetime (<a href="#6.2.4">6.2.4</a>).
-<!--page 572 indent 0-->
+<!--page 572 -->
<li> The value of a pointer to an object whose lifetime has ended is used (<a href="#6.2.4">6.2.4</a>).
<li> The value of an object with automatic storage duration is used while it is
indeterminate (<a href="#6.2.4">6.2.4</a>, <a href="#6.7.9">6.7.9</a>, <a href="#6.8">6.8</a>).
(<a href="#6.3.2.3">6.3.2.3</a>).
<li> A pointer is used to call a function whose type is not compatible with the referenced
type (<a href="#6.3.2.3">6.3.2.3</a>).
-<!--page 573 indent 0-->
+<!--page 573 -->
<li> An unmatched ' or " character is encountered on a logical source line during
tokenization (<a href="#6.4">6.4</a>).
<li> A reserved keyword token is used in translation phase 7 or 8 for some purpose other
expression) pointed to by the expression that denotes the called function (<a href="#6.5.2.2">6.5.2.2</a>).
<li> A member of an atomic structure or union is accessed (<a href="#6.5.2.3">6.5.2.3</a>).
<li> The operand of the unary * operator has an invalid value (<a href="#6.5.3.2">6.5.3.2</a>).
-<!--page 574 indent 0-->
+<!--page 574 -->
<li> A pointer is converted to other than an integer or pointer type (<a href="#6.5.4">6.5.4</a>).
<li> The value of the second operand of the / or % operator is zero (<a href="#6.5.5">6.5.5</a>).
<li> Addition or subtraction of a pointer into, or just beyond, an array object and an
<li> An arithmetic constant expression does not have arithmetic type; has operands that
are not integer constants, floating constants, enumeration constants, character
constants, or sizeof expressions; or contains casts (outside operands to sizeof
-<!--page 575 indent 0-->
+<!--page 575 -->
operators) other than conversions of arithmetic types to arithmetic types (<a href="#6.6">6.6</a>).
<li> The value of an object is accessed by an array-subscript [], member-access . or ->,
address &, or indirection * operator or a pointer cast in creating an address constant
<li> A function declared with a _Noreturn function specifier returns to its caller (<a href="#6.7.4">6.7.4</a>).
<li> The definition of an object has an alignment specifier and another declaration of that
object has a different alignment specifier (<a href="#6.7.5">6.7.5</a>).
-<!--page 576 indent 0-->
+<!--page 576 -->
<li> Declarations of an object in different translation units have different alignment
specifiers (<a href="#6.7.5">6.7.5</a>).
<li> Two pointer types that are required to be compatible are not identically qualified, or
(<a href="#6.9.1">6.9.1</a>).
<li> A function that accepts a variable number of arguments is defined without a
parameter type list that ends with the ellipsis notation (<a href="#6.9.1">6.9.1</a>).
-<!--page 577 indent 0-->
+<!--page 577 -->
<li> The } that terminates a function is reached, and the value of the function call is used
by the caller (<a href="#6.9.1">6.9.1</a>).
<li> An identifier for an object with internal linkage and an incomplete type is declared
<li> A function, object, type, or macro that is specified as being declared or defined by
some standard header is used before any header that declares or defines it is included
(<a href="#7.1.2">7.1.2</a>).
-<!--page 578 indent 0-->
+<!--page 578 -->
<li> A standard header is included while a macro is defined with the same name as a
keyword (<a href="#7.1.2">7.1.2</a>).
<li> The program attempts to declare a library function itself, rather than via a standard
fegetenv or feholdexcept, nor is it an environment macro (<a href="#7.6.4.3">7.6.4.3</a>, <a href="#7.6.4.4">7.6.4.4</a>).
<li> The value of the result of an integer arithmetic or conversion function cannot be
represented (<a href="#7.8.2.1">7.8.2.1</a>, <a href="#7.8.2.2">7.8.2.2</a>, <a href="#7.8.2.3">7.8.2.3</a>, <a href="#7.8.2.4">7.8.2.4</a>, <a href="#7.22.6.1">7.22.6.1</a>, <a href="#7.22.6.2">7.22.6.2</a>, <a href="#7.22.1">7.22.1</a>).
-<!--page 579 indent 0-->
+<!--page 579 -->
<li> The program modifies the string pointed to by the value returned by the setlocale
function (<a href="#7.11.1.1">7.11.1.1</a>).
<li> The program modifies the structure pointed to by the value returned by the
<li> A function with a variable number of arguments attempts to access its varying
arguments other than through a properly declared and initialized va_list object, or
before the va_start macro is invoked (<a href="#7.16">7.16</a>, <a href="#7.16.1.1">7.16.1.1</a>, <a href="#7.16.1.4">7.16.1.4</a>).
-<!--page 580 indent 0-->
+<!--page 580 -->
<li> The macro va_arg is invoked using the parameter ap that was passed to a function
that invoked the macro va_arg with the same parameter (<a href="#7.16">7.16</a>).
<li> A macro definition of va_start, va_arg, va_copy, or va_end is suppressed in
exactly match one of the specified character sequences (<a href="#7.21.5.3">7.21.5.3</a>).
<li> An output operation on an update stream is followed by an input operation without an
intervening call to the fflush function or a file positioning function, or an input
-<!--page 581 indent 0-->
+<!--page 581 -->
operation on an update stream is followed by an output operation with an intervening
call to a file positioning function (<a href="#7.21.5.3">7.21.5.3</a>).
<li> An attempt is made to use the contents of the array that was supplied in a call to the
<a href="#7.26.3.5">7.26.3.5</a>, <a href="#7.28.2.1">7.28.2.1</a>, <a href="#7.28.2.2">7.28.2.2</a>, <a href="#7.28.5.1">7.28.5.1</a>).
<li> The number of characters transmitted by a formatted output function is greater than
INT_MAX (<a href="#7.21.6.1">7.21.6.1</a>, <a href="#7.21.6.3">7.21.6.3</a>, <a href="#7.21.6.8">7.21.6.8</a>, <a href="#7.21.6.10">7.21.6.10</a>).
-<!--page 582 indent 0-->
+<!--page 582 -->
<li> The result of a conversion by one of the formatted input functions cannot be
represented in the corresponding object, or the receiving object does not have an
appropriate type (<a href="#7.21.6.2">7.21.6.2</a>, <a href="#7.28.2.2">7.28.2.2</a>).
with a zero requested size is used to access an object (<a href="#7.22.3">7.22.3</a>).
<li> The value of a pointer that refers to space deallocated by a call to the free or
realloc function is used (<a href="#7.22.3">7.22.3</a>).
-<!--page 583 indent 0-->
+<!--page 583 -->
<li> The alignment requested of the aligned_alloc function is not valid or not
supported by the implementation, or the size requested is not an integral multiple of
the alignment (<a href="#7.22.3.1">7.22.3.1</a>).
strftime, wcsxfrm, or wcsftime function in which the specified length was
too small to hold the entire null-terminated result (<a href="#7.23.4.5">7.23.4.5</a>, <a href="#7.26.3.5">7.26.3.5</a>, <a href="#7.28.4.4.4">7.28.4.4.4</a>,
<a href="#7.28.5.1">7.28.5.1</a>).
-<!--page 584 indent 4-->
+<!--page 584 -->
<li> The first argument in the very first call to the strtok or wcstok is a null pointer
(<a href="#7.23.5.8">7.23.5.8</a>, <a href="#7.28.4.5.7">7.28.4.5.7</a>).
<li> The type of an argument to a type-generic macro is not compatible with the type of
</ul>
<a name="J.3" href="#J.3"><h3>J.3 Implementation-defined behavior</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A conforming implementation is required to document its choice of behavior in each of
the areas listed in this subclause. The following are implementation-defined:
-<!--page 585 indent 4-->
+<!--page 585 -->
<a name="J.3.1" href="#J.3.1"><h4>J.3.1 Translation</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> How a diagnostic is identified (<a href="#3.10">3.10</a>, <a href="#5.1.1.3">5.1.1.3</a>).
<li> Whether each nonempty sequence of white-space characters other than new-line is
</ul>
<a name="J.3.2" href="#J.3.2"><h4>J.3.2 Environment</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The mapping between physical source file multibyte characters and the source
character set in translation phase 1 (<a href="#5.1.1.2">5.1.1.2</a>).
</ul>
<a name="J.3.3" href="#J.3.3"><h4>J.3.3 Identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> Which additional multibyte characters may appear in identifiers and their
correspondence to universal character names (<a href="#6.4.2">6.4.2</a>).
<li> The number of significant initial characters in an identifier (<a href="#5.2.4.1">5.2.4.1</a>, <a href="#6.4.2">6.4.2</a>).
-<!--page 586 indent 4-->
+<!--page 586 -->
</ul>
<a name="J.3.4" href="#J.3.4"><h4>J.3.4 Characters</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The number of bits in a byte (<a href="#3.6">3.6</a>).
<li> The values of the members of the execution character set (<a href="#5.2.1">5.2.1</a>).
<li> The encoding of any of wchar_t, char16_t, and char32_t where the
corresponding standard encoding macro (__STDC_ISO_10646__,
__STDC_UTF_16__, or __STDC_UTF_32__) is not defined (<a href="#6.10.8.2">6.10.8.2</a>).
-<!--page 587 indent 4-->
+<!--page 587 -->
</ul>
<a name="J.3.5" href="#J.3.5"><h4>J.3.5 Integers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> Any extended integer types that exist in the implementation (<a href="#6.2.5">6.2.5</a>).
<li> Whether signed integer types are represented using sign and magnitude, two's
</ul>
<a name="J.3.6" href="#J.3.6"><h4>J.3.6 Floating point</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The accuracy of the floating-point operations and of the library functions in
<a href="#7.12"><math.h></a> and <a href="#7.3"><complex.h></a> that return floating-point results (<a href="#5.2.4.2.2">5.2.4.2.2</a>).
<li> Additional floating-point exceptions, rounding modes, environments, and
classifications, and their macro names (<a href="#7.6">7.6</a>, <a href="#7.12">7.12</a>).
<li> The default state for the FP_CONTRACT pragma (<a href="#7.12.2">7.12.2</a>).
-<!--page 588 indent 4-->
+<!--page 588 -->
</ul>
<a name="J.3.7" href="#J.3.7"><h4>J.3.7 Arrays and pointers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The result of converting a pointer to an integer or vice versa (<a href="#6.3.2.3">6.3.2.3</a>).
<li> The size of the result of subtracting two pointers to elements of the same array
</ul>
<a name="J.3.8" href="#J.3.8"><h4>J.3.8 Hints</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The extent to which suggestions made by using the register storage-class
specifier are effective (<a href="#6.7.1">6.7.1</a>).
</ul>
<a name="J.3.9" href="#J.3.9"><h4>J.3.9 Structures, unions, enumerations, and bit-fields</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> Whether a ''plain'' int bit-field is treated as a signed int bit-field or as an
unsigned int bit-field (<a href="#6.7.2">6.7.2</a>, <a href="#6.7.2.1">6.7.2.1</a>).
</ul>
<a name="J.3.10" href="#J.3.10"><h4>J.3.10 Qualifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> What constitutes an access to an object that has volatile-qualified type (<a href="#6.7.3">6.7.3</a>).
</ul>
<a name="J.3.11" href="#J.3.11"><h4>J.3.11 Preprocessing directives</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The locations within #pragma directives where header name preprocessing tokens
are recognized (<a href="#6.4">6.4</a>, <a href="#6.4.7">6.4.7</a>).
execution character set (<a href="#6.10.1">6.10.1</a>).
<li> Whether the value of a single-character character constant in a constant expression
that controls conditional inclusion may have a negative value (<a href="#6.10.1">6.10.1</a>).
-<!--page 589 indent 4-->
+<!--page 589 -->
<li> The places that are searched for an included < > delimited header, and how the places
are specified or the header is identified (<a href="#6.10.2">6.10.2</a>).
<li> How the named source file is searched for in an included " " delimited header
</ul>
<a name="J.3.12" href="#J.3.12"><h4>J.3.12 Library functions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> Any library facilities available to a freestanding program, other than the minimal set
required by clause 4 (<a href="#5.1.2.1">5.1.2.1</a>).
math_errhandling & MATH_ERRNO is nonzero, and whether the ''underflow''
floating-point exception is raised when the integer expression math_errhandling
& MATH_ERREXCEPT is nonzero. (<a href="#7.12.1">7.12.1</a>).
-<!--page 590 indent 0-->
+<!--page 590 -->
<li> Whether a domain error occurs or zero is returned when an fmod function has a
second argument of zero (<a href="#7.12.10.1">7.12.10.1</a>).
<li> Whether a domain error occurs or zero is returned when a remainder function has
(<a href="#7.21.4.3">7.21.4.3</a>).
<li> Which changes of mode are permitted (if any), and under what circumstances
(<a href="#7.21.5.4">7.21.5.4</a>).
-<!--page 591 indent 0-->
+<!--page 591 -->
<li> The style used to print an infinity or NaN, and the meaning of any n-char or n-wchar
sequence printed for a NaN (<a href="#7.21.6.1">7.21.6.1</a>, <a href="#7.28.2.1">7.28.2.1</a>).
<li> The output for %p conversion in the fprintf or fwprintf function (<a href="#7.21.6.1">7.21.6.1</a>,
functions in the "C" locale (<a href="#7.26.3.5">7.26.3.5</a>, <a href="#7.28.5.1">7.28.5.1</a>).
<li> Whether the functions in <a href="#7.12"><math.h></a> honor the rounding direction mode in an
IEC 60559 conformant implementation, unless explicitly specified otherwise (<a href="#F.10">F.10</a>).
-<!--page 592 indent 4-->
+<!--page 592 -->
</ul>
<a name="J.3.13" href="#J.3.13"><h4>J.3.13 Architecture</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
<ul>
<li> The values or expressions assigned to the macros specified in the headers
<a href="#7.7"><float.h></a>, <a href="#7.10"><limits.h></a>, and <a href="#7.20"><stdint.h></a> (<a href="#5.2.4.2">5.2.4.2</a>, <a href="#7.20.2">7.20.2</a>, <a href="#7.20.3">7.20.3</a>).
</ul>
<a name="J.4" href="#J.4"><h3>J.4 Locale-specific behavior</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following characteristics of a hosted environment are locale-specific and are required
to be documented by the implementation:
<ul>
<li> Additional subject sequences accepted by the numeric conversion functions (<a href="#7.22.1">7.22.1</a>,
<a href="#7.28.4.1">7.28.4.1</a>).
<li> The collation sequence of the execution character set (<a href="#7.23.4.3">7.23.4.3</a>, <a href="#7.28.4.4.2">7.28.4.4.2</a>).
-<!--page 593 indent 4-->
+<!--page 593 -->
<li> The contents of the error message strings set up by the strerror function
(<a href="#7.23.6.2">7.23.6.2</a>).
<li> The formats for time and date (<a href="#7.26.3.5">7.26.3.5</a>, <a href="#7.28.5.1">7.28.5.1</a>).
</ul>
<a name="J.5" href="#J.5"><h3>J.5 Common extensions</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The following extensions are widely used in many systems, but are not portable to all
implementations. The inclusion of any extension that may cause a strictly conforming
program to become invalid renders an implementation nonconforming. Examples of such
predefined macros with names that do not begin with an underscore.
<a name="J.5.1" href="#J.5.1"><h4>J.5.1 Environment arguments</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
In a hosted environment, the main function receives a third argument, char *envp[],
that points to a null-terminated array of pointers to char, each of which points to a string
that provides information about the environment for this execution of the program
(<a href="#5.1.2.2.1">5.1.2.2.1</a>).
<a name="J.5.2" href="#J.5.2"><h4>J.5.2 Specialized identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Characters other than the underscore _, letters, and digits, that are not part of the basic
source character set (such as the dollar sign $, or characters in national character sets)
may appear in an identifier (<a href="#6.4.2">6.4.2</a>).
<a name="J.5.3" href="#J.5.3"><h4>J.5.3 Lengths and cases of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
All characters in identifiers (with or without external linkage) are significant (<a href="#6.4.2">6.4.2</a>).
<a name="J.5.4" href="#J.5.4"><h4>J.5.4 Scopes of identifiers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A function identifier, or the identifier of an object the declaration of which contains the
keyword extern, has file scope (<a href="#6.2.1">6.2.1</a>).
<a name="J.5.5" href="#J.5.5"><h4>J.5.5 Writable string literals</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
String literals are modifiable (in which case, identical string literals should denote distinct
objects) (<a href="#6.4.5">6.4.5</a>).
-<!--page 594 indent 4-->
+<!--page 594 -->
<a name="J.5.6" href="#J.5.6"><h4>J.5.6 Other arithmetic types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Additional arithmetic types, such as __int128 or double double, and their
appropriate conversions are defined (<a href="#6.2.5">6.2.5</a>, <a href="#6.3.1">6.3.1</a>). Additional floating types may have
more range or precision than long double, may be used for evaluating expressions of
other floating types, and may be used to define float_t or double_t.
<a name="J.5.7" href="#J.5.7"><h4>J.5.7 Function pointer casts</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A pointer to an object or to void may be cast to a pointer to a function, allowing data to
be invoked as a function (<a href="#6.5.4">6.5.4</a>).
-<p><!--para 2-->
+<p><!--para 2 -->
A pointer to a function may be cast to a pointer to an object or to void, allowing a
function to be inspected or modified (for example, by a debugger) (<a href="#6.5.4">6.5.4</a>).
<a name="J.5.8" href="#J.5.8"><h4>J.5.8 Extended bit-field types</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A bit-field may be declared with a type other than _Bool, unsigned int, or
signed int, with an appropriate maximum width (<a href="#6.7.2.1">6.7.2.1</a>).
<a name="J.5.9" href="#J.5.9"><h4>J.5.9 The fortran keyword</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The fortran function specifier may be used in a function declaration to indicate that
calls suitable for FORTRAN should be generated, or that a different representation for the
external name is to be generated (<a href="#6.7.4">6.7.4</a>).
<a name="J.5.10" href="#J.5.10"><h4>J.5.10 The asm keyword</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The asm keyword may be used to insert assembly language directly into the translator
output (<a href="#6.8">6.8</a>). The most common implementation is via a statement of the form:
<pre>
asm ( character-string-literal );</pre>
<a name="J.5.11" href="#J.5.11"><h4>J.5.11 Multiple external definitions</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
There may be more than one external definition for the identifier of an object, with or
without the explicit use of the keyword extern; if the definitions disagree, or more than
one is initialized, the behavior is undefined (<a href="#6.9.2">6.9.2</a>).
<a name="J.5.12" href="#J.5.12"><h4>J.5.12 Predefined macro names</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Macro names that do not begin with an underscore, describing the translation and
execution environments, are defined by the implementation before translation begins
(<a href="#6.10.8">6.10.8</a>).
