stddef.h

<stddef.h>(P)							<stddef.h>(P)



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 mem-
	      ber 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
       utility.

       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 Technol-
       ogy -- 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 .



POSIX				     2003			<stddef.h>(P)