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From: jc@minya.UUCP (John Chambers)
Newsgroups: comp.lang.c,comp.unix.wizards
Subject: Re: pointer alignment when int != char *
Message-ID: <129@minya.UUCP>
Date: Fri, 28-Aug-87 23:34:53 EDT
Article-I.D.: minya.129
Posted: Fri Aug 28 23:34:53 1987
Date-Received: Sun, 30-Aug-87 07:27:08 EDT
References: <493@its63b.ed.ac.uk> <6061@brl-smoke.ARPA> <3812@spool.WISC.EDU> <483@mtxinu.UUCP>
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Xref: mnetor comp.lang.c:4015 comp.unix.wizards:3965

In article <483@mtxinu.UUCP>, ed@mtxinu.UUCP (Ed Gould) writes:
> ># To subtract two independent large-model pointers of the type
> ># segment:offset, I tried this:
> ># 
> >#      (unsigned long) p2 - (unsigned long) p1
> ># 
> >
> >This is bad practice.
> 
> It's also not legal in the proposed ANSI C standard.  Pointers
> may be subtracted *only* if they point to members of the same
> array of elements.  

Huh?  This example isn't subtracting pointers to anything.  It is 
subtracting two unsigned longs.  I sure hope that's defined.

I also hope that the ANSI standards haven't done THAT much damage
to C semantics!

(:-)








-- 
	John Chambers <{adelie,ima,maynard}!minya!{jc,root}> (617/484-6393)