-<!--page 595 indent 4-->
+<!--page 595 -->
<a name="J.5.13" href="#J.5.13"><h4>J.5.13 Floating-point status flags</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
If any floating-point status flags are set on normal termination after all calls to functions
registered by the atexit function have been made (see <a href="#7.22.4.4">7.22.4.4</a>), the implementation
writes some diagnostics indicating the fact to the stderr stream, if it is still open,
<a name="J.5.14" href="#J.5.14"><h4>J.5.14 Extra arguments for signal handlers</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Handlers for specific signals are called with extra arguments in addition to the signal
number (<a href="#7.14.1.1">7.14.1.1</a>).
<a name="J.5.15" href="#J.5.15"><h4>J.5.15 Additional stream types and file-opening modes</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Additional mappings from files to streams are supported (<a href="#7.21.2">7.21.2</a>).
-<p><!--para 2-->
+<p><!--para 2 -->
Additional file-opening modes may be specified by characters appended to the mode
argument of the fopen function (<a href="#7.21.5.3">7.21.5.3</a>).
<a name="J.5.16" href="#J.5.16"><h4>J.5.16 Defined file position indicator</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The file position indicator is decremented by each successful call to the ungetc or
ungetwc function for a text stream, except if its value was zero before a call (<a href="#7.21.7.10">7.21.7.10</a>,
<a href="#7.28.3.10">7.28.3.10</a>).
<a name="J.5.17" href="#J.5.17"><h4>J.5.17 Math error reporting</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Functions declared in <a href="#7.3"><complex.h></a> and <a href="#7.12"><math.h></a> raise SIGFPE to report errors
instead of, or in addition to, setting errno or raising floating-point exceptions (<a href="#7.3">7.3</a>,
<a href="#7.12">7.12</a>).
-<!--page 596 indent 4-->
+<!--page 596 -->
<a name="K" href="#K"><h2>Annex K</h2></a>
<pre>
Bounds-checking interfaces</pre>
<a name="K.1" href="#K.1"><h3>K.1 Background</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Traditionally, the C Library has contained many functions that trust the programmer to
provide output character arrays big enough to hold the result being produced. Not only
do these functions not check that the arrays are big enough, they frequently lack the
information needed to perform such checks. While it is possible to write safe, robust, and
error-free code using the existing library, the library tends to promote programming styles
that lead to mysterious failures if a result is too big for the provided array.
-<p><!--para 2-->
+<p><!--para 2 -->
A common programming style is to declare character arrays large enough to handle most
practical cases. However, if these arrays are not large enough to handle the resulting
strings, data can be written past the end of the array overwriting other data and program
structures. The program never gets any indication that a problem exists, and so never has
a chance to recover or to fail gracefully.
-<p><!--para 3-->
+<p><!--para 3 -->
Worse, this style of programming has compromised the security of computers and
networks. Buffer overflows can often be exploited to run arbitrary code with the
permissions of the vulnerable (defective) program.
-<p><!--para 4-->
+<p><!--para 4 -->
If the programmer writes runtime checks to verify lengths before calling library
functions, then those runtime checks frequently duplicate work done inside the library
functions, which discover string lengths as a side effect of doing their job.
-<p><!--para 5-->
+<p><!--para 5 -->
This annex provides alternative library functions that promote safer, more secure
programming. The alternative functions verify that output buffers are large enough for
the intended result and return a failure indicator if they are not. Data is never written past
the end of an array. All string results are null terminated.
-<p><!--para 6-->
+<p><!--para 6 -->
This annex also addresses another problem that complicates writing robust code:
functions that are not reentrant because they return pointers to static objects owned by the
function. Such functions can be troublesome since a previously returned result can
change if the function is called again, perhaps by another thread.
-<!--page 597 indent 4-->
+<!--page 597 -->
<a name="K.2" href="#K.2"><h3>K.2 Scope</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This annex specifies a series of optional extensions that can be useful in the mitigation of
security vulnerabilities in programs, and comprise new functions, macros, and types
declared or defined in existing standard headers.
-<p><!--para 2-->
+<p><!--para 2 -->
An implementation that defines __STDC_LIB_EXT1__ shall conform to the
specifications in this annex.<sup><a href="#note367"><b>367)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
Subclause <a href="#K.3">K.3</a> should be read as if it were merged into the parallel structure of named
subclauses of clause 7.
<a name="K.3.1" href="#K.3.1"><h4>K.3.1 Introduction</h4></a>
<a name="K.3.1.1" href="#K.3.1.1"><h5>K.3.1.1 Standard headers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The functions, macros, and types declared or defined in <a href="#K.3">K.3</a> and its subclauses are not
declared or defined by their respective headers if __STDC_WANT_LIB_EXT1__ is
defined as a macro which expands to the integer constant 0 at the point in the source file
where the appropriate header is first included.
-<p><!--para 2-->
+<p><!--para 2 -->
The functions, macros, and types declared or defined in <a href="#K.3">K.3</a> and its subclauses are
declared and defined by their respective headers if __STDC_WANT_LIB_EXT1__ is
defined as a macro which expands to the integer constant 1 at the point in the source file
where the appropriate header is first included.<sup><a href="#note368"><b>368)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
It is implementation-defined whether the functions, macros, and types declared or defined
in <a href="#K.3">K.3</a> and its subclauses are declared or defined by their respective headers if
__STDC_WANT_LIB_EXT1__ is not defined as a macro at the point in the source file
where the appropriate header is first included.<sup><a href="#note369"><b>369)</b></a></sup>
-<p><!--para 4-->
+<p><!--para 4 -->
Within a preprocessing translation unit, __STDC_WANT_LIB_EXT1__ shall be
defined identically for all inclusions of any headers from subclause <a href="#K.3">K.3</a>. If
__STDC_WANT_LIB_EXT1__ is defined differently for any such inclusion, the
implementation shall issue a diagnostic as if a preprocessor error directive were used.
-<!--page 598 indent 4-->
+<!--page 598 -->
<h6>footnotes</h6>
<p><small><a name="note368" href="#note368">368)</a> Future revisions of this International Standard may define meanings for other values of
</small>
<a name="K.3.1.2" href="#K.3.1.2"><h5>K.3.1.2 Reserved identifiers</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Each macro name in any of the following subclauses is reserved for use as specified if it
is defined by any of its associated headers when included; unless explicitly stated
otherwise (see <a href="#7.1.4">7.1.4</a>).
-<p><!--para 2-->
+<p><!--para 2 -->
All identifiers with external linkage in any of the following subclauses are reserved for
use as identifiers with external linkage if any of them are used by the program. None of
them are reserved if none of them are used.
-<p><!--para 3-->
+<p><!--para 3 -->
Each identifier with file scope listed in any of the following subclauses is reserved for use
as a macro name and as an identifier with file scope in the same name space if it is
defined by any of its associated headers when included.
<a name="K.3.1.3" href="#K.3.1.3"><h5>K.3.1.3 Use of errno</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
An implementation may set errno for the functions defined in this annex, but is not
required to.
<a name="K.3.1.4" href="#K.3.1.4"><h5>K.3.1.4 Runtime-constraint violations</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Most functions in this annex include as part of their specification a list of runtime-
constraints. These runtime-constraints are requirements on the program using the
library.<sup><a href="#note370"><b>370)</b></a></sup>
-<p><!--para 2-->
+<p><!--para 2 -->
Implementations shall verify that the runtime-constraints for a function are not violated
by the program. If a runtime-constraint is violated, the implementation shall call the
currently registered runtime-constraint handler (see set_constraint_handler_s
in <a href="#7.22"><stdlib.h></a>). Multiple runtime-constraint violations in the same call to a library
function result in only one call to the runtime-constraint handler. It is unspecified which
one of the multiple runtime-constraint violations cause the handler to be called.
-<p><!--para 3-->
+<p><!--para 3 -->
If the runtime-constraints section for a function states an action to be performed when a
runtime-constraint violation occurs, the function shall perform the action before calling
the runtime-constraint handler. If the runtime-constraints section lists actions that are
prohibited when a runtime-constraint violation occurs, then such actions are prohibited to
the function both before calling the handler and after the handler returns.
-<p><!--para 4-->
+<p><!--para 4 -->
The runtime-constraint handler might not return. If the handler does return, the library
function whose runtime-constraint was violated shall return some indication of failure as
given by the returns section in the function's specification.
-<!--page 599 indent 4-->
+<!--page 599 -->
<h6>footnotes</h6>
<p><small><a name="note370" href="#note370">370)</a> Although runtime-constraints replace many cases of undefined behavior, undefined behavior still
</small>
<a name="K.3.2" href="#K.3.2"><h4>K.3.2 Errors <errno.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.5"><errno.h></a> defines a type.
-<p><!--para 2-->
+<p><!--para 2 -->
The type is
<pre>
errno_t</pre>
</small>
<a name="K.3.3" href="#K.3.3"><h4>K.3.3 Common definitions <stddef.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.19"><stddef.h></a> defines a type.
-<p><!--para 2-->
+<p><!--para 2 -->
The type is
<pre>
rsize_t</pre>
</small>
<a name="K.3.4" href="#K.3.4"><h4>K.3.4 Integer types <stdint.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.20"><stdint.h></a> defines a macro.
-<p><!--para 2-->
+<p><!--para 2 -->
The macro is
<pre>
RSIZE_MAX</pre>
rsize_t consider it a runtime-constraint violation if the values of those parameters are
greater than RSIZE_MAX.
Recommended practice
-<p><!--para 3-->
+<p><!--para 3 -->
Extremely large object sizes are frequently a sign that an object's size was calculated
incorrectly. For example, negative numbers appear as very large positive numbers when
converted to an unsigned type like size_t. Also, some implementations do not support
objects as large as the maximum value that can be represented by type size_t.
-<p><!--para 4-->
+<p><!--para 4 -->
For those reasons, it is sometimes beneficial to restrict the range of object sizes to detect
programming errors. For implementations targeting machines with large address spaces,
it is recommended that RSIZE_MAX be defined as the smaller of the size of the largest
some legitimate, but very large, objects. Implementations targeting machines with small
address spaces may wish to define RSIZE_MAX as SIZE_MAX, which means that there
-<!--page 600 indent 4-->
+<!--page 600 -->
is no object size that is considered a runtime-constraint violation.
<h6>footnotes</h6>
</small>
<a name="K.3.5" href="#K.3.5"><h4>K.3.5 Input/output <stdio.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.21"><stdio.h></a> defines several macros and two types.
-<p><!--para 2-->
+<p><!--para 2 -->
The macros are
<pre>
L_tmpnam_s</pre>
TMP_MAX_S</pre>
which expands to an integer constant expression that is the maximum number of unique
file names that can be generated by the tmpnam_s function.
-<p><!--para 3-->
+<p><!--para 3 -->
The types are
<pre>
errno_t</pre>
<a name="K.3.5.1.1" href="#K.3.5.1.1"><h5>K.3.5.1.1 The tmpfile_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
errno_t tmpfile_s(FILE * restrict * restrict streamptr);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
streamptr shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, tmpfile_s does not attempt to create a file.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The tmpfile_s function creates a temporary binary file that is different from any other
existing file and that will automatically be removed when it is closed or at program
termination. If the program terminates abnormally, whether an open temporary file is
removed is implementation-defined. The file is opened for update with "wb+" mode
with the meaning that mode has in the fopen_s function (including the mode's effect
on exclusive access and file permissions).
-<!--page 601 indent 4-->
-<p><!--para 5-->
+<!--page 601 -->
+<p><!--para 5 -->
If the file was created successfully, then the pointer to FILE pointed to by streamptr
will be set to the pointer to the object controlling the opened file. Otherwise, the pointer
to FILE pointed to by streamptr will be set to a null pointer.
the number simultaneously open other than this limit and any limit on the number of open
files (FOPEN_MAX).
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The tmpfile_s function returns zero if it created the file. If it did not create the file or
there was a runtime-constraint violation, tmpfile_s returns a nonzero value.
<a name="K.3.5.1.2" href="#K.3.5.1.2"><h5>K.3.5.1.2 The tmpnam_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
errno_t tmpnam_s(char *s, rsize_t maxsize);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
s shall not be a null pointer. maxsize shall be less than or equal to RSIZE_MAX.
maxsize shall be greater than the length of the generated file name string.
<h6>Description</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The tmpnam_s function generates a string that is a valid file name and that is not the
same as the name of an existing file.<sup><a href="#note374"><b>374)</b></a></sup> The function is potentially capable of generating
TMP_MAX_S different strings, but any or all of them may already be in use by existing
files and thus not be suitable return values. The lengths of these strings shall be less than
the value of the L_tmpnam_s macro.
-<p><!--para 4-->
+<p><!--para 4 -->
The tmpnam_s function generates a different string each time it is called.
-<p><!--para 5-->
+<p><!--para 5 -->
It is assumed that s points to an array of at least maxsize characters. This array will be
set to generated string, as specified below.
-<!--page 602 indent 5-->
-<p><!--para 6-->
+<!--page 602 -->
+<p><!--para 6 -->
The implementation shall behave as if no library function except tmpnam calls the
tmpnam_s function.<sup><a href="#note375"><b>375)</b></a></sup>
Recommended practice
-<p><!--para 7-->
+<p><!--para 7 -->
After a program obtains a file name using the tmpnam_s function and before the
program creates a file with that name, the possibility exists that someone else may create
a file with that same name. To avoid this race condition, the tmpfile_s function
of the tmpnam_s function is when the program needs to create a temporary directory
rather than a temporary file.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
If no suitable string can be generated, or if there is a runtime-constraint violation, the
tmpnam_s function writes a null character to s[0] (only if s is not null and maxsize
is greater than zero) and returns a nonzero value.
-<p><!--para 9-->
+<p><!--para 9 -->
Otherwise, the tmpnam_s function writes the string in the array pointed to by s and
returns zero.
Environmental limits
-<p><!--para 10-->
+<p><!--para 10 -->
The value of the macro TMP_MAX_S shall be at least 25.
<h6>footnotes</h6>
<a name="K.3.5.2.1" href="#K.3.5.2.1"><h5>K.3.5.2.1 The fopen_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
const char * restrict filename,
const char * restrict mode);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
None of streamptr, filename, or mode shall be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, fopen_s does not attempt to open a file.
Furthermore, if streamptr is not a null pointer, fopen_s sets *streamptr to the
null pointer.
-<!--page 603 indent 4-->
+<!--page 603 -->
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The fopen_s function opens the file whose name is the string pointed to by
filename, and associates a stream with it.
-<p><!--para 5-->
+<p><!--para 5 -->
The mode string shall be as described for fopen, with the addition that modes starting
with the character 'w' or 'a' may be preceded by the character 'u', see below:
uw truncate to zero length or create text file for writing, default
permissions</pre>
uw+bx or uwb+x create binary file for update, default permissions
ua+b or uab+ append; open or create binary file for update, writing at end-of-file,
-<p><!--para 6-->
+<p><!--para 6 -->
<pre>
default permissions</pre>
Opening a file with exclusive mode ('x' as the last character in the mode argument)
fails if the file already exists or cannot be created.
-<p><!--para 7-->
+<p><!--para 7 -->
To the extent that the underlying system supports the concepts, files opened for writing
shall be opened with exclusive (also known as non-shared) access. If the file is being
created, and the first character of the mode string is not 'u', to the extent that the
users on the system from accessing the file. If the file is being created and first character
of the mode string is 'u', then by the time the file has been closed, it shall have the
system default file access permissions.<sup><a href="#note376"><b>376)</b></a></sup>
-<p><!--para 8-->
+<p><!--para 8 -->
If the file was opened successfully, then the pointer to FILE pointed to by streamptr
will be set to the pointer to the object controlling the opened file. Otherwise, the pointer
-<!--page 604 indent 4-->
+<!--page 604 -->
to FILE pointed to by streamptr will be set to a null pointer.
<h6>Returns</h6>
-<p><!--para 9-->
+<p><!--para 9 -->
The fopen_s function returns zero if it opened the file. If it did not open the file or if
there was a runtime-constraint violation, fopen_s returns a nonzero value.
<a name="K.3.5.2.2" href="#K.3.5.2.2"><h5>K.3.5.2.2 The freopen_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
const char * restrict mode,
FILE * restrict stream);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
None of newstreamptr, mode, and stream shall be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, freopen_s neither attempts to close any file
associated with stream nor attempts to open a file. Furthermore, if newstreamptr is
not a null pointer, fopen_s sets *newstreamptr to the null pointer.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The freopen_s function opens the file whose name is the string pointed to by
filename and associates the stream pointed to by stream with it. The mode
argument has the same meaning as in the fopen_s function (including the mode's effect
on exclusive access and file permissions).
-<p><!--para 5-->
+<p><!--para 5 -->
If filename is a null pointer, the freopen_s 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
permitted (if any), and under what circumstances.
-<p><!--para 6-->
+<p><!--para 6 -->
The freopen_s function first attempts to close any file that is associated with stream.
Failure to close the file is ignored. The error and end-of-file indicators for the stream are
cleared.
-<p><!--para 7-->
+<p><!--para 7 -->
If the file was opened successfully, then the pointer to FILE pointed to by
newstreamptr will be set to the value of stream. Otherwise, the pointer to FILE
pointed to by newstreamptr will be set to a null pointer.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The freopen_s function returns zero if it opened the file. If it did not open the file or
there was a runtime-constraint violation, freopen_s returns a nonzero value.
-<!--page 605 indent 4-->
+<!--page 605 -->
<a name="K.3.5.3" href="#K.3.5.3"><h5>K.3.5.3 Formatted input/output functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Unless explicitly stated otherwise, if the execution of a function described in this
subclause causes copying to take place between objects that overlap, the objects take on
unspecified values.
<a name="K.3.5.3.1" href="#K.3.5.3.1"><h5>K.3.5.3.1 The fprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
int fprintf_s(FILE * restrict stream,
const char * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither stream nor format shall be a null pointer. The %n specifier<sup><a href="#note377"><b>377)</b></a></sup> (modified or
not by flags, field width, or precision) shall not appear in the string pointed to by
format. Any argument to fprintf_s corresponding to a %s specifier shall not be a
null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation,<sup><a href="#note378"><b>378)</b></a></sup> the fprintf_s function does not attempt
to produce further output, and it is unspecified to what extent fprintf_s produced
output before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The fprintf_s function is equivalent to the fprintf function except for the explicit
runtime-constraints listed above.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The fprintf_s function returns the number of characters transmitted, or a negative
value if an output error, encoding error, or runtime-constraint violation occurred.
-<!--page 606 indent 4-->
+<!--page 606 -->
<h6>footnotes</h6>
<p><small><a name="note377" href="#note377">377)</a> It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
<a name="K.3.5.3.2" href="#K.3.5.3.2"><h5>K.3.5.3.2 The fscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
int fscanf_s(FILE * restrict stream,
const char * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither stream nor format shall be a null pointer. Any argument indirected though in
order to store converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation,<sup><a href="#note379"><b>379)</b></a></sup> the fscanf_s function does not attempt to
perform further input, and it is unspecified to what extent fscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The fscanf_s function is equivalent to fscanf except that the c, s, and [ conversion
specifiers apply to a pair of arguments (unless assignment suppression is indicated by a
*). The first of these arguments is the same as for fscanf. That argument is
rsize_t and gives the number of elements in the array pointed to by the first argument
of the pair. If the first argument points to a scalar object, it is considered to be an array of
one element.<sup><a href="#note380"><b>380)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
A matching failure occurs if the number of elements in a receiving object is insufficient to
hold the converted input (including any trailing null character).
