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From: schwartz@groucho.cs.psu.edu (Scott Schwartz)
Newsgroups: comp.lang.misc
Subject: Re: Formal definitions (Re: ada-c++ productivity)
Message-ID: <uj1Gmuev1@cs.psu.edu>
Date: 22 Apr 91 00:56:04 GMT
References: <1726@optima.cs.arizona.edu> <29344@dime.cs.umass.edu>
	<12318@dog.ee.lbl.gov> <14633@ulysses.att.com>
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In-Reply-To: kpv@ulysses.att.com's message of 21 Apr 91 17:24:59 GMT
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In article <14633@ulysses.att.com> kpv@ulysses.att.com (Phong Vo[drew]) writes:
   Just to make this concrete, the following example is mathematically correct
   given all the usual definitions of the C operators. It is incorrect because
   it is not portable.

The "usual" definitions usually assume various nonportable things;
part of the ANSI effort was to better specify the language.  As an
aside, K&R2 says that if the pointer resulting from address arithmatic
points outside the array, the effect is undefined.  Surely you
couldn't show that example to be "mathematically correct" given that
rule.