Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: how about sizeof(((type *)1)->member) ?
Message-ID: <11440@smoke.BRL.MIL>
Date: 30 Oct 89 13:37:07 GMT
References: <1989Oct27.141015.20578@talos.uucp> <2550111@hpisod2.HP.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 12

In article <2550111@hpisod2.HP.COM> decot@hpisod2.HP.COM (Dave Decot) writes:
>OK, fine.  My what a tiresome language.  Here:
>    sizeof(((struct foo *)(sizeof(struct foo)))->member)

The constraint is not imposed by the language, but rather by the
available computer architectures.  Since C permits the programmer
to get "close" to the architecture, these warts become more
visible than in some higher-level languages.

The reason offsetof() is specified as part of a conforming
implementation in the C Standard is to keep programmers from
trying to concoct their own non-portable invention for this.