Xref: utzoo comp.lang.c:14121 comp.lang.c++:1996
Path: utzoo!attcan!uunet!husc6!mailrus!ames!amdcad!weitek!sci!auspyr!mick
From: mick@auspyr.UUCP (Michael J. Andrew)
Newsgroups: comp.lang.c,comp.lang.c++
Subject: Re: Something new for C?
Keywords: offset of vars within structures
Message-ID: <13414@auspyr.UUCP>
Date: 15 Nov 88 01:31:16 GMT
References: <73@dsoft.UUCP>
Reply-To: mick@auspyr.UUCP (Michael J. Andrew)
Organization: Austec Inc., San Jose, Ca, USA
Lines: 23

In article <73@dsoft.UUCP> root@dsoft.UUCP (Super user) writes:
|Maybe I've missed something in C, but One of the things I've never found a way
|to do and have always wanted, was a precompiler command to allow me to use
|the offset of an item into a structure. for example:
|
|struct test {
|   long this;
|   int  that;
|   char those[8];
|};
|
|   val = offset(test,that);

Try the following:

#define OFFSET(structure,field)  ((int) &(((struct structure *)0)->field))

A useful trick which I'm afraid I cannot take credit for. Watch out for
hardware with brain damaged (read "clever") addressing!
-- 
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Michael Andrew        Sr. Systems Engineer    Austec, Inc.  San Jose CA.
mick@auspyr.UUCP  or amdahl!auspyr!mick       (408) 279 5533