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

NAME
       stddef.h - standard type definitions
SYNOPSIS
       #include <stddef.h>
DESCRIPTION
       The <stddef.h> header shall define the following macros:
       NULL   Null pointer constant.
       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-designa-
              tor), 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 wide-
              character codes for all members of  the  largest  character  set
              specified  among  the locales supported by the compilation envi-
              ronment: the null character has the code value 0 and each member
              of  the  portable  character  set  has a code value equal to its
              value when used as the lone character in  an  integer  character
              constant.
       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 environ-
       ments can be obtained using the confstr() function or the getconf util-
       ity.
       The following sections are informative.
APPLICATION USAGE
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       <wchar.h>,    <sys/types.h>,    the   System   Interfaces   volume   of
       IEEE Std 1003.1-2001, confstr(), the  Shell  and  Utilities  volume  of
       IEEE Std 1003.1-2001, getconf
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                       <stddef.h>(0P)