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Path: sparky!uunet!think.com!sophists.com!lewis
From: lewis@sophists.com (Lewis G. Pringle)
Subject: Re: Zero-length structures and pointer comparisons
Message-ID: <1992Nov10.185247.14128@sophists.com>
Date: Tue, 10 Nov 1992 18:52:47 GMT
References: <1992Oct28.184135.25475@ucc.su.OZ.AU> <1992Oct30.003946.10484@microsoft.com> <1992Nov4.080805.13496@jyu.fi>
Organization: Sophist Solutions
Lines: 35

In article <1992Nov4.080805.13496@jyu.fi> sakkinen@jyu.fi (Markku Sakkinen) writes:
...
>I would first like to return to a much more important, related problem,
>which somebody brought up here rather recently.
>Namely, there is nothing in the ARM explicitly saying that
>p == q  might not yield 1 even when p and q are pointing at two different
>objects.  This hole makes e.g. some standard idioms in Stroustrup's books
>implementation dependent.

I'd like to ask a related question.

Given code like:

char* start = new char [10];
char* end   = start+10;
char* p     = start;

assert ((p >= start) && (p <= end));		// this is gauranteed by ANSI-C
p += 10;
assert ((p >= start) && (p <= end));		// this is gauranteed by ANSI-C
p = start;
p--;
assert (! ((p >= start) && (p <= end)));	// ???????

Is the last assertion portable? ARM/ANSI-C References?


				LeWiS.



-- 
Reading peoples signatures is a real waste of time.

lewis@sophists.com                                  (Lewis Gordon Pringle, Jr.)