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The fscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
-<!--page 607 indent 4-->
+<!--page 607 -->
fscanf_s function returns the number of input items assigned, which can be fewer than
provided for, or even zero, in the event of an early matching failure.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1 The call:
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
will assign to n the value 3, to i the value 25, to x the value 5.432, and to name the sequence
thompson\0.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 2 The call:
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
<a name="K.3.5.3.3" href="#K.3.5.3.3"><h5>K.3.5.3.3 The printf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
int printf_s(const char * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
format shall not be a null pointer. The %n specifier<sup><a href="#note381"><b>381)</b></a></sup> (modified or not by flags, field
width, or precision) shall not appear in the string pointed to by format. Any argument
to printf_s corresponding to a %s specifier shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the printf_s function does not attempt to
produce further output, and it is unspecified to what extent printf_s produced output
before discovering the runtime-constraint violation.
-<!--page 608 indent 4-->
+<!--page 608 -->
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The printf_s function is equivalent to the printf function except for the explicit
runtime-constraints listed above.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The printf_s function returns the number of characters transmitted, or a negative
value if an output error, encoding error, or runtime-constraint violation occurred.
<a name="K.3.5.3.4" href="#K.3.5.3.4"><h5>K.3.5.3.4 The scanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
int scanf_s(const char * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
format shall not be a null pointer. Any argument indirected though in order to store
converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the scanf_s function does not attempt to
perform further input, and it is unspecified to what extent scanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The scanf_s function is equivalent to fscanf_s with the argument stdin
interposed before the arguments to scanf_s.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The scanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
scanf_s function returns the number of input items assigned, which can be fewer than
<a name="K.3.5.3.5" href="#K.3.5.3.5"><h5>K.3.5.3.5 The snprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
int snprintf_s(char * restrict s, rsize_t n,
const char * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
than RSIZE_MAX. The %n specifier<sup><a href="#note382"><b>382)</b></a></sup> (modified or not by flags, field width, or
precision) shall not appear in the string pointed to by format. Any argument to
-<!--page 609 indent 4-->
+<!--page 609 -->
snprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding
error shall occur.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
than zero and less than RSIZE_MAX, then the snprintf_s function sets s[0] to the
null character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The snprintf_s function is equivalent to the snprintf function except for the
explicit runtime-constraints listed above.
-<p><!--para 5-->
+<p><!--para 5 -->
The snprintf_s function, unlike sprintf_s, will truncate the result to fit within the
array pointed to by s.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The snprintf_s function returns the number of characters that would have been
written had n been sufficiently large, not counting the terminating null character, or a
negative value if a runtime-constraint violation occurred. Thus, the null-terminated
<a name="K.3.5.3.6" href="#K.3.5.3.6"><h5>K.3.5.3.6 The sprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
int sprintf_s(char * restrict s, rsize_t n,
const char * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
than RSIZE_MAX. The number of characters (including the trailing null) required for the
result to be written to the array pointed to by s shall not be greater than n. The %n
-<!--page 610 indent 4-->
-<p><!--para 3-->
+<!--page 610 -->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
than zero and less than RSIZE_MAX, then the sprintf_s function sets s[0] to the
null character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The sprintf_s function is equivalent to the sprintf function except for the
parameter n and the explicit runtime-constraints listed above.
-<p><!--para 5-->
+<p><!--para 5 -->
The sprintf_s function, unlike snprintf_s, treats a result too big for the array
pointed to by s as a runtime-constraint violation.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
If no runtime-constraint violation occurred, the sprintf_s function returns the number
of characters written in the array, not counting the terminating null character. If an
encoding error occurred, sprintf_s returns a negative value. If any other runtime-
<a name="K.3.5.3.7" href="#K.3.5.3.7"><h5>K.3.5.3.7 The sscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
int sscanf_s(const char * restrict s,
const char * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. Any argument indirected though in order
to store converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the sscanf_s function does not attempt to
perform further input, and it is unspecified to what extent sscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The sscanf_s function is equivalent to fscanf_s, except that input is obtained from
a string (specified by the argument s) rather than from a stream. Reaching the end of the
string is equivalent to encountering end-of-file for the fscanf_s function. If copying
takes place between objects that overlap, the objects take on unspecified values.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The sscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
sscanf_s function returns the number of input items assigned, which can be fewer than
provided for, or even zero, in the event of an early matching failure.
-<!--page 611 indent 4-->
+<!--page 611 -->
<a name="K.3.5.3.8" href="#K.3.5.3.8"><h5>K.3.5.3.8 The vfprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
const char * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither stream nor format shall be a null pointer. The %n specifier<sup><a href="#note384"><b>384)</b></a></sup> (modified or
not by flags, field width, or precision) shall not appear in the string pointed to by
format. Any argument to vfprintf_s corresponding to a %s specifier shall not be a
null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vfprintf_s function does not attempt to
produce further output, and it is unspecified to what extent vfprintf_s produced
output before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vfprintf_s function is equivalent to the vfprintf function except for the
explicit runtime-constraints listed above.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vfprintf_s function returns the number of characters transmitted, or a negative
value if an output error, encoding error, or runtime-constraint violation occurred.
<a name="K.3.5.3.9" href="#K.3.5.3.9"><h5>K.3.5.3.9 The vfscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
-<!--page 612 indent 4-->
+<!--page 612 -->
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither stream nor format shall be a null pointer. Any argument indirected though in
order to store converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vfscanf_s function does not attempt to
perform further input, and it is unspecified to what extent vfscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vfscanf_s function is equivalent to fscanf_s, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfscanf_s function does not invoke the
va_end macro.<sup><a href="#note385"><b>385)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vfscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
vfscanf_s function returns the number of input items assigned, which can be fewer
<a name="K.3.5.3.10" href="#K.3.5.3.10"><h5>K.3.5.3.10 The vprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
int vprintf_s(const char * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
format shall not be a null pointer. The %n specifier<sup><a href="#note386"><b>386)</b></a></sup> (modified or not by flags, field
width, or precision) shall not appear in the string pointed to by format. Any argument
to vprintf_s corresponding to a %s specifier shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vprintf_s function does not attempt to
produce further output, and it is unspecified to what extent vprintf_s produced output
before discovering the runtime-constraint violation.
-<!--page 613 indent 4-->
+<!--page 613 -->
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vprintf_s function is equivalent to the vprintf function except for the explicit
runtime-constraints listed above.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vprintf_s function returns the number of characters transmitted, or a negative
value if an output error, encoding error, or runtime-constraint violation occurred.
<a name="K.3.5.3.11" href="#K.3.5.3.11"><h5>K.3.5.3.11 The vscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
int vscanf_s(const char * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
format shall not be a null pointer. Any argument indirected though in order to store
converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vscanf_s function does not attempt to
perform further input, and it is unspecified to what extent vscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vscanf_s function is equivalent to scanf_s, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vscanf_s function does not invoke the
va_end macro.<sup><a href="#note387"><b>387)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
vscanf_s function returns the number of input items assigned, which can be fewer than
-<!--page 614 indent 4-->
+<!--page 614 -->
<h6>footnotes</h6>
<p><small><a name="note387" href="#note387">387)</a> As the functions vfprintf_s, vfscanf_s, vprintf_s, vscanf_s, vsnprintf_s,
<a name="K.3.5.3.12" href="#K.3.5.3.12"><h5>K.3.5.3.12 The vsnprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
const char * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
than RSIZE_MAX. The %n specifier<sup><a href="#note388"><b>388)</b></a></sup> (modified or not by flags, field width, or
precision) shall not appear in the string pointed to by format. Any argument to
vsnprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding
error shall occur.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
than zero and less than RSIZE_MAX, then the vsnprintf_s function sets s[0] to the
null character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vsnprintf_s function is equivalent to the vsnprintf function except for the
explicit runtime-constraints listed above.
-<p><!--para 5-->
+<p><!--para 5 -->
The vsnprintf_s function, unlike vsprintf_s, will truncate the result to fit within
the array pointed to by s.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The vsnprintf_s function returns the number of characters that would have been
written had n been sufficiently large, not counting the terminating null character, or a
negative value if a runtime-constraint violation occurred. Thus, the null-terminated
-<!--page 615 indent 4-->
+<!--page 615 -->
<h6>footnotes</h6>
<p><small><a name="note388" href="#note388">388)</a> It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
<a name="K.3.5.3.13" href="#K.3.5.3.13"><h5>K.3.5.3.13 The vsprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
const char * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
than RSIZE_MAX. The number of characters (including the trailing null) required for the
result to be written to the array pointed to by s shall not be greater than n. The %n
specifier<sup><a href="#note389"><b>389)</b></a></sup> (modified or not by flags, field width, or precision) shall not appear in the
string pointed to by format. Any argument to vsprintf_s corresponding to a %s
specifier shall not be a null pointer. No encoding error shall occur.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
than zero and less than RSIZE_MAX, then the vsprintf_s function sets s[0] to the
null character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vsprintf_s function is equivalent to the vsprintf function except for the
parameter n and the explicit runtime-constraints listed above.
-<p><!--para 5-->
+<p><!--para 5 -->
The vsprintf_s function, unlike vsnprintf_s, treats a result too big for the array
pointed to by s as a runtime-constraint violation.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
If no runtime-constraint violation occurred, the vsprintf_s function returns the
number of characters written in the array, not counting the terminating null character. If
an encoding error occurred, vsprintf_s returns a negative value. If any other
-<!--page 616 indent 4-->
+<!--page 616 -->
<h6>footnotes</h6>
<p><small><a name="note389" href="#note389">389)</a> It is not a runtime-constraint violation for the characters %n to appear in sequence in the string pointed
<a name="K.3.5.3.14" href="#K.3.5.3.14"><h5>K.3.5.3.14 The vsscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
const char * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. Any argument indirected though in order
to store converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vsscanf_s function does not attempt to
perform further input, and it is unspecified to what extent vsscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vsscanf_s function is equivalent to sscanf_s, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vsscanf_s function does not invoke the
va_end macro.<sup><a href="#note390"><b>390)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vsscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
vscanf_s function returns the number of input items assigned, which can be fewer than
<a name="K.3.5.4.1" href="#K.3.5.4.1"><h5>K.3.5.4.1 The gets_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
-<!--page 617 indent 4-->
+<!--page 617 -->
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
s shall not be a null pointer. n shall neither be equal to zero nor be greater than
RSIZE_MAX. A new-line character, end-of-file, or read error shall occur within reading
n-1 characters from stdin.<sup><a href="#note391"><b>391)</b></a></sup>
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, s[0] is set to the null character, and characters
are read and discarded from stdin until a new-line character is read, or end-of-file or a
read error occurs.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The gets_s function reads at most one less than the number of characters specified by n
from the stream pointed to by stdin, into the array pointed to by s. No additional
characters are read after a new-line character (which is discarded) or after end-of-file.
The discarded new-line character does not count towards number of characters read. A
null character is written immediately after the last character read into the array.
-<p><!--para 5-->
+<p><!--para 5 -->
If end-of-file is encountered and no characters have been read into the array, or if a read
error occurs during the operation, then s[0] is set to the null character, and the other
elements of s take unspecified values.
Recommended practice
-<p><!--para 6-->
+<p><!--para 6 -->
The fgets function allows properly-written programs to safely process input lines too
long to store in the result array. In general this requires that callers of fgets pay
attention to the presence or absence of a new-line character in the result array. Consider
using fgets (along with any needed processing based on new-line characters) instead of
gets_s.
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The gets_s function returns s if successful. If there was a runtime-constraint violation,
or if end-of-file is encountered and no characters have been read into the array, or if a
read error occurs during the operation, then a null pointer is returned.
-<!--page 618 indent 4-->
+<!--page 618 -->
<h6>footnotes</h6>
<p><small><a name="note391" href="#note391">391)</a> The gets_s function, unlike the historical gets function, makes it a runtime-constraint violation for
</small>
<a name="K.3.6" href="#K.3.6"><h4>K.3.6 General utilities <stdlib.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.22"><stdlib.h></a> defines three types.
-<p><!--para 2-->
+<p><!--para 2 -->
The types are
<pre>
errno_t</pre>
<a name="K.3.6.1.1" href="#K.3.6.1.1"><h5>K.3.6.1.1 The set_constraint_handler_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.22"><stdlib.h></a>
constraint_handler_t set_constraint_handler_s(
constraint_handler_t handler);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The set_constraint_handler_s function sets the runtime-constraint handler to
be handler. The runtime-constraint handler is the function to be called when a library
function detects a runtime-constraint violation. Only the most recent handler registered
with set_constraint_handler_s is called when a runtime-constraint violation
occurs.
-<p><!--para 3-->
+<p><!--para 3 -->
When the handler is called, it is passed the following arguments in the following order:
<ol>
<li> A pointer to a character string describing the runtime-constraint violation.
<li> If the function calling the handler has a return type declared as errno_t, the
return value of the function is passed. Otherwise, a positive value of type
errno_t is passed.
-<!--page 619 indent 4-->
+<!--page 619 -->
</ol>
-<p><!--para 4-->
+<p><!--para 4 -->
The implementation has a default constraint handler that is used if no calls to the
set_constraint_handler_s function have been made. The behavior of the
default handler is implementation-defined, and it may cause the program to exit or abort.
-<p><!--para 5-->
+<p><!--para 5 -->
If the handler argument to set_constraint_handler_s is a null pointer, the
implementation default handler becomes the current constraint handler.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The set_constraint_handler_s function returns a pointer to the previously
registered handler.<sup><a href="#note392"><b>392)</b></a></sup>
<a name="K.3.6.1.2" href="#K.3.6.1.2"><h5>K.3.6.1.2 The abort_handler_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.22"><stdlib.h></a>
void * restrict ptr,
errno_t error);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A pointer to the abort_handler_s function shall be a suitable argument to the
set_constraint_handler_s function.
-<p><!--para 3-->
+<p><!--para 3 -->
The abort_handler_s function writes a message on the standard error stream in an
implementation-defined format. The message shall include the string pointed to by msg.
The abort_handler_s function then calls the abort function.<sup><a href="#note393"><b>393)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The abort_handler_s function does not return to its caller.
-<!--page 620 indent 4-->
+<!--page 620 -->
<h6>footnotes</h6>
<p><small><a name="note393" href="#note393">393)</a> Many implementations invoke a debugger when the abort function is called.
<a name="K.3.6.1.3" href="#K.3.6.1.3"><h5>K.3.6.1.3 The ignore_handler_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.22"><stdlib.h></a>
void * restrict ptr,
errno_t error);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
A pointer to the ignore_handler_s function shall be a suitable argument to the
set_constraint_handler_s function.
-<p><!--para 3-->
+<p><!--para 3 -->
The ignore_handler_s function simply returns to its caller.<sup><a href="#note394"><b>394)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The ignore_handler_s function returns no value.
<h6>footnotes</h6>
<a name="K.3.6.2.1" href="#K.3.6.2.1"><h5>K.3.6.2.1 The getenv_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.22"><stdlib.h></a>
char * restrict value, rsize_t maxsize,
const char * restrict name);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
name shall not be a null pointer. maxsize shall neither equal zero nor be greater than
RSIZE_MAX. If maxsize is not equal to zero, then value shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the integer pointed to by len is set to 0 (if len
is not null), and the environment list is not searched.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The getenv_s function searches an environment list, provided by the host environment,
for a string that matches the string pointed to by name.
-<!--page 621 indent 4-->
-<p><!--para 5-->
+<!--page 621 -->
+<p><!--para 5 -->
If that name is found then getenv_s performs the following actions. If len is not a
null pointer, the length of the string associated with the matched list member is stored in
the integer pointed to by len. If the length of the associated string is less than maxsize,
then the associated string is copied to the array pointed to by value.
-<p><!--para 6-->
+<p><!--para 6 -->
If that name is not found then getenv_s performs the following actions. If len is not
a null pointer, zero is stored in the integer pointed to by len. If maxsize is greater than
zero, then value[0] is set to the null character.
-<p><!--para 7-->
+<p><!--para 7 -->
The set of environment names and the method for altering the environment list are
implementation-defined.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The getenv_s function returns zero if the specified name is found and the associated
string was successfully stored in value. Otherwise, a nonzero value is returned.
<a name="K.3.6.3" href="#K.3.6.3"><h5>K.3.6.3 Searching and sorting utilities</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
These utilities make use of a comparison function to search or sort arrays of unspecified
type. Where an argument declared as size_t nmemb specifies the length of the array
for a function, if nmemb has the value zero on a call to that function, then the comparison
function is not called, a search finds no matching element, sorting performs no
rearrangement, and the pointer to the array may be null.
-<p><!--para 2-->
+<p><!--para 2 -->
The implementation shall ensure that the second argument of the comparison function
(when called from bsearch_s), or both arguments (when called from qsort_s), are
pointers to elements of the array.<sup><a href="#note395"><b>395)</b></a></sup> The first argument when called from bsearch_s
shall equal key.
-<p><!--para 3-->
+<p><!--para 3 -->
The comparison function shall not alter the contents of either the array or search key. The
implementation may reorder elements of the array between calls to the comparison
function, but shall not otherwise alter the contents of any individual element.
-<p><!--para 4-->
+<p><!--para 4 -->
When the same objects (consisting of size bytes, irrespective of their current positions
in the array) are passed more than once to the comparison function, the results shall be
consistent with one another. That is, for qsort_s they shall define a total ordering on
-<!--page 622 indent 4-->
-<p><!--para 5-->
+<!--page 622 -->
+<p><!--para 5 -->
A sequence point occurs immediately before and immediately after each call to the
comparison function, and also between any call to the comparison function and any
movement of the objects passed as arguments to that call.
<a name="K.3.6.3.1" href="#K.3.6.3.1"><h5>K.3.6.3.1 The bsearch_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.22"><stdlib.h></a>
void *context),
void *context);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither nmemb nor size shall be greater than RSIZE_MAX. If nmemb is not equal to
zero, then none of key, base, or compar shall be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the bsearch_s function does not search the
array.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The bsearch_s function searches an array of nmemb objects, the initial element of
which is pointed to by base, for an element that matches the object pointed to by key.
The size of each element of the array is specified by size.
-<p><!--para 5-->
+<p><!--para 5 -->
The comparison function pointed to by compar is called with three arguments. The first
two point to the key object and to an array element, in that order. The function shall
return an integer less than, equal to, or greater than zero if the key object is considered,
-<!--page 623 indent 4-->
+<!--page 623 -->
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The bsearch_s function returns a pointer to a matching element of the array, or a null
pointer if no match is found or there is a runtime-constraint violation. If two elements
compare as equal, which element is matched is unspecified.
<a name="K.3.6.3.2" href="#K.3.6.3.2"><h5>K.3.6.3.2 The qsort_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.22"><stdlib.h></a>
void *context),
void *context);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither nmemb nor size shall be greater than RSIZE_MAX. If nmemb is not equal to
zero, then neither base nor compar shall be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the qsort_s function does not sort the array.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The qsort_s function sorts an array of nmemb objects, the initial element of which is
pointed to by base. The size of each object is specified by size.
