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From: chris@mimsy.UUCP
Newsgroups: comp.lang.c
Subject: Re: char (*a)[]  (was: Style [++i vs i++])
Message-ID: <8655@mimsy.UUCP>
Date: Sat, 19-Sep-87 18:50:26 EDT
Article-I.D.: mimsy.8655
Posted: Sat Sep 19 18:50:26 1987
Date-Received: Sun, 20-Sep-87 16:22:35 EDT
References: <8298@brl-adm.ARPA> <587@cblpe.ATT.COM> <189@xyzzy.UUCP> <2474@xanth.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 29
Keywords: brain dead architectures versus X3J11

>>	for( p = &foo[9]; p >= foo; --p ){	/* loops forever */

In article <2474@xanth.UUCP> kent@xanth.UUCP (Kent Paul Dolan) writes:
>I love it!
>
>OK, X3J11, the ball's in your court.  Do we teach every C programmer
>on every architecture in the world that decrementing pointer loops are
>a no-no, and break half the code in existance, or do we finally bite
>the bullet and decide that compiler writers for brain dead
>architectures, and not the whole C community, pay the penalty for bad
>hardware designs?  Especially since these folks are often the
>perpetrators of the bad hardware design.

Unfortunately for you, it has already been considered, and the
answer is that

	for (p = foo; p < &foo[10]; p++)

is portable, and compilers must allow for it, but

	for (p = &foo[9]; p >= foo; p--)

is not, and compilers need not allow for it.  This does not `break
half the code in existence' except when one tries to run it on an
architecture in which &foo[-1] >= &foo[0] (where---surprise!---it
already fails).
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris