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From: meissner@xyzzy.UUCP (Michael Meissner)
Newsgroups: comp.lang.c,comp.unix.wizards
Subject: Re: pointer alignment when int != char *
Message-ID: <179@xyzzy.UUCP>
Date: Wed, 31-Dec-69 18:59:59 EDT
Article-I.D.: xyzzy.179
Posted: Wed Dec 31 18:59:59 1969
Date-Received: Sat, 8-Aug-87 11:47:19 EDT
References: <493@its63b.ed.ac.uk> <6061@brl-smoke.ARPA> <3812@spool.WISC.EDU> <688@haddock.UUCP> <13218@topaz.rutgers.edu> <161@xyzzy.UUCP> <13676@topaz.rutgers.edu>
Reply-To: meissner@nightmare.UUCP (Michael Meissner)
Organization: Data General (Languages @ Research Triangle Park, NC.)
Lines: 14
Xref: mnetor comp.lang.c:3506 comp.unix.wizards:3585

In article <13676@topaz.rutgers.edu> ron@topaz.rutgers.edu (Ron Natalie) writes:
> More correctly stated that if your the difference between two pointers is
> ever more than that that can be represented by a long, you are in trouble.
> 
> -Ron

Actually, to be more precise, if the difference between two pointers which
point to members of the SAME array is ever more than that which can be
represented by a long, you are in trouble.  All of the standards say that
pointer subtraction is only defined within an aggregate.  This allows putting
each top level item into a separate segment on say an 80*86, and only doing
the subtraction between the two offsets.  Many MSDOS compilers do this
already.
-- 
Michael Meissner, Data General.		Uucp: ...!mcnc!rti!xyzzy!meissner