-<p><!--para 5-->
+<p><!--para 5 -->
The contents of the array are sorted into ascending order according to a comparison
function pointed to by compar, which is called with three arguments. The first two
point to the objects being compared. The function shall return an integer less than, equal
equal to, or greater than the second. The third argument to the comparison function is the
context argument passed to qsort_s. The sole use of context by qsort_s is to
pass it to the comparison function.<sup><a href="#note398"><b>398)</b></a></sup>
-<p><!--para 6-->
+<p><!--para 6 -->
If two elements compare as equal, their relative order in the resulting sorted array is
unspecified.
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The qsort_s function returns zero if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
-<!--page 624 indent 4-->
+<!--page 624 -->
<h6>footnotes</h6>
<p><small><a name="note398" href="#note398">398)</a> The context argument is for the use of the comparison function in performing its duties. For
</small>
<a name="K.3.6.4" href="#K.3.6.4"><h5>K.3.6.4 Multibyte/wide character conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior of the multibyte character functions is affected by the LC_CTYPE category
of the current locale. For a state-dependent encoding, each function is placed into its
initial conversion state by a call for which its character pointer argument, s, is a null
<a name="K.3.6.4.1" href="#K.3.6.4.1"><h5>K.3.6.4.1 The wctomb_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.22"><stdlib.h></a>
rsize_t smax,
wchar_t wc);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Let n denote the number of bytes needed to represent the multibyte character
corresponding to the wide character given by wc (including any shift sequences).
-<p><!--para 3-->
+<p><!--para 3 -->
If s is not a null pointer, then smax shall not be less than n, and smax shall not be
greater than RSIZE_MAX. If s is a null pointer, then smax shall equal zero.
-<p><!--para 4-->
+<p><!--para 4 -->
If there is a runtime-constraint violation, wctomb_s does not modify the int pointed to
by status, and if s is not a null pointer, no more than smax elements in the array
pointed to by s will be accessed.
<h6>Description</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The wctomb_s function determines n and stores the multibyte character representation
of wc in the array whose first element is pointed to by s (if s is not a null pointer). The
number of characters stored never exceeds MB_CUR_MAX or smax. If wc is a null wide
character, a null byte is stored, preceded by any shift sequence needed to restore the
initial shift state, and the function is left in the initial conversion state.
-<p><!--para 6-->
+<p><!--para 6 -->
The implementation shall behave as if no library function calls the wctomb_s function.
-<!--page 625 indent 5-->
-<p><!--para 7-->
+<!--page 625 -->
+<p><!--para 7 -->
If s is a null pointer, the wctomb_s function stores into the int pointed to by status a
nonzero or zero value, if multibyte character encodings, respectively, do or do not have
state-dependent encodings.
-<p><!--para 8-->
+<p><!--para 8 -->
If s is not a null pointer, the wctomb_s function stores into the int pointed to by
status either n or -1 if wc, respectively, does or does not correspond to a valid
multibyte character.
-<p><!--para 9-->
+<p><!--para 9 -->
In no case will the int pointed to by status be set to a value greater than the
MB_CUR_MAX macro.
<h6>Returns</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
The wctomb_s function returns zero if successful, and a nonzero value if there was a
runtime-constraint violation or wc did not correspond to a valid multibyte character.
<a name="K.3.6.5" href="#K.3.6.5"><h5>K.3.6.5 Multibyte/wide string conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The behavior of the multibyte string functions is affected by the LC_CTYPE category of
the current locale.
<a name="K.3.6.5.1" href="#K.3.6.5.1"><h5>K.3.6.5.1 The mbstowcs_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
errno_t mbstowcs_s(size_t * restrict retval,
wchar_t * restrict dst, rsize_t dstmax,
const char * restrict src, rsize_t len);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither retval nor src shall be a null pointer. If dst is not a null pointer, then
neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null pointer,
then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall not equal
zero. If dst is not a null pointer and len is not less than dstmax, then a null character
shall occur within the first dstmax multibyte characters of the array pointed to by src.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then mbstowcs_s does the following. If
retval is not a null pointer, then mbstowcs_s sets *retval to (size_t)(-1). If
dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX,
then mbstowcs_s sets dst[0] to the null wide character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The mbstowcs_s function converts a sequence of multibyte characters that begins in
the initial shift state from the array pointed to by src into a sequence of corresponding
wide characters. If dst is not a null pointer, the converted characters are stored into the
array pointed to by dst. Conversion continues up to and including a terminating null
character, which is also stored. Conversion stops earlier in two cases: when a sequence of
-<!--page 626 indent 4-->
+<!--page 626 -->
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.<sup><a href="#note400"><b>400)</b></a></sup> If dst is not a null pointer and no null wide character was stored into the array
pointed to by dst, then dst[len] is set to the null wide character. Each conversion
takes place as if by a call to the mbrtowc function.
-<p><!--para 5-->
+<p><!--para 5 -->
Regardless of whether dst is or is not a null pointer, if the input conversion encounters a
sequence of bytes that do not form a valid multibyte character, an encoding error occurs:
the mbstowcs_s function stores the value (size_t)(-1) into *retval.
Otherwise, the mbstowcs_s function stores into *retval the number of multibyte
characters successfully converted, not including the terminating null character (if any).
-<p><!--para 6-->
+<p><!--para 6 -->
All elements following the terminating null wide character (if any) written by
mbstowcs_s in the array of dstmax wide characters pointed to by dst take
unspecified values when mbstowcs_s returns.<sup><a href="#note401"><b>401)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 7 -->
If copying takes place between objects that overlap, the objects take on unspecified
values.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The mbstowcs_s function returns zero if no runtime-constraint violation and no
encoding error occurred. Otherwise, a nonzero value is returned.
<a name="K.3.6.5.2" href="#K.3.6.5.2"><h5>K.3.6.5.2 The wcstombs_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#include <a href="#7.22"><stdlib.h></a>
errno_t wcstombs_s(size_t * restrict retval,
char * restrict dst, rsize_t dstmax,
const wchar_t * restrict src, rsize_t len);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither retval nor src shall be a null pointer. If dst is not a null pointer, then
neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null pointer,
then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall not equal
-<!--page 627 indent 4-->
-<p><!--para 3-->
+<!--page 627 -->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then wcstombs_s does the following. If
retval is not a null pointer, then wcstombs_s sets *retval to (size_t)(-1). If
dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX,
then wcstombs_s sets dst[0] to the null character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The wcstombs_s function converts a sequence of wide characters from the array
pointed to by src into a sequence of corresponding multibyte characters that begins in
the initial shift state. If dst is not a null pointer, the converted characters are then stored
pointer, then a null character is stored into the array pointed to by dst immediately
following any multibyte characters already stored. Each conversion takes place as if by a
call to the wcrtomb function.<sup><a href="#note402"><b>402)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
Regardless of whether dst is or is not a null pointer, if the input conversion encounters a
wide character that does not correspond to a valid multibyte character, an encoding error
occurs: the wcstombs_s function stores the value (size_t)(-1) into *retval.
Otherwise, the wcstombs_s function stores into *retval the number of bytes in the
resulting multibyte character sequence, not including the terminating null character (if
any).
-<p><!--para 6-->
+<p><!--para 6 -->
All elements following the terminating null character (if any) written by wcstombs_s
in the array of dstmax elements pointed to by dst take unspecified values when
wcstombs_s returns.<sup><a href="#note403"><b>403)</b></a></sup>
-<p><!--para 7-->
+<p><!--para 7 -->
If copying takes place between objects that overlap, the objects take on unspecified
values.
-<!--page 628 indent 4-->
+<!--page 628 -->
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The wcstombs_s function returns zero if no runtime-constraint violation and no
encoding error occurred. Otherwise, a nonzero value is returned.
</small>
<a name="K.3.7" href="#K.3.7"><h4>K.3.7 String handling <string.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.23"><string.h></a> defines two types.
-<p><!--para 2-->
+<p><!--para 2 -->
The types are
<pre>
errno_t</pre>
<a name="K.3.7.1.1" href="#K.3.7.1.1"><h5>K.3.7.1.1 The memcpy_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
errno_t memcpy_s(void * restrict s1, rsize_t s1max,
const void * restrict s2, rsize_t n);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
RSIZE_MAX. n shall not be greater than s1max. Copying shall not take place between
objects that overlap.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the memcpy_s function stores zeros in the first
s1max characters of the object pointed to by s1 if s1 is not a null pointer and s1max is
not greater than RSIZE_MAX.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The memcpy_s function copies n characters from the object pointed to by s2 into the
object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The memcpy_s function returns zero if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
-<!--page 629 indent 4-->
+<!--page 629 -->
<a name="K.3.7.1.2" href="#K.3.7.1.2"><h5>K.3.7.1.2 The memmove_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
errno_t memmove_s(void *s1, rsize_t s1max,
const void *s2, rsize_t n);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
RSIZE_MAX. n shall not be greater than s1max.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the memmove_s function stores zeros in the
first s1max characters of the object pointed to by s1 if s1 is not a null pointer and
s1max is not greater than RSIZE_MAX.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The memmove_s function copies n characters from the object pointed to by s2 into the
object pointed to by s1. This copying takes place as if the n characters from the object
pointed to by s2 are first copied into a temporary array of n characters that does not
overlap the objects pointed to by s1 or s2, and then the n characters from the temporary
array are copied into the object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The memmove_s function returns zero if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
<a name="K.3.7.1.3" href="#K.3.7.1.3"><h5>K.3.7.1.3 The strcpy_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
rsize_t s1max,
const char * restrict s2);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX.
s1max shall not equal zero. s1max shall be greater than strnlen_s(s2, s1max).
Copying shall not take place between objects that overlap.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
greater than zero and not greater than RSIZE_MAX, then strcpy_s sets s1[0] to the
null character.
-<!--page 630 indent 4-->
+<!--page 630 -->
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The strcpy_s function copies the string pointed to by s2 (including the terminating
null character) into the array pointed to by s1.
-<p><!--para 5-->
+<p><!--para 5 -->
All elements following the terminating null character (if any) written by strcpy_s in
the array of s1max characters pointed to by s1 take unspecified values when
strcpy_s returns.<sup><a href="#note404"><b>404)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The strcpy_s function returns zero<sup><a href="#note405"><b>405)</b></a></sup> if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
<a name="K.3.7.1.4" href="#K.3.7.1.4"><h5>K.3.7.1.4 The strncpy_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
const char * restrict s2,
rsize_t n);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
RSIZE_MAX. s1max shall not equal zero. If n is not less than s1max, then s1max
shall be greater than strnlen_s(s2, s1max). Copying shall not take place between
objects that overlap.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
greater than zero and not greater than RSIZE_MAX, then strncpy_s sets s1[0] to the
null character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The strncpy_s function copies not more than n successive characters (characters that
follow a null character are not copied) from the array pointed to by s2 to the array
pointed to by s1. If no null character was copied from s2, then s1[n] is set to a null
character.
-<!--page 631 indent 4-->
-<p><!--para 5-->
+<!--page 631 -->
+<p><!--para 5 -->
All elements following the terminating null character (if any) written by strncpy_s in
the array of s1max characters pointed to by s1 take unspecified values when
strncpy_s returns.<sup><a href="#note406"><b>406)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The strncpy_s function returns zero<sup><a href="#note407"><b>407)</b></a></sup> if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
-<p><!--para 7-->
+<p><!--para 7 -->
EXAMPLE 1 The strncpy_s function can be used to copy a string without the danger that the result
will not be null terminated or that characters will be written past the end of the destination array.
<pre>
<a name="K.3.7.2.1" href="#K.3.7.2.1"><h5>K.3.7.2.1 The strcat_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
rsize_t s1max,
const char * restrict s2);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Let m denote the value s1max - strnlen_s(s1, s1max) upon entry to
strcat_s.
-<!--page 632 indent 4-->
-<p><!--para 3-->
+<!--page 632 -->
+<p><!--para 3 -->
Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX.
s1max shall not equal zero. m shall not equal zero.<sup><a href="#note408"><b>408)</b></a></sup> m shall be greater than
strnlen_s(s2, m). Copying shall not take place between objects that overlap.
-<p><!--para 4-->
+<p><!--para 4 -->
If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
greater than zero and not greater than RSIZE_MAX, then strcat_s sets s1[0] to the
null character.
<h6>Description</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The strcat_s function appends a copy of the string pointed to by s2 (including the
terminating null character) to the end of the string pointed to by s1. The initial character
from s2 overwrites the null character at the end of s1.
-<p><!--para 6-->
+<p><!--para 6 -->
All elements following the terminating null character (if any) written by strcat_s in
the array of s1max characters pointed to by s1 take unspecified values when
strcat_s returns.<sup><a href="#note409"><b>409)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The strcat_s function returns zero<sup><a href="#note410"><b>410)</b></a></sup> if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
<a name="K.3.7.2.2" href="#K.3.7.2.2"><h5>K.3.7.2.2 The strncat_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
const char * restrict s2,
rsize_t n);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Let m denote the value s1max - strnlen_s(s1, s1max) upon entry to
strncat_s.
-<p><!--para 3-->
+<p><!--para 3 -->
Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
RSIZE_MAX. s1max shall not equal zero. m shall not equal zero.<sup><a href="#note411"><b>411)</b></a></sup> If n is not less
-<!--page 633 indent 4-->
+<!--page 633 -->
than m, then m shall be greater than strnlen_s(s2, m). Copying shall not take
place between objects that overlap.
-<p><!--para 4-->
+<p><!--para 4 -->
If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
greater than zero and not greater than RSIZE_MAX, then strncat_s sets s1[0] to the
null character.
<h6>Description</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The strncat_s function appends not more than n successive characters (characters
that follow a null character are not copied) from the array pointed to by s2 to the end of
the string pointed to by s1. The initial character from s2 overwrites the null character at
the end of s1. If no null character was copied from s2, then s1[s1max-m+n] is set to
a null character.
-<p><!--para 6-->
+<p><!--para 6 -->
All elements following the terminating null character (if any) written by strncat_s in
the array of s1max characters pointed to by s1 take unspecified values when
strncat_s returns.<sup><a href="#note412"><b>412)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The strncat_s function returns zero<sup><a href="#note413"><b>413)</b></a></sup> if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
-<p><!--para 8-->
+<p><!--para 8 -->
EXAMPLE 1 The strncat_s function can be used to copy a string without the danger that the result
will not be null terminated or that characters will be written past the end of the destination array.
<pre>
-<!--page 634 indent 4-->
+<!--page 634 -->
After the second call r2 will have the value zero and s2 will contain the sequence hello\0.
After the third call r3 will have a nonzero value and s3 will contain the sequence \0.
After the fourth call r4 will have the value zero and s4 will contain the sequence abcdef\0.
<a name="K.3.7.3.1" href="#K.3.7.3.1"><h5>K.3.7.3.1 The strtok_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
const char * restrict s2,
char ** restrict ptr);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
None of s1max, s2, or ptr shall be a null pointer. If s1 is a null pointer, then *ptr
shall not be a null pointer. The value of *s1max shall not be greater than RSIZE_MAX.
The end of the token found shall occur within the first *s1max characters of s1 for the
first call, and shall occur within the first *s1max characters of where searching resumes
on subsequent calls.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the strtok_s function does not indirect
through the s1 or s2 pointers, and does not store a value in the object pointed to by ptr.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
A sequence of calls to the strtok_s function breaks the string pointed to by s1 into a
sequence of tokens, each of which is delimited by a character from the string pointed to
by s2. The fourth argument points to a caller-provided char pointer into which the
strtok_s function stores information necessary for it to continue scanning the same
string.
-<p><!--para 5-->
+<p><!--para 5 -->
The first call in a sequence has a non-null first argument and s1max points to an object
whose value is the number of elements in the character array pointed to by the first
argument. The first call stores an initial value in the object pointed to by ptr and
objects pointed to by s1max and ptr are required to have the values stored by the
previous call in the sequence, which are then updated. The separator string pointed to by
s2 may be different from call to call.
-<p><!--para 6-->
+<p><!--para 6 -->
The first call in the sequence searches the string pointed to by s1 for the first character
that is not contained in the current separator string pointed to by s2. If no such character
is found, then there are no tokens in the string pointed to by s1 and the strtok_s
function returns a null pointer. If such a character is found, it is the start of the first token.
-<!--page 635 indent 5-->
-<p><!--para 7-->
+<!--page 635 -->
+<p><!--para 7 -->
The strtok_s function then searches from there for the first character in s1 that is
contained in the current separator string. If no such character is found, the current token
extends to the end of the string pointed to by s1, and subsequent searches in the same
string for a token return a null pointer. If such a character is found, it is overwritten by a
null character, which terminates the current token.
-<p><!--para 8-->
+<p><!--para 8 -->
In all cases, the strtok_s function stores sufficient information in the pointer pointed
to by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer
value for ptr, shall start searching just past the element overwritten by a null character
(if any).
<h6>Returns</h6>
-<p><!--para 9-->
+<p><!--para 9 -->
The strtok_s function returns a pointer to the first character of a token, or a null
pointer if there is no token or there is a runtime-constraint violation.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
<a name="K.3.7.4.1" href="#K.3.7.4.1"><h5>K.3.7.4.1 The memset_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
errno_t memset_s(void *s, rsize_t smax, int c, rsize_t n)</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
s shall not be a null pointer. Neither smax nor n shall be greater than RSIZE_MAX. n
shall not be greater than smax.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and smax is not
greater than RSIZE_MAX, the memset_s function stores the value of c (converted to an
unsigned char) into each of the first smax characters of the object pointed to by s.
-<!--page 636 indent 4-->
+<!--page 636 -->
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The memset_s function copies the value of c (converted to an unsigned char) into
each of the first n characters of the object pointed to by s. Unlike memset, any call to
the memset_s function shall be evaluated strictly according to the rules of the abstract
assume that the memory indicated by s and n may be accessible in the future and thus
must contain the values indicated by c.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The memset_s function returns zero if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
<a name="K.3.7.4.2" href="#K.3.7.4.2"><h5>K.3.7.4.2 The strerror_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
errno_t strerror_s(char *s, rsize_t maxsize,
errno_t errnum);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
s shall not be a null pointer. maxsize shall not be greater than RSIZE_MAX.
maxsize shall not equal zero.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then the array (if any) pointed to by s is not
modified.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The strerror_s function maps the number in errnum to a locale-specific message
string. Typically, the values for errnum come from errno, but strerror_s shall
map any value of type int to a message.
-<p><!--para 5-->
+<p><!--para 5 -->
If the length of the desired string is less than maxsize, then the string is copied to the
array pointed to by s.
-<p><!--para 6-->
+<p><!--para 6 -->
Otherwise, if maxsize is greater than zero, then maxsize-1 characters are copied
from the string to the array pointed to by s and then s[maxsize-1] is set to the null
character. Then, if maxsize is greater than 3, then s[maxsize-2],
s[maxsize-3], and s[maxsize-4] are set to the character period (.).
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The strerror_s function returns zero if the length of the desired string was less than
maxsize and there was no runtime-constraint violation. Otherwise, the strerror_s
function returns a nonzero value.
