Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!wuarchive!hsdndev!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: finding offset of a member in C structures
Message-ID: <16220@smoke.brl.mil>
Date: 22 May 91 00:45:09 GMT
References: <1991May20.212338.24349@thyme.jpl.nasa.gov> <16211@smoke.brl.mil> <22051@paperboy.OSF.ORG>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 12

In article <22051@paperboy.OSF.ORG> dbrooks@osf.org (David Brooks) writes:
>The method you posted:
>	struct a_struct foo;
>	int offset2 = (char *)&foo.member2 - (char *)&foo; /* for example */
>has an unfortunate drawback.  You need to be able to declare foo, and
>squander space for it.  The ubiquitous uses in X don't have those luxuries.

No, you don't.  If you understood my example, you should be able to apply
the technique whenever you can latch onto, for example, a pointer to a
struct of the appropriate type.

The X11 source code style is ATROCIOUS and should not be used as a model.