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

6       stddef.h - standard type definitions
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SYNOPSIS

9       #include <stddef.h>
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DESCRIPTION

12       The <stddef.h> header shall define the following macros:
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14       NULL   Null pointer constant.
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16       offsetof(type, member-designator)
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18              Integer  constant  expression of type size_t, the value of which
19              is the offset in bytes to the structure member  (member-designa‐
20              tor), from the beginning of its structure (type).
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23       The <stddef.h> header shall define the following types:
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25       ptrdiff_t
26              Signed integer type of the result of subtracting two pointers.
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28       wchar_t
29              Integer  type whose range of values can represent distinct wide-
30              character codes for all members of  the  largest  character  set
31              specified  among  the locales supported by the compilation envi‐
32              ronment: the null character has the code value 0 and each member
33              of  the  portable  character  set  has a code value equal to its
34              value when used as the lone character in  an  integer  character
35              constant.
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37       size_t Unsigned integer type of the result of the sizeof operator.
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40       The  implementation  shall support one or more programming environments
41       in which the widths of ptrdiff_t, size_t, and wchar_t  are  no  greater
42       than  the  width of type long.  The names of these programming environ‐
43       ments can be obtained using the confstr() function or the getconf util‐
44       ity.
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46       The following sections are informative.
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APPLICATION USAGE

49       None.
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RATIONALE

52       None.
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FUTURE DIRECTIONS

55       None.
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SEE ALSO

58       <wchar.h>,    <sys/types.h>,    the   System   Interfaces   volume   of
59       IEEE Std 1003.1-2001, confstr(), the  Shell  and  Utilities  volume  of
60       IEEE Std 1003.1-2001, getconf
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63       Portions  of  this text are reprinted and reproduced in electronic form
64       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
65       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
66       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
67       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
68       event of any discrepancy between this version and the original IEEE and
69       The  Open Group Standard, the original IEEE and The Open Group Standard
70       is the referee document. The original Standard can be  obtained  online
71       at http://www.opengroup.org/unix/online.html .
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75IEEE/The Open Group                  2003                       <stddef.h>(0P)
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