-<!--page 637 indent 4-->
+<!--page 637 -->
<a name="K.3.7.4.3" href="#K.3.7.4.3"><h5>K.3.7.4.3 The strerrorlen_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
size_t strerrorlen_s(errno_t errnum);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strerrorlen_s function calculates the length of the (untruncated) locale-specific
message string that the strerror_s function maps to errnum.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
The strerrorlen_s function returns the number of characters (not including the null
character) in the full message string.
<a name="K.3.7.4.4" href="#K.3.7.4.4"><h5>K.3.7.4.4 The strnlen_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.23"><string.h></a>
size_t strnlen_s(const char *s, size_t maxsize);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The strnlen_s function computes the length of the string pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If s is a null pointer,<sup><a href="#note414"><b>414)</b></a></sup> then the strnlen_s function returns zero.
-<p><!--para 4-->
+<p><!--para 4 -->
Otherwise, the strnlen_s function returns the number of characters that precede the
terminating null character. If there is no null character in the first maxsize characters of
s then strnlen_s returns maxsize. At most the first maxsize characters of s shall
-<!--page 638 indent 4-->
+<!--page 638 -->
<h6>footnotes</h6>
<p><small><a name="note414" href="#note414">414)</a> Note that the strnlen_s function has no runtime-constraints. This lack of runtime-constraints
</small>
<a name="K.3.8" href="#K.3.8"><h4>K.3.8 Date and time <time.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.26"><time.h></a> defines two types.
-<p><!--para 2-->
+<p><!--para 2 -->
The types are
<pre>
errno_t</pre>
which is the type size_t.
<a name="K.3.8.1" href="#K.3.8.1"><h5>K.3.8.1 Components of time</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
A broken-down time is normalized if the values of the members of the tm structure are in
their normal rages.<sup><a href="#note415"><b>415)</b></a></sup>
</small>
<a name="K.3.8.2" href="#K.3.8.2"><h5>K.3.8.2 Time conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Like the strftime function, the asctime_s and ctime_s functions do not return a
pointer to a static object, and other library functions are permitted to call them.
<a name="K.3.8.2.1" href="#K.3.8.2.1"><h5>K.3.8.2.1 The asctime_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.26"><time.h></a>
errno_t asctime_s(char *s, rsize_t maxsize,
const struct tm *timeptr);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor timeptr shall be a null pointer. maxsize shall not be less than 26 and
shall not be greater than RSIZE_MAX. The broken-down time pointed to by timeptr
shall be normalized. The calendar year represented by the broken-down time pointed to
by timeptr shall not be less than calendar year 0 and shall not be greater than calendar
year 9999.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, there is no attempt to convert the time, and
s[0] is set to a null character if s is not a null pointer and maxsize is not zero and is
not greater than RSIZE_MAX.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The asctime_s function converts the normalized broken-down time in the structure
pointed to by timeptr into a 26 character (including the null character) string in the
-<!--page 639 indent 4-->
+<!--page 639 -->
form
<pre>
Sun Sep 16 01:03:52 1973\n\0</pre>
behavior. If you do not require the exact form of the result string produced by the
asctime_s function, consider using the strftime function instead.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The asctime_s function returns zero if the time was successfully converted and stored
into the array pointed to by s. Otherwise, it returns a nonzero value.
-<!--page 640 indent 4-->
+<!--page 640 -->
<a name="K.3.8.2.2" href="#K.3.8.2.2"><h5>K.3.8.2.2 The ctime_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.26"><time.h></a>
errno_t ctime_s(char *s, rsize_t maxsize,
const time_t *timer);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor timer shall be a null pointer. maxsize shall not be less than 26 and
shall not be greater than RSIZE_MAX.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, s[0] is set to a null character if s is not a null
pointer and maxsize is not equal zero and is not greater than RSIZE_MAX.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The ctime_s function converts the calendar time pointed to by timer to local time in
the form of a string. It is equivalent to
<pre>
behavior. If you do not require the exact form of the result string produced by the
ctime_s function, consider using the strftime function instead.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The ctime_s function returns zero if the time was successfully converted and stored
into the array pointed to by s. Otherwise, it returns a nonzero value.
<a name="K.3.8.2.3" href="#K.3.8.2.3"><h5>K.3.8.2.3 The gmtime_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.26"><time.h></a>
struct tm *gmtime_s(const time_t * restrict timer,
struct tm * restrict result);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither timer nor result shall be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, there is no attempt to convert the time.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The gmtime_s function converts the calendar time pointed to by timer into a broken-
down time, expressed as UTC. The broken-down time is stored in the structure pointed
-<!--page 641 indent 4-->
+<!--page 641 -->
to by result.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The gmtime_s function returns result, or a null pointer if the specified time cannot
be converted to UTC or there is a runtime-constraint violation.
<a name="K.3.8.2.4" href="#K.3.8.2.4"><h5>K.3.8.2.4 The localtime_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.26"><time.h></a>
struct tm *localtime_s(const time_t * restrict timer,
struct tm * restrict result);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither timer nor result shall be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, there is no attempt to convert the time.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The localtime_s function converts the calendar time pointed to by timer into a
broken-down time, expressed as local time. The broken-down time is stored in the
structure pointed to by result.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The localtime_s function returns result, or a null pointer if the specified time
cannot be converted to local time or there is a runtime-constraint violation.
<a name="K.3.9" href="#K.3.9"><h4>K.3.9 Extended multibyte and wide character utilities <wchar.h></h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
The header <a href="#7.28"><wchar.h></a> defines two types.
-<p><!--para 2-->
+<p><!--para 2 -->
The types are
<pre>
errno_t</pre>
<pre>
rsize_t</pre>
which is the type size_t.
-<p><!--para 3-->
+<p><!--para 3 -->
Unless explicitly stated otherwise, if the execution of a function described in this
subclause causes copying to take place between objects that overlap, the objects take on
unspecified values.
-<!--page 642 indent 4-->
+<!--page 642 -->
<a name="K.3.9.1" href="#K.3.9.1"><h5>K.3.9.1 Formatted wide character input/output functions</h5></a>
<a name="K.3.9.1.1" href="#K.3.9.1.1"><h5>K.3.9.1.1 The fwprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
int fwprintf_s(FILE * restrict stream,
const wchar_t * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither stream nor format shall be a null pointer. The %n specifier<sup><a href="#note416"><b>416)</b></a></sup> (modified or
not by flags, field width, or precision) shall not appear in the wide string pointed to by
format. Any argument to fwprintf_s corresponding to a %s specifier shall not be a
null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the fwprintf_s function does not attempt to
produce further output, and it is unspecified to what extent fwprintf_s produced
output before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The fwprintf_s function is equivalent to the fwprintf function except for the
explicit runtime-constraints listed above.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The fwprintf_s function returns the number of wide characters transmitted, or a
negative value if an output error, encoding error, or runtime-constraint violation occurred.
<a name="K.3.9.1.2" href="#K.3.9.1.2"><h5>K.3.9.1.2 The fwscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.21"><stdio.h></a>
int fwscanf_s(FILE * restrict stream,
const wchar_t * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither stream nor format shall be a null pointer. Any argument indirected though in
order to store converted input shall not be a null pointer.
-<!--page 643 indent 4-->
-<p><!--para 3-->
+<!--page 643 -->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the fwscanf_s function does not attempt to
perform further input, and it is unspecified to what extent fwscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The fwscanf_s function is equivalent to fwscanf except that the c, s, and [
conversion specifiers apply to a pair of arguments (unless assignment suppression is
indicated by a *). The first of these arguments is the same as for fwscanf. That
type size_t and gives the number of elements in the array pointed to by the first
argument of the pair. If the first argument points to a scalar object, it is considered to be
an array of one element.<sup><a href="#note417"><b>417)</b></a></sup>
-<p><!--para 5-->
+<p><!--para 5 -->
A matching failure occurs if the number of elements in a receiving object is insufficient to
hold the converted input (including any trailing null character).
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The fwscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
fwscanf_s function returns the number of input items assigned, which can be fewer
<a name="K.3.9.1.3" href="#K.3.9.1.3"><h5>K.3.9.1.3 The snwprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
rsize_t n,
const wchar_t * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
than RSIZE_MAX. The %n specifier<sup><a href="#note418"><b>418)</b></a></sup> (modified or not by flags, field width, or
-<!--page 644 indent 4-->
+<!--page 644 -->
precision) shall not appear in the wide string pointed to by format. Any argument to
snwprintf_s corresponding to a %s specifier shall not be a null pointer. No encoding
error shall occur.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
than zero and less than RSIZE_MAX, then the snwprintf_s function sets s[0] to the
null wide character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The snwprintf_s function is equivalent to the swprintf function except for the
explicit runtime-constraints listed above.
-<p><!--para 5-->
+<p><!--para 5 -->
The snwprintf_s function, unlike swprintf_s, will truncate the result to fit within
the array pointed to by s.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The snwprintf_s function returns the number of wide characters that would have
been written had n been sufficiently large, not counting the terminating wide null
character, or a negative value if a runtime-constraint violation occurred. Thus, the null-
<a name="K.3.9.1.4" href="#K.3.9.1.4"><h5>K.3.9.1.4 The swprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
int swprintf_s(wchar_t * restrict s, rsize_t n,
const wchar_t * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
than RSIZE_MAX. The number of wide characters (including the trailing null) required
for the result to be written to the array pointed to by s shall not be greater than n. The %n
%s specifier shall not be a null pointer. No encoding error shall occur.
-<!--page 645 indent 4-->
-<p><!--para 3-->
+<!--page 645 -->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
than zero and less than RSIZE_MAX, then the swprintf_s function sets s[0] to the
null wide character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The swprintf_s function is equivalent to the swprintf function except for the
explicit runtime-constraints listed above.
-<p><!--para 5-->
+<p><!--para 5 -->
The swprintf_s function, unlike snwprintf_s, treats a result too big for the array
pointed to by s as a runtime-constraint violation.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
If no runtime-constraint violation occurred, the swprintf_s function returns the
number of wide characters written in the array, not counting the terminating null wide
character. If an encoding error occurred or if n or more wide characters are requested to
<a name="K.3.9.1.5" href="#K.3.9.1.5"><h5>K.3.9.1.5 The swscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
int swscanf_s(const wchar_t * restrict s,
const wchar_t * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. Any argument indirected though in order
to store converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the swscanf_s function does not attempt to
perform further input, and it is unspecified to what extent swscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The swscanf_s function is equivalent to fwscanf_s, except that the argument s
specifies a wide string from which the input is to be obtained, rather than from a stream.
Reaching the end of the wide string is equivalent to encountering end-of-file for the
fwscanf_s function.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The swscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
swscanf_s function returns the number of input items assigned, which can be fewer
than provided for, or even zero, in the event of an early matching failure.
-<!--page 646 indent 4-->
+<!--page 646 -->
<a name="K.3.9.1.6" href="#K.3.9.1.6"><h5>K.3.9.1.6 The vfwprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither stream nor format shall be a null pointer. The %n specifier<sup><a href="#note420"><b>420)</b></a></sup> (modified or
not by flags, field width, or precision) shall not appear in the wide string pointed to by
format. Any argument to vfwprintf_s corresponding to a %s specifier shall not be
a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vfwprintf_s function does not attempt
to produce further output, and it is unspecified to what extent vfwprintf_s produced
output before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vfwprintf_s function is equivalent to the vfwprintf function except for the
explicit runtime-constraints listed above.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vfwprintf_s function returns the number of wide characters transmitted, or a
negative value if an output error, encoding error, or runtime-constraint violation occurred.
<a name="K.3.9.1.7" href="#K.3.9.1.7"><h5>K.3.9.1.7 The vfwscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
-<!--page 647 indent 4-->
+<!--page 647 -->
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither stream nor format shall be a null pointer. Any argument indirected though in
order to store converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vfwscanf_s function does not attempt to
perform further input, and it is unspecified to what extent vfwscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vfwscanf_s function is equivalent to fwscanf_s, with the variable argument
list replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vfwscanf_s function does not invoke the
va_end macro.<sup><a href="#note421"><b>421)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vfwscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
vfwscanf_s function returns the number of input items assigned, which can be fewer
<a name="K.3.9.1.8" href="#K.3.9.1.8"><h5>K.3.9.1.8 The vsnwprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
than RSIZE_MAX. The %n specifier<sup><a href="#note422"><b>422)</b></a></sup> (modified or not by flags, field width, or
precision) shall not appear in the wide string pointed to by format. Any argument to
vsnwprintf_s corresponding to a %s specifier shall not be a null pointer. No
encoding error shall occur.
-<!--page 648 indent 4-->
-<p><!--para 3-->
+<!--page 648 -->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
than zero and less than RSIZE_MAX, then the vsnwprintf_s function sets s[0] to
the null wide character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vsnwprintf_s function is equivalent to the vswprintf function except for the
explicit runtime-constraints listed above.
-<p><!--para 5-->
+<p><!--para 5 -->
The vsnwprintf_s function, unlike vswprintf_s, will truncate the result to fit
within the array pointed to by s.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The vsnwprintf_s function returns the number of wide characters that would have
been written had n been sufficiently large, not counting the terminating null character, or
a negative value if a runtime-constraint violation occurred. Thus, the null-terminated
<a name="K.3.9.1.9" href="#K.3.9.1.9"><h5>K.3.9.1.9 The vswprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. n shall neither equal zero nor be greater
than RSIZE_MAX. The number of wide characters (including the trailing null) required
for the result to be written to the array pointed to by s shall not be greater than n. The %n
specifier<sup><a href="#note423"><b>423)</b></a></sup> (modified or not by flags, field width, or precision) shall not appear in the
wide string pointed to by format. Any argument to vswprintf_s corresponding to a
%s specifier shall not be a null pointer. No encoding error shall occur.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s is not a null pointer and n is greater
than zero and less than RSIZE_MAX, then the vswprintf_s function sets s[0] to the
null wide character.
-<!--page 649 indent 4-->
+<!--page 649 -->
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vswprintf_s function is equivalent to the vswprintf function except for the
explicit runtime-constraints listed above.
-<p><!--para 5-->
+<p><!--para 5 -->
The vswprintf_s function, unlike vsnwprintf_s, treats a result too big for the
array pointed to by s as a runtime-constraint violation.
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
If no runtime-constraint violation occurred, the vswprintf_s function returns the
number of wide characters written in the array, not counting the terminating null wide
character. If an encoding error occurred or if n or more wide characters are requested to
<a name="K.3.9.1.10" href="#K.3.9.1.10"><h5>K.3.9.1.10 The vswscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
const wchar_t * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s nor format shall be a null pointer. Any argument indirected though in order
to store converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vswscanf_s function does not attempt to
perform further input, and it is unspecified to what extent vswscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vswscanf_s function is equivalent to swscanf_s, with the variable argument
list replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vswscanf_s function does not invoke the
-<!--page 650 indent 4-->
+<!--page 650 -->
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vswscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
vswscanf_s function returns the number of input items assigned, which can be fewer
<a name="K.3.9.1.11" href="#K.3.9.1.11"><h5>K.3.9.1.11 The vwprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
int vwprintf_s(const wchar_t * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
format shall not be a null pointer. The %n specifier<sup><a href="#note425"><b>425)</b></a></sup> (modified or not by flags, field
width, or precision) shall not appear in the wide string pointed to by format. Any
argument to vwprintf_s corresponding to a %s specifier shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vwprintf_s function does not attempt to
produce further output, and it is unspecified to what extent vwprintf_s produced
output before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vwprintf_s function is equivalent to the vwprintf function except for the
explicit runtime-constraints listed above.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vwprintf_s function returns the number of wide characters transmitted, or a
negative value if an output error, encoding error, or runtime-constraint violation occurred.
-<!--page 651 indent 4-->
+<!--page 651 -->
<h6>footnotes</h6>
<p><small><a name="note425" href="#note425">425)</a> It is not a runtime-constraint violation for the wide characters %n to appear in sequence in the wide
<a name="K.3.9.1.12" href="#K.3.9.1.12"><h5>K.3.9.1.12 The vwscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.16"><stdarg.h></a>
int vwscanf_s(const wchar_t * restrict format,
va_list arg);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
format shall not be a null pointer. Any argument indirected though in order to store
converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the vwscanf_s function does not attempt to
perform further input, and it is unspecified to what extent vwscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The vwscanf_s function is equivalent to wscanf_s, with the variable argument list
replaced by arg, which shall have been initialized by the va_start macro (and
possibly subsequent va_arg calls). The vwscanf_s function does not invoke the
va_end macro.<sup><a href="#note426"><b>426)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The vwscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
vwscanf_s function returns the number of input items assigned, which can be fewer
<a name="K.3.9.1.13" href="#K.3.9.1.13"><h5>K.3.9.1.13 The wprintf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
int wprintf_s(const wchar_t * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
format shall not be a null pointer. The %n specifier<sup><a href="#note427"><b>427)</b></a></sup> (modified or not by flags, field
-<!--page 652 indent 4-->
+<!--page 652 -->
width, or precision) shall not appear in the wide string pointed to by format. Any
argument to wprintf_s corresponding to a %s specifier shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the wprintf_s function does not attempt to
produce further output, and it is unspecified to what extent wprintf_s produced output
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The wprintf_s function is equivalent to the wprintf function except for the explicit
runtime-constraints listed above.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The wprintf_s function returns the number of wide characters transmitted, or a
negative value if an output error, encoding error, or runtime-constraint violation occurred.
<a name="K.3.9.1.14" href="#K.3.9.1.14"><h5>K.3.9.1.14 The wscanf_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
int wscanf_s(const wchar_t * restrict format, ...);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
format shall not be a null pointer. Any argument indirected though in order to store
converted input shall not be a null pointer.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the wscanf_s function does not attempt to
perform further input, and it is unspecified to what extent wscanf_s performed input
before discovering the runtime-constraint violation.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The wscanf_s function is equivalent to fwscanf_s with the argument stdin
interposed before the arguments to wscanf_s.
<h6>Returns</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The wscanf_s function returns the value of the macro EOF if an input failure occurs
before any conversion or if there is a runtime-constraint violation. Otherwise, the
wscanf_s function returns the number of input items assigned, which can be fewer than
provided for, or even zero, in the event of an early matching failure.
-<!--page 653 indent 4-->
+<!--page 653 -->
<a name="K.3.9.2" href="#K.3.9.2"><h5>K.3.9.2 General wide string utilities</h5></a>
<a name="K.3.9.2.1.1" href="#K.3.9.2.1.1"><h5>K.3.9.2.1.1 The wcscpy_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
rsize_t s1max,
const wchar_t * restrict s2);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX.
s1max shall not equal zero. s1max shall be greater than wcsnlen_s(s2, s1max).
Copying shall not take place between objects that overlap.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
greater than zero and not greater than RSIZE_MAX, then wcscpy_s sets s1[0] to the
null wide character.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
The wcscpy_s function copies the wide string pointed to by s2 (including the
terminating null wide character) into the array pointed to by s1.
