<stddef.h>(P) POSIX Programmer's Manual <stddef.h>(P)
stddef.h - standard type definitions
The <stddef.h> header shall define the following macros:
NULL Null pointer constant.
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 struc-
The <stddef.h> header shall define the following types:
Signed integer type of the result of subtracting two pointers.
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 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 environments can be obtained using the confstr() function or the get-
The following sections are informative.
<wchar.h> , <sys/types.h> , the System Interfaces volume of IEEE Std 1003.1-2001, conf-
str(), the Shell and Utilities volume of IEEE Std 1003.1-2001, getconf
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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 <stddef.h>(P)