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-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 wide-character codes for
              all members of the largest character set specified among the locales  supported  by
              the  compilation  environment:  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  environments  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 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 .