-<p><!--para 5-->
+<p><!--para 5 -->
All elements following the terminating null wide character (if any) written by
wcscpy_s in the array of s1max wide characters pointed to by s1 take unspecified
values when wcscpy_s returns.<sup><a href="#note428"><b>428)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 6-->
+<p><!--para 6 -->
The wcscpy_s function returns zero<sup><a href="#note429"><b>429)</b></a></sup> if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
-<!--page 654 indent 5-->
+<!--page 654 -->
<h6>footnotes</h6>
<p><small><a name="note428" href="#note428">428)</a> This allows an implementation to copy wide characters from s2 to s1 while simultaneously checking
<a name="K.3.9.2.1.2" href="#K.3.9.2.1.2"><h5>K.3.9.2.1.2 The wcsncpy_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
const wchar_t * restrict s2,
rsize_t n);</pre>
Runtime-constraints
-<p><!--para 8-->
+<p><!--para 8 -->
Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
RSIZE_MAX. s1max shall not equal zero. If n is not less than s1max, then s1max
shall be greater than wcsnlen_s(s2, s1max). Copying shall not take place between
objects that overlap.
-<p><!--para 9-->
+<p><!--para 9 -->
If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
greater than zero and not greater than RSIZE_MAX, then wcsncpy_s sets s1[0] to the
null wide character.
<h6>Description</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
The wcsncpy_s function copies not more than n successive wide characters (wide
characters that follow a null wide character are not copied) from the array pointed to by
s2 to the array pointed to by s1. If no null wide character was copied from s2, then
s1[n] is set to a null wide character.
-<p><!--para 11-->
+<p><!--para 11 -->
All elements following the terminating null wide character (if any) written by
wcsncpy_s in the array of s1max wide characters pointed to by s1 take unspecified
values when wcsncpy_s returns.<sup><a href="#note430"><b>430)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 12-->
+<p><!--para 12 -->
The wcsncpy_s function returns zero<sup><a href="#note431"><b>431)</b></a></sup> if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
-<p><!--para 13-->
+<p><!--para 13 -->
EXAMPLE 1 The wcsncpy_s function can be used to copy a wide string without the danger that the
result will not be null terminated or that wide characters will be written past the end of the destination
array.
-<!--page 655 indent 5-->
+<!--page 655 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
<a name="K.3.9.2.1.3" href="#K.3.9.2.1.3"><h5>K.3.9.2.1.3 The wmemcpy_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 14-->
+<p><!--para 14 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
const wchar_t * restrict s2,
rsize_t n);</pre>
Runtime-constraints
-<p><!--para 15-->
+<p><!--para 15 -->
Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
RSIZE_MAX. n shall not be greater than s1max. Copying shall not take place between
objects that overlap.
-<p><!--para 16-->
+<p><!--para 16 -->
If there is a runtime-constraint violation, the wmemcpy_s function stores zeros in the
first s1max wide characters of the object pointed to by s1 if s1 is not a null pointer and
s1max is not greater than RSIZE_MAX.
<h6>Description</h6>
-<p><!--para 17-->
+<p><!--para 17 -->
The wmemcpy_s function copies n successive wide characters from the object pointed
to by s2 into the object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 18-->
+<p><!--para 18 -->
The wmemcpy_s function returns zero if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
-<!--page 656 indent 5-->
+<!--page 656 -->
<a name="K.3.9.2.1.4" href="#K.3.9.2.1.4"><h5>K.3.9.2.1.4 The wmemmove_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 19-->
+<p><!--para 19 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
errno_t wmemmove_s(wchar_t *s1, rsize_t s1max,
const wchar_t *s2, rsize_t n);</pre>
Runtime-constraints
-<p><!--para 20-->
+<p><!--para 20 -->
Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
RSIZE_MAX. n shall not be greater than s1max.
-<p><!--para 21-->
+<p><!--para 21 -->
If there is a runtime-constraint violation, the wmemmove_s function stores zeros in the
first s1max wide characters of the object pointed to by s1 if s1 is not a null pointer and
s1max is not greater than RSIZE_MAX.
<h6>Description</h6>
-<p><!--para 22-->
+<p><!--para 22 -->
The wmemmove_s function copies n successive wide characters from the object pointed
to by s2 into the object pointed to by s1. This copying takes place as if the n wide
characters from the object pointed to by s2 are first copied into a temporary array of n
wide characters that does not overlap the objects pointed to by s1 or s2, and then the n
wide characters from the temporary array are copied into the object pointed to by s1.
<h6>Returns</h6>
-<p><!--para 23-->
+<p><!--para 23 -->
The wmemmove_s function returns zero if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
<a name="K.3.9.2.2.1" href="#K.3.9.2.2.1"><h5>K.3.9.2.2.1 The wcscat_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
rsize_t s1max,
const wchar_t * restrict s2);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
Let m denote the value s1max - wcsnlen_s(s1, s1max) upon entry to
wcscat_s.
-<p><!--para 3-->
+<p><!--para 3 -->
Neither s1 nor s2 shall be a null pointer. s1max shall not be greater than RSIZE_MAX.
s1max shall not equal zero. m shall not equal zero.<sup><a href="#note432"><b>432)</b></a></sup> m shall be greater than
wcsnlen_s(s2, m). Copying shall not take place between objects that overlap.
-<!--page 657 indent 5-->
-<p><!--para 4-->
+<!--page 657 -->
+<p><!--para 4 -->
If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
greater than zero and not greater than RSIZE_MAX, then wcscat_s sets s1[0] to the
null wide character.
<h6>Description</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The wcscat_s function appends a copy of the wide string pointed to by s2 (including
the terminating null wide character) to the end of the wide string pointed to by s1. The
initial wide character from s2 overwrites the null wide character at the end of s1.
-<p><!--para 6-->
+<p><!--para 6 -->
All elements following the terminating null wide character (if any) written by
wcscat_s in the array of s1max wide characters pointed to by s1 take unspecified
values when wcscat_s returns.<sup><a href="#note433"><b>433)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 7-->
+<p><!--para 7 -->
The wcscat_s function returns zero<sup><a href="#note434"><b>434)</b></a></sup> if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
<a name="K.3.9.2.2.2" href="#K.3.9.2.2.2"><h5>K.3.9.2.2.2 The wcsncat_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
const wchar_t * restrict s2,
rsize_t n);</pre>
Runtime-constraints
-<p><!--para 9-->
+<p><!--para 9 -->
Let m denote the value s1max - wcsnlen_s(s1, s1max) upon entry to
wcsncat_s.
-<p><!--para 10-->
+<p><!--para 10 -->
Neither s1 nor s2 shall be a null pointer. Neither s1max nor n shall be greater than
RSIZE_MAX. s1max shall not equal zero. m shall not equal zero.<sup><a href="#note435"><b>435)</b></a></sup> If n is not less
than m, then m shall be greater than wcsnlen_s(s2, m). Copying shall not take
place between objects that overlap.
-<!--page 658 indent 5-->
-<p><!--para 11-->
+<!--page 658 -->
+<p><!--para 11 -->
If there is a runtime-constraint violation, then if s1 is not a null pointer and s1max is
greater than zero and not greater than RSIZE_MAX, then wcsncat_s sets s1[0] to the
null wide character.
<h6>Description</h6>
-<p><!--para 12-->
+<p><!--para 12 -->
The wcsncat_s function appends not more than n successive wide characters (wide
characters that follow a null wide character are not copied) from the array pointed to by
s2 to the end of the wide string pointed to by s1. The initial wide character from s2
overwrites the null wide character at the end of s1. If no null wide character was copied
from s2, then s1[s1max-m+n] is set to a null wide character.
-<p><!--para 13-->
+<p><!--para 13 -->
All elements following the terminating null wide character (if any) written by
wcsncat_s in the array of s1max wide characters pointed to by s1 take unspecified
values when wcsncat_s returns.<sup><a href="#note436"><b>436)</b></a></sup>
<h6>Returns</h6>
-<p><!--para 14-->
+<p><!--para 14 -->
The wcsncat_s function returns zero<sup><a href="#note437"><b>437)</b></a></sup> if there was no runtime-constraint violation.
Otherwise, a nonzero value is returned.
-<p><!--para 15-->
+<p><!--para 15 -->
EXAMPLE 1 The wcsncat_s function can be used to copy a wide string without the danger that the
result will not be null terminated or that wide characters will be written past the end of the destination
array.
-<!--page 659 indent 4-->
+<!--page 659 -->
<h6>footnotes</h6>
<p><small><a name="note435" href="#note435">435)</a> Zero means that s1 was not null terminated upon entry to wcsncat_s.
<a name="K.3.9.2.3.1" href="#K.3.9.2.3.1"><h5>K.3.9.2.3.1 The wcstok_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
const wchar_t * restrict s2,
wchar_t ** restrict ptr);</pre>
Runtime-constraints
-<p><!--para 2-->
+<p><!--para 2 -->
None of s1max, s2, or ptr shall be a null pointer. If s1 is a null pointer, then *ptr
shall not be a null pointer. The value of *s1max shall not be greater than RSIZE_MAX.
The end of the token found shall occur within the first *s1max wide characters of s1 for
the first call, and shall occur within the first *s1max wide characters of where searching
resumes on subsequent calls.
-<p><!--para 3-->
+<p><!--para 3 -->
If there is a runtime-constraint violation, the wcstok_s function does not indirect
through the s1 or s2 pointers, and does not store a value in the object pointed to by ptr.
<h6>Description</h6>
-<p><!--para 4-->
+<p><!--para 4 -->
A sequence of calls to the wcstok_s function breaks the wide string pointed to by s1
into a sequence of tokens, each of which is delimited by a wide character from the wide
string pointed to by s2. The fourth argument points to a caller-provided wchar_t
pointer into which the wcstok_s function stores information necessary for it to
continue scanning the same wide string.
-<p><!--para 5-->
+<p><!--para 5 -->
The first call in a sequence has a non-null first argument and s1max points to an object
whose value is the number of elements in the wide character array pointed to by the first
argument. The first call stores an initial value in the object pointed to by ptr and
objects pointed to by s1max and ptr are required to have the values stored by the
previous call in the sequence, which are then updated. The separator wide string pointed
to by s2 may be different from call to call.
-<p><!--para 6-->
+<p><!--para 6 -->
The first call in the sequence searches the wide string pointed to by s1 for the first wide
character that is not contained in the current separator wide string pointed to by s2. If no
such wide character is found, then there are no tokens in the wide string pointed to by s1
and the wcstok_s function returns a null pointer. If such a wide character is found, it is
the start of the first token.
-<!--page 660 indent 5-->
-<p><!--para 7-->
+<!--page 660 -->
+<p><!--para 7 -->
The wcstok_s function then searches from there for the first wide character in s1 that
is contained in the current separator wide string. If no such wide character is found, the
current token extends to the end of the wide string pointed to by s1, and subsequent
searches in the same wide string for a token return a null pointer. If such a wide character
is found, it is overwritten by a null wide character, which terminates the current token.
-<p><!--para 8-->
+<p><!--para 8 -->
In all cases, the wcstok_s function stores sufficient information in the pointer pointed
to by ptr so that subsequent calls, with a null pointer for s1 and the unmodified pointer
value for ptr, shall start searching just past the element overwritten by a null wide
character (if any).
<h6>Returns</h6>
-<p><!--para 9-->
+<p><!--para 9 -->
The wcstok_s function returns a pointer to the first wide character of a token, or a null
pointer if there is no token or there is a runtime-constraint violation.
-<p><!--para 10-->
+<p><!--para 10 -->
EXAMPLE
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
<a name="K.3.9.2.4.1" href="#K.3.9.2.4.1"><h5>K.3.9.2.4.1 The wcsnlen_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 1-->
+<p><!--para 1 -->
<pre>
#define __STDC_WANT_LIB_EXT1__ 1
#include <a href="#7.28"><wchar.h></a>
size_t wcsnlen_s(const wchar_t *s, size_t maxsize);</pre>
<h6>Description</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
The wcsnlen_s function computes the length of the wide string pointed to by s.
<h6>Returns</h6>
-<p><!--para 3-->
+<p><!--para 3 -->
If s is a null pointer,<sup><a href="#note438"><b>438)</b></a></sup> then the wcsnlen_s function returns zero.
-<p><!--para 4-->
+<p><!--para 4 -->
Otherwise, the wcsnlen_s function returns the number of wide characters that precede
the terminating null wide character. If there is no null wide character in the first
maxsize wide characters of s then wcsnlen_s returns maxsize. At most the first
-<!--page 661 indent 4-->
+<!--page 661 -->
maxsize wide characters of s shall be accessed by wcsnlen_s.
<h6>footnotes</h6>
<a name="K.3.9.3" href="#K.3.9.3"><h5>K.3.9.3 Extended multibyte/wide character conversion utilities</h5></a>
<a name="K.3.9.3.1" href="#K.3.9.3.1"><h5>K.3.9.3.1 Restartable multibyte/wide character conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Unlike wcrtomb, wcrtomb_s does not permit the ps parameter (the pointer to the
conversion state) to be a null pointer.
<a name="K.3.9.3.1.1" href="#K.3.9.3.1.1"><h5>K.3.9.3.1.1 The wcrtomb_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
errno_t wcrtomb_s(size_t * restrict retval,
char * restrict s, rsize_t smax,
wchar_t wc, mbstate_t * restrict ps);</pre>
Runtime-constraints
-<p><!--para 3-->
+<p><!--para 3 -->
Neither retval nor ps shall be a null pointer. If s is not a null pointer, then smax
shall not equal zero and shall not be greater than RSIZE_MAX. If s is not a null pointer,
then smax shall be not be less than the number of bytes to be stored in the array pointed
to by s. If s is a null pointer, then smax shall equal zero.
-<p><!--para 4-->
+<p><!--para 4 -->
If there is a runtime-constraint violation, then wcrtomb_s does the following. If s is
not a null pointer and smax is greater than zero and not greater than RSIZE_MAX, then
wcrtomb_s sets s[0] to the null character. If retval is not a null pointer, then
wcrtomb_s sets *retval to (size_t)(-1).
<h6>Description</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
If s is a null pointer, the wcrtomb_s function is equivalent to the call
<pre>
wcrtomb_s(&retval, buf, sizeof buf, L'\0', ps)</pre>
where retval and buf are internal variables of the appropriate types, and the size of
buf is greater than MB_CUR_MAX.
-<p><!--para 6-->
+<p><!--para 6 -->
If s is not a null pointer, the wcrtomb_s function determines the number of bytes
needed to represent the multibyte character that corresponds to the wide character given
by wc (including any shift sequences), and stores the multibyte character representation
sequence needed to restore the initial shift state; the resulting state described is the initial
conversion state.
-<!--page 662 indent 4-->
-<p><!--para 7-->
+<!--page 662 -->
+<p><!--para 7 -->
If wc does not correspond to a valid multibyte character, an encoding error occurs: the
wcrtomb_s function stores the value (size_t)(-1) into *retval and the
conversion state is unspecified. Otherwise, the wcrtomb_s function stores into
*retval the number of bytes (including any shift sequences) stored in the array pointed
to by s.
<h6>Returns</h6>
-<p><!--para 8-->
+<p><!--para 8 -->
The wcrtomb_s function returns zero if no runtime-constraint violation and no
encoding error occurred. Otherwise, a nonzero value is returned.
<a name="K.3.9.3.2" href="#K.3.9.3.2"><h5>K.3.9.3.2 Restartable multibyte/wide string conversion functions</h5></a>
-<p><!--para 1-->
+<p><!--para 1 -->
Unlike mbsrtowcs and wcsrtombs, mbsrtowcs_s and wcsrtombs_s do not
permit the ps parameter (the pointer to the conversion state) to be a null pointer.
<a name="K.3.9.3.2.1" href="#K.3.9.3.2.1"><h5>K.3.9.3.2.1 The mbsrtowcs_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 2-->
+<p><!--para 2 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
errno_t mbsrtowcs_s(size_t * restrict retval,
const char ** restrict src, rsize_t len,
mbstate_t * restrict ps);</pre>
Runtime-constraints
-<p><!--para 3-->
+<p><!--para 3 -->
None of retval, src, *src, or ps shall be null pointers. If dst is not a null pointer,
then neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null
pointer, then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall
not equal zero. If dst is not a null pointer and len is not less than dstmax, then a null
character shall occur within the first dstmax multibyte characters of the array pointed to
by *src.
-<p><!--para 4-->
+<p><!--para 4 -->
If there is a runtime-constraint violation, then mbsrtowcs_s does the following. If
retval is not a null pointer, then mbsrtowcs_s sets *retval to (size_t)(-1).
If dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX,
then mbsrtowcs_s sets dst[0] to the null wide character.
<h6>Description</h6>
-<p><!--para 5-->
+<p><!--para 5 -->
The mbsrtowcs_s function converts a sequence of multibyte characters that begins in
the conversion state described by the object pointed to by ps, from the array indirectly
pointed to by src into a sequence of corresponding wide characters. If dst is not a null
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
-<!--page 663 indent 5-->
+<!--page 663 -->
characters have been stored into the array pointed to by dst.<sup><a href="#note439"><b>439)</b></a></sup> If dst is not a null
pointer and no null wide character was stored into the array pointed to by dst, then
dst[len] is set to the null wide character. Each conversion takes place as if by a call
to the mbrtowc function.
-<p><!--para 6-->
+<p><!--para 6 -->
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
just past the last multibyte character converted (if any). If conversion stopped due to
reaching a terminating null character and if dst is not a null pointer, the resulting state
described is the initial conversion state.
-<p><!--para 7-->
+<p><!--para 7 -->
Regardless of whether dst is or is not a null pointer, if the input conversion encounters a
sequence of bytes that do not form a valid multibyte character, an encoding error occurs:
the mbsrtowcs_s function stores the value (size_t)(-1) into *retval and the
conversion state is unspecified. Otherwise, the mbsrtowcs_s function stores into
*retval the number of multibyte characters successfully converted, not including the
terminating null character (if any).
-<p><!--para 8-->
+<p><!--para 8 -->
All elements following the terminating null wide character (if any) written by
mbsrtowcs_s in the array of dstmax wide characters pointed to by dst take
unspecified values when mbsrtowcs_s returns.<sup><a href="#note440"><b>440)</b></a></sup>
-<p><!--para 9-->
+<p><!--para 9 -->
If copying takes place between objects that overlap, the objects take on unspecified
values.
<h6>Returns</h6>
-<p><!--para 10-->
+<p><!--para 10 -->
The mbsrtowcs_s function returns zero if no runtime-constraint violation and no
encoding error occurred. Otherwise, a nonzero value is returned.
<a name="K.3.9.3.2.2" href="#K.3.9.3.2.2"><h5>K.3.9.3.2.2 The wcsrtombs_s function</h5></a>
<h6>Synopsis</h6>
-<p><!--para 11-->
+<p><!--para 11 -->
<pre>
#include <a href="#7.28"><wchar.h></a>
errno_t wcsrtombs_s(size_t * restrict retval,
-<!--page 664 indent 5-->
+<!--page 664 -->
Runtime-constraints
-<p><!--para 12-->
+<p><!--para 12 -->
None of retval, src, *src, or ps shall be null pointers. If dst is not a null pointer,
then neither len nor dstmax shall be greater than RSIZE_MAX. If dst is a null
pointer, then dstmax shall equal zero. If dst is not a null pointer, then dstmax shall
not equal zero. If dst is not a null pointer and len is not less than dstmax, then the
conversion shall have been stopped (see below) because a terminating null wide character
was reached or because an encoding error occurred.
