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From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: Auto variable with sizeof == 0
Message-ID: <5258@mimsy.UUCP>
Date: Sun, 1-Feb-87 20:53:48 EST
Article-I.D.: mimsy.5258
Posted: Sun Feb  1 20:53:48 1987
Date-Received: Sun, 1-Feb-87 23:17:59 EST
References: <4114@brl-adm.ARPA>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 27

In article <4114@brl-adm.ARPA> escott%deis.uci.edu@icsg.uci.edu
(Scott Menter) writes:
>... is there any reason why you should be able to declare an array
>with zero elements as an automatic variable?

Why not?  It makes sense.  Perhaps it should elicit a warning, since
no members of that array are accessible:  Valid subscripts are in the
range [0..0).

>What's strange is that, on the VAX, the program apparently successfully
>dereferenced bar, both setting a value for "*bar" and then using that value
>later.  How can this be right?

Just luck.

>And, just for the heck of asking, does ANSI C let you make such a
>declaration?

There seems to be a great debate over malloc(0), with some support
as well for empty arrays.  It is trivial to allow either, or to
disallow either; some argue in favour of `catching the programmer's
mistakes for him', while others argue that the construct may not
be a mistake, or may have been written by a machine, and that having
special cases for zero is both unnecessary and ugly.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
UUCP:	seismo!mimsy!chris	ARPA/CSNet:	chris@mimsy.umd.edu