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Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!hp4nl!orcenl!bengsig
From: bengsig@dk.oracle.com (Bjorn Engsig)
Newsgroups: comp.lang.c,comp.std.c
Subject: Re: Need macro to get offset within a structure
Message-ID: <1263@dkunix9.dk.oracle.com>
Date: 21 Feb 91 12:36:41 GMT
References: <1991Feb16.232713.6001@runx.oz.au> <ENAG.91Feb19131201@holmenkollen.ifi.uio.no>
Reply-To: bengsig@dk.oracle.com (Bjorn Engsig)
Followup-To: comp.std.c
Organization: Oracle Denmark
Lines: 17

In article <1991Feb16.232713.6001@runx.oz.au>, Richard Murnane writes:
|Does anybody know a decent macro to find the offset of an element
|in a structure

And in article <ENAG.91Feb19131201@holmenkollen.ifi.uio.no> enag@ifi.uio.no
(Erik Naggum) replied:
|#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
|This works like a charm on a vast number of compilers I've used.

Actually, ANSI C includes an offsetof macro in <stddef.h>.  And please do
not enter the usual discussion of wheather the macro definition above is
valid ANSI C or not.  The rationale of the ANSI C will fill you in with the
details of this.
-- 
Bjorn Engsig, ORACLE Corporation, E-mail: bengsig@oracle.com, bengsig@oracle.nl

            "Stepping in others footsteps, doesn't bring you ahead"