-<p><!--para 13-->
+<p><!--para 13 -->
If there is a runtime-constraint violation, then wcsrtombs_s does the following. If
retval is not a null pointer, then wcsrtombs_s sets *retval to (size_t)(-1).
If dst is not a null pointer and dstmax is greater than zero and less than RSIZE_MAX,
then wcsrtombs_s sets dst[0] to the null character.
<h6>Description</h6>
-<p><!--para 14-->
+<p><!--para 14 -->
The wcsrtombs_s function converts a sequence of wide characters from the array
indirectly pointed to by src into a sequence of corresponding multibyte characters that
begins in the conversion state described by the object pointed to by ps. If dst is not a
pointer, then a null character is stored into the array pointed to by dst immediately
following any multibyte characters already stored. Each conversion takes place as if by a
call to the wcrtomb function.<sup><a href="#note441"><b>441)</b></a></sup>
-<p><!--para 15-->
+<p><!--para 15 -->
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
conversion state.
-<!--page 665 indent 5-->
-<p><!--para 16-->
+<!--page 665 -->
+<p><!--para 16 -->
Regardless of whether dst is or is not a null pointer, if the input conversion encounters a
wide character that does not correspond to a valid multibyte character, an encoding error
occurs: the wcsrtombs_s function stores the value (size_t)(-1) into *retval
and the conversion state is unspecified. Otherwise, the wcsrtombs_s function stores
into *retval the number of bytes in the resulting multibyte character sequence, not
including the terminating null character (if any).
-<p><!--para 17-->
+<p><!--para 17 -->
All elements following the terminating null character (if any) written by wcsrtombs_s
in the array of dstmax elements pointed to by dst take unspecified values when
wcsrtombs_s returns.<sup><a href="#note442"><b>442)</b></a></sup>
-<p><!--para 18-->
+<p><!--para 18 -->
If copying takes place between objects that overlap, the objects take on unspecified
values.
<h6>Returns</h6>
-<p><!--para 19-->
+<p><!--para 19 -->
The wcsrtombs_s function returns zero if no runtime-constraint violation and no
encoding error occurred. Otherwise, a nonzero value is returned.
-<!--page 666 indent 4-->
+<!--page 666 -->
<h6>footnotes</h6>
<p><small><a name="note441" href="#note441">441)</a> If conversion stops because a terminating null wide character has been reached, the bytes stored
Analyzability</pre>
<a name="L.1" href="#L.1"><h3>L.1 Scope</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
This annex specifies optional behavior that can aid in the analyzability of C programs.
-<p><!--para 2-->
+<p><!--para 2 -->
An implementation that defines __STDC_ANALYZABLE__ shall conform to the
specifications in this annex.<sup><a href="#note443"><b>443)</b></a></sup>
<a name="L.2" href="#L.2"><h3>L.2 Definitions</h3></a>
<a name="L.2.1" href="#L.2.1"><h4>L.2.1</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
out-of-bounds store
an (attempted) access (<a href="#3.1">3.1</a>) that, at run time, for a given computational state, would
modify (or, for an object declared volatile, fetch) one or more bytes that lie outside
the bounds permitted by this Standard.
<a name="L.2.2" href="#L.2.2"><h4>L.2.2</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
bounded undefined behavior
undefined behavior (<a href="#3.4.3">3.4.3</a>) that does not perform an out-of-bounds store.
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE 1 The behavior might perform a trap.
-<p><!--para 3-->
+<p><!--para 3 -->
NOTE 2 Any values produced or stored might be indeterminate values.
<a name="L.2.3" href="#L.2.3"><h4>L.2.3</h4></a>
-<p><!--para 1-->
+<p><!--para 1 -->
critical undefined behavior
undefined behavior that is not bounded undefined behavior.
-<p><!--para 2-->
+<p><!--para 2 -->
NOTE The behavior might perform an out-of-bounds store or perform a trap.
-<!--page 667 indent 4-->
+<!--page 667 -->
<a name="L.3" href="#L.3"><h3>L.3 Requirements</h3></a>
-<p><!--para 1-->
+<p><!--para 1 -->
If the program performs a trap (<a href="#3.19.5">3.19.5</a>), the implementation is permitted to invoke a
runtime-constraint handler. Any such semantics are implementation-defined.
-<p><!--para 2-->
+<p><!--para 2 -->
All undefined behavior shall be limited to bounded undefined behavior, except for the
following which are permitted to result in critical undefined behavior:
<ul>
function is used (<a href="#7.22.3">7.22.3</a>).
<li> A string or wide string utility function is instructed to access an array beyond the end
of an object (<a href="#7.23.1">7.23.1</a>, <a href="#7.28.4">7.28.4</a>).
-<!--page 668 indent -1-->
+<!--page 668 -->
</ul>
<a name="Bibliography" href="#Bibliography"><h2>Bibliography</h2></a>
<li> ISO/IEC 9899:1999/Cor.1:2001, Technical Corrigendum 1.
<li> ISO/IEC 9899:1999/Cor.2:2004, Technical Corrigendum 2.
<li> ISO/IEC 9899:1999/Cor.3:2007, Technical Corrigendum 3.
-<!--page 669 indent -1-->
+<!--page 669 -->
<li> ISO/IEC 9945-2:1993, Information technology -- Portable Operating System
Interface (POSIX) -- Part 2: Shell and Utilities.
<li> ISO/IEC TR 10176:1998, Information technology -- Guidelines for the
Cherokee.
<li> ISO/IEC 10967-1:1994, Information technology -- Language independent
arithmetic -- Part 1: Integer and floating point arithmetic.
-<!--page 670 indent -1-->
+<!--page 670 -->
<li> ISO/IEC TR 19769:2004, Information technology -- Programming languages,
their environments and system software interfaces -- Extensions for the
programming language C to support new character data types.
<li> ISO/IEC TR 24731-1:2007, Information technology -- Programming languages,
their environments and system software interfaces -- Extensions to the C library
-- Part 1: Bounds-checking interfaces.
-<!--page 671 indent 0-->
+<!--page 671 -->
</ol>
<a name="Index" href="#Index"><h2>Index</h2></a>
++ (postfix increment operator), <a href="#6.3.2.1">6.3.2.1</a>, <a href="#6.5.2.4">6.5.2.4</a> <a href="#7.18"><stdbool.h></a> header, <a href="#4">4</a>, <a href="#7.18">7.18</a>, <a href="#7.30.7">7.30.7</a>, <a href="#H">H</a>
++ (prefix increment operator), <a href="#6.3.2.1">6.3.2.1</a>, <a href="#6.5.3.1">6.5.3.1</a> <a href="#7.19"><stddef.h></a> header, <a href="#4">4</a>, <a href="#6.3.2.1">6.3.2.1</a>, <a href="#6.3.2.3">6.3.2.3</a>, <a href="#6.4.4.4">6.4.4.4</a>,
+= (addition assignment operator), <a href="#6.5.16.2">6.5.16.2</a>
-<!--page 672 indent 0-->
+<!--page 672 -->
<a href="#6.4.5">6.4.5</a>, <a href="#6.5.3.4">6.5.3.4</a>, <a href="#6.5.6">6.5.6</a>, <a href="#7.19">7.19</a>, <a href="#K.3.3">K.3.3</a> \x hexadecimal digits (hexadecimal-character
<a href="#7.20"><stdint.h></a> header, <a href="#4">4</a>, <a href="#5.2.4.2">5.2.4.2</a>, <a href="#6.10.1">6.10.1</a>, <a href="#7.8">7.8</a>, escape sequence), <a href="#6.4.4.4">6.4.4.4</a>
<a href="#7.20">7.20</a>, <a href="#7.30.8">7.30.8</a>, <a href="#K.3.3">K.3.3</a>, <a href="#K.3.4">K.3.4</a> ^ (bitwise exclusive OR operator), <a href="#6.2.6.2">6.2.6.2</a>, <a href="#6.5.11">6.5.11</a>
\u (universal character names), <a href="#6.4.3">6.4.3</a> _IONBF macro, <a href="#7.21.1">7.21.1</a>, <a href="#7.21.5.5">7.21.5.5</a>, <a href="#7.21.5.6">7.21.5.6</a>
\v (vertical-tab escape sequence), <a href="#5.2.2">5.2.2</a>, <a href="#6.4.4.4">6.4.4.4</a>, _Noreturn, <a href="#6.7.4">6.7.4</a>
<a href="#7.4.1.10">7.4.1.10</a> _Pragma operator, <a href="#5.1.1.2">5.1.1.2</a>, <a href="#6.10.9">6.10.9</a>
-<!--page 673 indent 0-->
+<!--page 673 -->
_Static_assert, <a href="#6.7.10">6.7.10</a>, <a href="#7.2">7.2</a> allocated storage, order and contiguity, <a href="#7.22.3">7.22.3</a>
_Thread_local storage-class specifier, <a href="#6.2.4">6.2.4</a>, and macro, <a href="#7.9">7.9</a>
<a href="#6.7.1">6.7.1</a> AND operators
structure/union member, <a href="#6.7.2.1">6.7.2.1</a> asin functions, <a href="#7.12.4.2">7.12.4.2</a>, <a href="#F.10.1.2">F.10.1.2</a>
alignment specifier, <a href="#6.7.5">6.7.5</a> asin type-generic macro, <a href="#7.24">7.24</a>, <a href="#G.7">G.7</a>
alignof operator, <a href="#6.5.3">6.5.3</a>, <a href="#6.5.3.4">6.5.3.4</a> asinh functions, <a href="#7.12.5.2">7.12.5.2</a>, <a href="#F.10.2.2">F.10.2.2</a>
-<!--page 674 indent 0-->
+<!--page 674 -->
asinh type-generic macro, <a href="#7.24">7.24</a>, <a href="#G.7">G.7</a> atomic_is_lock_free generic function,
asm keyword, <a href="#J.5.10">J.5.10</a> <a href="#7.17.5.1">7.17.5.1</a>
assert macro, <a href="#7.2.1.1">7.2.1.1</a> ATOMIC_LLONG_LOCK_FREE macro, <a href="#7.17.1">7.17.1</a>
<a href="#7.17.8.1">7.17.8.1</a> <a href="#6.8.2">6.8.2</a>
atomic_init generic function, <a href="#7.17.2.2">7.17.2.2</a> brackets operator ([ ]), <a href="#6.5.2.1">6.5.2.1</a>, <a href="#6.5.3.2">6.5.3.2</a>
ATOMIC_INT_LOCK_FREE macro, <a href="#7.17.1">7.17.1</a> brackets punctuator ([ ]), <a href="#6.7.6.2">6.7.6.2</a>, <a href="#6.7.9">6.7.9</a>
-<!--page 675 indent 0-->
+<!--page 675 -->
branch cuts, <a href="#7.3.3">7.3.3</a> type-generic macro for, <a href="#7.24">7.24</a>
break statement, <a href="#6.8.6.3">6.8.6.3</a> ccosh functions, <a href="#7.3.6.4">7.3.6.4</a>, <a href="#G.6.2.4">G.6.2.4</a>
broken-down time, <a href="#7.26.1">7.26.1</a>, <a href="#7.26.2.3">7.26.2.3</a>, <a href="#7.26.3">7.26.3</a>, type-generic macro for, <a href="#7.24">7.24</a>
cbrt functions, <a href="#7.12.7.1">7.12.7.1</a>, <a href="#F.10.4.1">F.10.4.1</a> clock_t type, <a href="#7.26.1">7.26.1</a>, <a href="#7.26.2.1">7.26.2.1</a>
cbrt type-generic macro, <a href="#7.24">7.24</a> CLOCKS_PER_SEC macro, <a href="#7.26.1">7.26.1</a>, <a href="#7.26.2.1">7.26.2.1</a>
ccos functions, <a href="#7.3.5.4">7.3.5.4</a>, <a href="#G.6">G.6</a> clog functions, <a href="#7.3.7.2">7.3.7.2</a>, <a href="#G.6.3.2">G.6.3.2</a>
-<!--page 676 indent 0-->
+<!--page 676 -->
type-generic macro for, <a href="#7.24">7.24</a> string, <a href="#7.23.3">7.23.3</a>, <a href="#K.3.7.2">K.3.7.2</a>
clog10 function, <a href="#7.30.1">7.30.1</a> wide string, <a href="#7.28.4.3">7.28.4.3</a>, <a href="#K.3.9.2.2">K.3.9.2.2</a>
clog1p function, <a href="#7.30.1">7.30.1</a> concatenation, preprocessing, see preprocessing
compound statement, <a href="#6.8.2">6.8.2</a> imaginary, <a href="#G.4.1">G.4.1</a>
compound-literal operator (( ){ }), <a href="#6.5.2.5">6.5.2.5</a> imaginary and complex, <a href="#G.4.3">G.4.3</a>
concatenation functions implicit, <a href="#6.3">6.3</a>
-<!--page 677 indent 0-->
+<!--page 677 -->
lvalues, <a href="#6.3.2.1">6.3.2.1</a> csinh functions, <a href="#7.3.6.5">7.3.6.5</a>, <a href="#G.6.2.5">G.6.2.5</a>
pointer, <a href="#6.3.2.1">6.3.2.1</a>, <a href="#6.3.2.3">6.3.2.3</a> type-generic macro for, <a href="#7.24">7.24</a>
real and complex, <a href="#6.3.1.7">6.3.1.7</a> csqrt functions, <a href="#7.3.8.3">7.3.8.3</a>, <a href="#G.6.4.2">G.6.4.2</a>
critical undefined behavior, <a href="#L.2.3">L.2.3</a> increment and decrement
csin functions, <a href="#7.3.5.5">7.3.5.5</a>, <a href="#G.6">G.6</a> default argument promotions, <a href="#6.5.2.2">6.5.2.2</a>
type-generic macro for, <a href="#7.24">7.24</a> default initialization, <a href="#6.7.9">6.7.9</a>
-<!--page 678 indent 0-->
+<!--page 678 -->
default label, <a href="#6.8.1">6.8.1</a>, <a href="#6.8.4.2">6.8.4.2</a> elif preprocessing directive, <a href="#6.10.1">6.10.1</a>
define preprocessing directive, <a href="#6.10.3">6.10.3</a> ellipsis punctuator (...), <a href="#6.5.2.2">6.5.2.2</a>, <a href="#6.7.6.3">6.7.6.3</a>, <a href="#6.10.3">6.10.3</a>
defined operator, <a href="#6.10.1">6.10.1</a>, <a href="#6.10.8">6.10.8</a> else preprocessing directive, <a href="#6.10.1">6.10.1</a>
<a href="#7.28.6.3.2">7.28.6.3.2</a>, <a href="#7.28.6.3.3">7.28.6.3.3</a>, <a href="#7.28.6.4.1">7.28.6.4.1</a>, <a href="#7.28.6.4.2">7.28.6.4.2</a>, ERANGE macro, <a href="#7.5">7.5</a>, <a href="#7.8.2.3">7.8.2.3</a>, <a href="#7.8.2.4">7.8.2.4</a>, <a href="#7.12.1">7.12.1</a>,
see also encoding error <a href="#7.22.1.3">7.22.1.3</a>, <a href="#7.22.1.4">7.22.1.4</a>, <a href="#7.28.4.1.1">7.28.4.1.1</a>, <a href="#7.28.4.1.2">7.28.4.1.2</a>, see
element type, <a href="#6.2.5">6.2.5</a> also range error, pole error
-<!--page 679 indent 0-->
+<!--page 679 -->
erf functions, <a href="#7.12.8.1">7.12.8.1</a>, <a href="#F.10.5.1">F.10.5.1</a> exp2 functions, <a href="#7.12.6.2">7.12.6.2</a>, <a href="#F.10.3.2">F.10.3.2</a>
erf type-generic macro, <a href="#7.24">7.24</a> exp2 type-generic macro, <a href="#7.24">7.24</a>
erfc functions, <a href="#7.12.8.2">7.12.8.2</a>, <a href="#F.10.5.2">F.10.5.2</a> explicit conversion, <a href="#6.3">6.3</a>
EXIT_SUCCESS macro, <a href="#7.22">7.22</a>, <a href="#7.22.4.4">7.22.4.4</a> FE_INEXACT macro, <a href="#7.6">7.6</a>, <a href="#F.3">F.3</a>
exp functions, <a href="#7.12.6.1">7.12.6.1</a>, <a href="#F.10.3.1">F.10.3.1</a> FE_INVALID macro, <a href="#7.6">7.6</a>, <a href="#7.12">7.12</a>, <a href="#F.3">F.3</a>
exp type-generic macro, <a href="#7.24">7.24</a> FE_OVERFLOW macro, <a href="#7.6">7.6</a>, <a href="#7.12">7.12</a>, <a href="#F.3">F.3</a>
-<!--page 680 indent 0-->
+<!--page 680 -->
FE_TONEAREST macro, <a href="#7.6">7.6</a>, <a href="#F.3">F.3</a> float _Complex type conversion, <a href="#6.3.1.6">6.3.1.6</a>,
FE_TOWARDZERO macro, <a href="#7.6">7.6</a>, <a href="#F.3">F.3</a> <a href="#6.3.1.7">6.3.1.7</a>, <a href="#6.3.1.8">6.3.1.8</a>
FE_UNDERFLOW macro, <a href="#7.6">7.6</a>, <a href="#F.3">F.3</a> float _Imaginary type, <a href="#G.2">G.2</a>
status flag fmin type-generic macro, <a href="#7.24">7.24</a>
flexible array member, <a href="#6.7.2.1">6.7.2.1</a> fmod functions, <a href="#7.12.10.1">7.12.10.1</a>, <a href="#F.10.7.1">F.10.7.1</a>
