Sun Microsystems, Inc. gratefully acknowledges The Open Group for
permission to reproduce portions of its copyrighted documentation.
Original documentation from The Open Group can be obtained online at

The Institute of Electrical and Electronics Engineers and The Open
Group, have given us permission to reprint portions of their

In the following statement, the phrase ``this text'' refers to portions
of the system documentation.

Portions of this text are reprinted and reproduced in electronic form
in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6,
Copyright (C) 2001-2004 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy
between these versions 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

This notice shall appear on any product containing this material.

The contents of this file are subject to the terms of the
Common Development and Distribution License (the "License").
You may not use this file except in compliance with the License.

You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
See the License for the specific language governing permissions
and limitations under the License.

When distributing Covered Code, include this CDDL HEADER in each
file and include the License file at usr/src/OPENSOLARIS.LICENSE.
If applicable, add the following below this CDDL HEADER, with the
fields enclosed by brackets "[]" replaced with your own identifying
information: Portions Copyright [yyyy] [name of copyright owner]

Copyright (c) 2001, The IEEE and The Open Group. All Rights Reserved.
Portions Copyright (c) 2004, Sun Microsystems, Inc. All Rights Reserved.
Copyright 2016, Joyent, Inc.

STDDEF.H 3HEAD "Jan 14, 2015"
stddef.h, stddef - standard type definitions

#include <stddef.h>

The <stddef.h> header defines 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 defines the following types: ptrdiff_t

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 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.


Unsigned integer type of the result of the sizeof operator.


A type that represents the maximum alignment supported by the platform. The type may or may not be an integer type, it may or may not be signed, no assumptions should be made, other than that it has the maximum fundamental alignment of the platform.

The implementation supports 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(3C) function or the getconf(1) utility.


See attributes(7) for descriptions of the following attributes:

Interface Stability Standard

getconf (1), confstr (3C), types.h (3HEAD), wchar.h (3HEAD), attributes (7), standards (7)