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From: dricejb@drilex.UUCP (Craig Jackson drilex1)
Newsgroups: comp.lang.c
Subject: Re: Zero Length Arrays Allowed in C Standard?
Message-ID: <6736@drilex.UUCP>
Date: 9 Dec 89 15:00:21 GMT
References: <2298@jato.Jpl.Nasa.Gov> <11715@smoke.BRL.MIL> <480@codonics.COM> <8141@cg-atla.UUCP> <7349@quick.COM> <7227@ficc.uu.net>
Reply-To: dricejb@drilex.UUCP (Craig Jackson drilex1)
Organization: DRI/McGraw-Hill, Lexington, MA
Lines: 31

In article <7227@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
>In article <7349@quick.COM> srg@quick.COM (Spencer Garrett) writes:
>> But this "convenience" is in no way implementation specific.  It is
>> cleanly implementable in any environment which is capable of hosting
>> C at all.
>
>Including the infamous Burroughs A-series processors?
>`-_-' Peter da Silva. +1 713 274 5180. <peter@ficc.uu.net>.
> 'U`  Also <peter@ficc.lonestar.org> or <peter@sugar.lonestar.org>.

I think the "convenience" referred to was the practice of putting an
array of length 1 (in the absence of zero-length arrays) at the end
of the structure.  You may rest assured that A-Series C will handle
this as well as the next compiler.  Which means that if you malloc'ed the
space, the malloc'ed size is what matters.

The implementors of A-Series C knew that this sort of thing was rampant,
and therefore implemented pointed-to objects using a simulated linear address
space.

They do special-case things which are not pointed to; if one declares an
array:
   int a[1];
and *never* point to it, then referencing a[1] will get you an interrupt.

Note: because of this pointed-to rule, a[1] and *(a+1) can have dramatically
different compilations.
-- 
Craig Jackson
dricejb@drilex.dri.mgh.com
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