float _Complex type, <a href="#6.2.5">6.2.5</a> fmod type-generic macro, <a href="#7.24">7.24</a>
-<!--page 681 indent 0-->
+<!--page 681 -->
fopen function, <a href="#7.21.5.3">7.21.5.3</a>, <a href="#7.21.5.4">7.21.5.4</a>, <a href="#K.3.5.2.1">K.3.5.2.1</a> <a href="#K.3.5.3.7">K.3.5.3.7</a>, <a href="#K.3.5.3.9">K.3.5.3.9</a>
FOPEN_MAX macro, <a href="#7.21.1">7.21.1</a>, <a href="#7.21.3">7.21.3</a>, <a href="#7.21.4.3">7.21.4.3</a>, fseek function, <a href="#7.21.1">7.21.1</a>, <a href="#7.21.5.3">7.21.5.3</a>, <a href="#7.21.7.10">7.21.7.10</a>,
<a href="#K.3.5.1.1">K.3.5.1.1</a> <a href="#7.21.9.2">7.21.9.2</a>, <a href="#7.21.9.4">7.21.9.4</a>, <a href="#7.21.9.5">7.21.9.5</a>, <a href="#7.28.3.10">7.28.3.10</a>
fscanf function, <a href="#7.8.1">7.8.1</a>, <a href="#7.21.1">7.21.1</a>, <a href="#7.21.6.2">7.21.6.2</a>, fwscanf_s function, <a href="#K.3.9.1.2">K.3.9.1.2</a>, <a href="#K.3.9.1.5">K.3.9.1.5</a>,
<a href="#7.21.6.4">7.21.6.4</a>, <a href="#7.21.6.7">7.21.6.7</a>, <a href="#7.21.6.9">7.21.6.9</a>, <a href="#F.3">F.3</a>, <a href="#K.3.5.3.2">K.3.5.3.2</a> <a href="#K.3.9.1.7">K.3.9.1.7</a>, <a href="#K.3.9.1.14">K.3.9.1.14</a>
fscanf_s function, <a href="#K.3.5.3.2">K.3.5.3.2</a>, <a href="#K.3.5.3.4">K.3.5.3.4</a>,
-<!--page 682 indent 0-->
+<!--page 682 -->
gamma functions, <a href="#7.12.8">7.12.8</a>, <a href="#F.10.5">F.10.5</a> name spaces, <a href="#6.2.3">6.2.3</a>
general utilities, <a href="#7.22">7.22</a>, <a href="#K.3.6">K.3.6</a> reserved, <a href="#6.4.1">6.4.1</a>, <a href="#7.1.3">7.1.3</a>, <a href="#K.3.1.2">K.3.1.2</a>
wide string, <a href="#7.28.4">7.28.4</a>, <a href="#K.3.9.2">K.3.9.2</a> scope, <a href="#6.2.1">6.2.1</a>
identifier, <a href="#6.4.2.1">6.4.2.1</a>, <a href="#6.5.1">6.5.1</a> unsequenced
linkage, see linkage indirection operator (*), <a href="#6.5.2.1">6.5.2.1</a>, <a href="#6.5.3.2">6.5.3.2</a>
maximum length, <a href="#6.4.2.1">6.4.2.1</a> inequality operator (!=), <a href="#6.5.9">6.5.9</a>
-<!--page 683 indent 0-->
+<!--page 683 -->
infinitary, <a href="#7.12.1">7.12.1</a> extended, <a href="#6.2.5">6.2.5</a>, <a href="#6.3.1.1">6.3.1.1</a>, <a href="#6.4.4.1">6.4.4.1</a>, <a href="#7.20">7.20</a>
INFINITY macro, <a href="#7.3.9.5">7.3.9.5</a>, <a href="#7.12">7.12</a>, <a href="#F.2.1">F.2.1</a> inter-thread happens before, <a href="#5.1.2.4">5.1.2.4</a>
initial position, <a href="#5.2.2">5.2.2</a> interactive device, <a href="#5.1.2.3">5.1.2.3</a>, <a href="#7.21.3">7.21.3</a>, <a href="#7.21.5.3">7.21.5.3</a>
integer type conversion, <a href="#6.3.1.1">6.3.1.1</a>, <a href="#6.3.1.3">6.3.1.3</a>, <a href="#6.3.1.4">6.3.1.4</a>, ispunct function, <a href="#7.4.1.2">7.4.1.2</a>, <a href="#7.4.1.7">7.4.1.7</a>, <a href="#7.4.1.9">7.4.1.9</a>,
<a href="#F.3">F.3</a>, <a href="#F.4">F.4</a> <a href="#7.4.1.11">7.4.1.11</a>
integer types, <a href="#6.2.5">6.2.5</a>, <a href="#7.20">7.20</a> isspace function, <a href="#7.4.1.2">7.4.1.2</a>, <a href="#7.4.1.7">7.4.1.7</a>, <a href="#7.4.1.9">7.4.1.9</a>,
-<!--page 684 indent 0-->
+<!--page 684 -->
<a href="#7.4.1.10">7.4.1.10</a>, <a href="#7.4.1.11">7.4.1.11</a>, <a href="#7.21.6.2">7.21.6.2</a>, <a href="#7.22.1.3">7.22.1.3</a>, LC_ALL macro, <a href="#7.11">7.11</a>, <a href="#7.11.1.1">7.11.1.1</a>, <a href="#7.11.2.1">7.11.2.1</a>
<a href="#7.22.1.4">7.22.1.4</a>, <a href="#7.28.2.2">7.28.2.2</a> LC_COLLATE macro, <a href="#7.11">7.11</a>, <a href="#7.11.1.1">7.11.1.1</a>, <a href="#7.23.4.3">7.23.4.3</a>,
isunordered macro, <a href="#7.12.14.6">7.12.14.6</a>, <a href="#F.3">F.3</a> <a href="#7.28.4.4.2">7.28.4.4.2</a>
future directions, <a href="#6.11">6.11</a> use of functions, <a href="#7.1.4">7.1.4</a>
syntax summary, <a href="#A">A</a> lifetime, <a href="#6.2.4">6.2.4</a>
Latin alphabet, <a href="#5.2.1">5.2.1</a>, <a href="#6.4.2.1">6.4.2.1</a> limits
-<!--page 685 indent 0-->
+<!--page 685 -->
environmental, see environmental limits <a href="#6.3.1.6">6.3.1.6</a>, <a href="#6.3.1.7">6.3.1.7</a>, <a href="#6.3.1.8">6.3.1.8</a>
implementation, see implementation limits long double _Imaginary type, <a href="#G.2">G.2</a>
numerical, see numerical limits long double suffix, l or <a href="#L">L</a>, <a href="#6.4.4.2">6.4.4.2</a>
logical source lines, <a href="#5.1.1.2">5.1.1.2</a> malloc function, <a href="#7.22.3">7.22.3</a>, <a href="#7.22.3.4">7.22.3.4</a>, <a href="#7.22.3.5">7.22.3.5</a>
long double _Complex type, <a href="#6.2.5">6.2.5</a> manipulation functions
long double _Complex type conversion, complex, <a href="#7.3.9">7.3.9</a>
-<!--page 686 indent 0-->
+<!--page 686 -->
real, <a href="#7.12.11">7.12.11</a>, <a href="#F.10.8">F.10.8</a> modf functions, <a href="#7.12.6.12">7.12.6.12</a>, <a href="#F.10.3.12">F.10.3.12</a>
matching failure, <a href="#7.28.2.6">7.28.2.6</a>, <a href="#7.28.2.8">7.28.2.8</a>, <a href="#7.28.2.10">7.28.2.10</a>, modifiable lvalue, <a href="#6.3.2.1">6.3.2.1</a>
<a href="#K.3.9.1.7">K.3.9.1.7</a>, <a href="#K.3.9.1.10">K.3.9.1.10</a>, <a href="#K.3.9.1.12">K.3.9.1.12</a> modification order, <a href="#5.1.2.4">5.1.2.4</a>
string, <a href="#7.23.6">7.23.6</a>, <a href="#K.3.7.4">K.3.7.4</a> nearbyint functions, <a href="#7.12.9.3">7.12.9.3</a>, <a href="#7.12.9.4">7.12.9.4</a>, <a href="#F.3">F.3</a>,
wide string, <a href="#7.28.4.6">7.28.4.6</a>, <a href="#K.3.9.2.4">K.3.9.2.4</a> <a href="#F.10.6.3">F.10.6.3</a>
mktime function, <a href="#7.26.2.3">7.26.2.3</a> nearbyint type-generic macro, <a href="#7.24">7.24</a>
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nearest integer functions, <a href="#7.12.9">7.12.9</a>, <a href="#F.10.6">F.10.6</a> operating system, <a href="#5.1.2.1">5.1.2.1</a>, <a href="#7.22.4.8">7.22.4.8</a>
negation operator (!), <a href="#6.5.3.3">6.5.3.3</a> operations on files, <a href="#7.21.4">7.21.4</a>, <a href="#K.3.5.1">K.3.5.1</a>
negative zero, <a href="#6.2.6.2">6.2.6.2</a>, <a href="#7.12.11.1">7.12.11.1</a> operator, <a href="#6.4.6">6.4.6</a>
ONCE_FLAG_INIT macro, <a href="#7.25.1">7.25.1</a> parentheses punctuator (( )), <a href="#6.7.6.3">6.7.6.3</a>, <a href="#6.8.4">6.8.4</a>, <a href="#6.8.5">6.8.5</a>
ones' complement, <a href="#6.2.6.2">6.2.6.2</a> parenthesized expression, <a href="#6.5.1">6.5.1</a>
operand, <a href="#6.4.6">6.4.6</a>, <a href="#6.5">6.5</a> parse state, <a href="#7.21.2">7.21.2</a>
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perform a trap, <a href="#3.19.5">3.19.5</a> preprocessor, <a href="#6.10">6.10</a>
permitted form of initializer, <a href="#6.6">6.6</a> PRIcFASTN macros, <a href="#7.8.1">7.8.1</a>
perror function, <a href="#7.21.10.4">7.21.10.4</a> PRIcLEASTN macros, <a href="#7.8.1">7.8.1</a>
defined, <a href="#6.10.1">6.10.1</a>
preprocessing tokens, <a href="#5.1.1.2">5.1.1.2</a>, <a href="#6.4">6.4</a>, <a href="#6.10">6.10</a> raise function, <a href="#7.14">7.14</a>, <a href="#7.14.1.1">7.14.1.1</a>, <a href="#7.14.2.1">7.14.2.1</a>, <a href="#7.22.4.1">7.22.4.1</a>
preprocessing translation unit, <a href="#5.1.1.1">5.1.1.1</a> rand function, <a href="#7.22">7.22</a>, <a href="#7.22.2.1">7.22.2.1</a>, <a href="#7.22.2.2">7.22.2.2</a>
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RAND_MAX macro, <a href="#7.22">7.22</a>, <a href="#7.22.2.1">7.22.2.1</a> restrict-qualified type, <a href="#6.2.5">6.2.5</a>, <a href="#6.7.3">6.7.3</a>
range return statement, <a href="#6.8.6.4">6.8.6.4</a>, <a href="#F.6">F.6</a>
excess, <a href="#5.2.4.2.2">5.2.4.2.2</a>, <a href="#6.3.1.8">6.3.1.8</a>, <a href="#6.8.6.4">6.8.6.4</a> rewind function, <a href="#7.21.5.3">7.21.5.3</a>, <a href="#7.21.7.10">7.21.7.10</a>, <a href="#7.21.9.5">7.21.9.5</a>,
functions, <a href="#7.28.6.4">7.28.6.4</a>, <a href="#K.3.9.3.2">K.3.9.3.2</a> string, <a href="#7.23.5">7.23.5</a>, <a href="#K.3.7.3">K.3.7.3</a>
restore calling environment function, <a href="#7.13.2">7.13.2</a> utility, <a href="#7.22.5">7.22.5</a>, <a href="#K.3.6.3">K.3.6.3</a>
restrict type qualifier, <a href="#6.7.3">6.7.3</a>, <a href="#6.7.3.1">6.7.3.1</a> wide string, <a href="#7.28.4.5">7.28.4.5</a>, <a href="#K.3.9.2.3">K.3.9.2.3</a>
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SEEK_CUR macro, <a href="#7.21.1">7.21.1</a>, <a href="#7.21.9.2">7.21.9.2</a> sign and magnitude, <a href="#6.2.6.2">6.2.6.2</a>
SEEK_END macro, <a href="#7.21.1">7.21.1</a>, <a href="#7.21.9.2">7.21.9.2</a> sign bit, <a href="#6.2.6.2">6.2.6.2</a>
SEEK_SET macro, <a href="#7.21.1">7.21.1</a>, <a href="#7.21.9.2">7.21.9.2</a> signal function, <a href="#7.14.1.1">7.14.1.1</a>, <a href="#7.22.4.5">7.22.4.5</a>, <a href="#7.22.4.7">7.22.4.7</a>
SIGFPE macro, <a href="#7.12.1">7.12.1</a>, <a href="#7.14">7.14</a>, <a href="#7.14.1.1">7.14.1.1</a>, <a href="#J.5.17">J.5.17</a> <a href="#7.4.1.10">7.4.1.10</a>, <a href="#7.29.2.1.3">7.29.2.1.3</a>
SIGILL macro, <a href="#7.14">7.14</a>, <a href="#7.14.1.1">7.14.1.1</a> sprintf function, <a href="#7.21.6.6">7.21.6.6</a>, <a href="#7.21.6.13">7.21.6.13</a>, <a href="#K.3.5.3.6">K.3.5.3.6</a>
SIGINT macro, <a href="#7.14">7.14</a> sprintf_s function, <a href="#K.3.5.3.5">K.3.5.3.5</a>, <a href="#K.3.5.3.6">K.3.5.3.6</a>
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sqrt functions, <a href="#7.12.7.5">7.12.7.5</a>, <a href="#F.3">F.3</a>, <a href="#F.10.4.5">F.10.4.5</a> do, <a href="#6.8.5.2">6.8.5.2</a>
sqrt type-generic macro, <a href="#7.24">7.24</a> else, <a href="#6.8.4.1">6.8.4.1</a>
srand function, <a href="#7.22.2.2">7.22.2.2</a> expression, <a href="#6.8.3">6.8.3</a>
break, <a href="#6.8.6.3">6.8.6.3</a> strcpy function, <a href="#7.23.2.3">7.23.2.3</a>
compound, <a href="#6.8.2">6.8.2</a> strcpy_s function, <a href="#K.3.7.1.3">K.3.7.1.3</a>
continue, <a href="#6.8.6.2">6.8.6.2</a> strcspn function, <a href="#7.23.5.3">7.23.5.3</a>
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streams, <a href="#7.21.2">7.21.2</a>, <a href="#7.22.4.4">7.22.4.4</a> <a href="#7.22.1.4">7.22.1.4</a>, <a href="#7.28.2.2">7.28.2.2</a>
fully buffered, <a href="#7.21.3">7.21.3</a> strtoull function, <a href="#7.8.2.3">7.8.2.3</a>, <a href="#7.22.1.2">7.22.1.2</a>, <a href="#7.22.1.4">7.22.1.4</a>
line buffered, <a href="#7.21.3">7.21.3</a> strtoumax function, <a href="#7.8.2.3">7.8.2.3</a>
strtold function, <a href="#7.12.11.2">7.12.11.2</a>, <a href="#7.22.1.3">7.22.1.3</a>, <a href="#F.3">F.3</a> tan functions, <a href="#7.12.4.7">7.12.4.7</a>, <a href="#F.10.1.7">F.10.1.7</a>
strtoll function, <a href="#7.8.2.3">7.8.2.3</a>, <a href="#7.22.1.2">7.22.1.2</a>, <a href="#7.22.1.4">7.22.1.4</a> tan type-generic macro, <a href="#7.24">7.24</a>, <a href="#G.7">G.7</a>
strtoul function, <a href="#7.8.2.3">7.8.2.3</a>, <a href="#7.21.6.2">7.21.6.2</a>, <a href="#7.22.1.2">7.22.1.2</a>, tanh functions, <a href="#7.12.5.6">7.12.5.6</a>, <a href="#F.10.2.6">F.10.2.6</a>
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tanh type-generic macro, <a href="#7.24">7.24</a>, <a href="#G.7">G.7</a> toupper function, <a href="#7.4.2.2">7.4.2.2</a>
temporary lifetime, <a href="#6.2.4">6.2.4</a> towctrans function, <a href="#7.29.3.2.1">7.29.3.2.1</a>, <a href="#7.29.3.2.2">7.29.3.2.2</a>
tentative definition, <a href="#6.9.2">6.9.2</a> towlower function, <a href="#7.29.3.1.1">7.29.3.1.1</a>, <a href="#7.29.3.2.1">7.29.3.2.1</a>
token concatenation, <a href="#6.10.3.3">6.10.3.3</a> imaginary, <a href="#G">G</a>
token pasting, <a href="#6.10.3.3">6.10.3.3</a> restrict qualified, <a href="#6.7.3">6.7.3</a>
tolower function, <a href="#7.4.2.1">7.4.2.1</a> volatile qualified, <a href="#6.7.3">6.7.3</a>
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uchar.h header, <a href="#6.4.4.4">6.4.4.4</a>, <a href="#6.4.5">6.4.5</a>, <a href="#7.27">7.27</a> universal character name, <a href="#6.4.3">6.4.3</a>
UCHAR_MAX macro, <a href="#5.2.4.2.1">5.2.4.2.1</a> unnormalized floating-point numbers, <a href="#5.2.4.2.2">5.2.4.2.2</a>
UINT_FASTN_MAX macros, <a href="#7.20.2.3">7.20.2.3</a> unqualified type, <a href="#6.2.5">6.2.5</a>
specifier, <a href="#6.7.2.1">6.7.2.1</a> <a href="#K.3.9.1.10">K.3.9.1.10</a>, <a href="#K.3.9.1.12">K.3.9.1.12</a>
tag, <a href="#6.2.3">6.2.3</a>, <a href="#6.7.2.3">6.7.2.3</a> value, <a href="#3.19">3.19</a>
type, <a href="#6.2.5">6.2.5</a>, <a href="#6.7.2.1">6.7.2.1</a> value bits, <a href="#6.2.6.2">6.2.6.2</a>
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variable arguments, <a href="#6.10.3">6.10.3</a>, <a href="#7.16">7.16</a> vswscanf function, <a href="#7.28.2.8">7.28.2.8</a>
variable arguments header, <a href="#7.16">7.16</a> vswscanf_s function, <a href="#K.3.9.1.10">K.3.9.1.10</a>
variable length array, <a href="#6.7.6">6.7.6</a>, <a href="#6.7.6.2">6.7.6.2</a>, <a href="#6.10.8.3">6.10.8.3</a> vwprintf function, <a href="#7.21.1">7.21.1</a>, <a href="#7.28.2.9">7.28.2.9</a>, <a href="#K.3.9.1.11">K.3.9.1.11</a>
vswprintf function, <a href="#7.28.2.7">7.28.2.7</a>, <a href="#K.3.9.1.8">K.3.9.1.8</a>, <a href="#7.28.4.1.2">7.28.4.1.2</a>
<a href="#K.3.9.1.9">K.3.9.1.9</a> wcstold function, <a href="#7.28.4.1.1">7.28.4.1.1</a>
vswprintf_s function, <a href="#K.3.9.1.8">K.3.9.1.8</a>, <a href="#K.3.9.1.9">K.3.9.1.9</a> wcstoll function, <a href="#7.8.2.4">7.8.2.4</a>, <a href="#7.28.4.1.2">7.28.4.1.2</a>
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wcstombs function, <a href="#7.22.8.2">7.22.8.2</a>, <a href="#7.28.6.4">7.28.6.4</a> <a href="#7.29.1">7.29.1</a>
wcstombs_s function, <a href="#K.3.6.5.2">K.3.6.5.2</a> wmemchr function, <a href="#7.28.4.5.8">7.28.4.5.8</a>
wcstoul function, <a href="#7.8.2.4">7.8.2.4</a>, <a href="#7.21.6.2">7.21.6.2</a>, <a href="#7.28.2.2">7.28.2.2</a>, wmemcmp function, <a href="#7.28.4.4.5">7.28.4.4.5</a>
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