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From: pmk@craycos.com (Peter Klausler)
Newsgroups: comp.lang.c
Subject: Re: How to get a byte offset
Message-ID: <1990May28.163515.7070@craycos.com>
Date: 28 May 90 16:35:15 GMT
Organization: Cray Computer Corporation
Lines: 10

>Is there an easy way to get the byte offset of a field in a structure without
>counting it manually ?

In ANS C, #include <stddef.h> and use the offsetof macro.

If you don't have access to a standard compiler, try this common trick:

#define offsetof(type,member)	((char *) &((type *) 0)->member - (char *) 0)

-Peter Klausler, a compiler guy at Cray Computer Corp. in Colorado Springs