PROLOG | NAME | SYNOPSIS | DESCRIPTION | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

stddef.h(0P)              POSIX Programmer's Manual             stddef.h(0P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       stddef.h — standard type definitions

SYNOPSIS         top

       #include <stddef.h>

DESCRIPTION         top

       The functionality described on this reference page is aligned with
       the ISO C standard. Any conflict between the requirements described
       here and the ISO C standard is unintentional. This volume of
       POSIX.1‐2008 defers to the ISO C standard.

       The <stddef.h> header shall define the following macros:

       NULL      Null pointer constant.  The macro shall expand to an
                 integer constant expression with the value 0 cast to type
                 void *.

       offsetof(type, member-designator)
                 Integer constant expression of type size_t, the value of
                 which is the offset in bytes to the structure member
                 (member-designator), from the beginning of its structure
                 (type).

       The <stddef.h> header shall define the following types:

       ptrdiff_t Signed integer type of the result of subtracting two
                 pointers.

       wchar_t   Integer type whose range of values can represent distinct
                 codes for all members of the largest extended character set
                 specified among the supported locales; the null character
                 shall have the code value zero. Each member of the basic
                 character set 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__.

       size_t    Unsigned integer type of the result of the sizeof operator.

       The implementation shall support one or more programming environments
       in which the widths of ptrdiff_t, size_t, and wchar_t are no greater
       than the width of type long.  The names of these programming
       environments can be obtained using the confstr() function or the
       getconf utility.

       The following sections are informative.

APPLICATION USAGE         top

       None.

RATIONALE         top

       The ISO C standard does not require the NULL macro to include the
       cast to type void * and specifies that the NULL macro be
       implementation-defined. POSIX.1‐2008 requires the cast and therefore
       need not be implementation-defined.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       sys_types.h(0p), wchar.h(0p)

       The System Interfaces volume of POSIX.1‐2008, confstr(3p)

       The Shell and Utilities volume of POSIX.1‐2008, getconf(1p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) In the event of any discrepancy between this version and
       the original IEEE and The Open Group Standard, the original IEEE and
       The Open Group Standard is the referee document. The original
       Standard can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                        stddef.h(0P)