From: chris jefferson <caj@cs.york.ac.uk>
To: mrc.lrn@inwind.it
Cc: gcc@gcc.gnu.org
Subject: Re: Pointers in comparison expressions
Date: Tue, 12 Jul 2005 17:03:00 -0000 [thread overview]
Message-ID: <42D3F6D6.9090806@cs.york.ac.uk> (raw)
In-Reply-To: <200507121825.45472.mrc.lrn@inwind.it>
Mirco Lorenzoni wrote:
>Can a pointer appear in a C/C++ relational expression which doesn't test the
>equality (or the inequality) of that pointer with respect to another pointer?
>For example, are the comparisons in the following program legal code?
>
>/* test.c */
>#include <stdio.h>
>
>int main(int argc, char* argv[])
>{
> void *a, *b;
> int aa, bb;
>
> a = &aa;
> b = &bb;
>
>
>
Actually I'm fairly certain at this point this program stops being legal
code, as (I believe) you can only compare pointers which are from the
same allocation (be that an array, malloc, etc).
However, comparing pointers with < is something I do all the time when
writing various kinds of algorithms. For what reason would you want to
see it warned about?
Chris
next prev parent reply other threads:[~2005-07-12 17:03 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-12 16:24 Mirco Lorenzoni
2005-07-12 16:32 ` Daniel Berlin
2005-07-12 16:53 ` Dave Korn
2005-07-12 21:00 ` Andreas Schwab
2005-07-12 21:42 ` Erik Trulsson
2005-07-12 22:09 ` Joe Buck
2005-07-12 22:28 ` Erik Trulsson
2005-07-12 22:38 ` Falk Hueffner
2005-07-12 23:17 ` Joe Buck
2005-07-12 23:28 ` Falk Hueffner
2005-07-13 2:02 ` Joe Buck
2005-07-13 21:42 ` Olivier Galibert
2005-07-12 23:27 ` Michael Meissner
2005-07-12 22:46 ` Joe Buck
2005-07-16 11:49 ` Vincent Lefevre
2005-07-17 16:55 ` Paul Koning
2005-07-18 1:49 ` Vincent Lefevre
2005-07-18 3:13 ` D. Hugh Redelmeier
2005-07-18 13:13 ` Paul Koning
2005-07-18 13:09 ` Paul Koning
2005-07-12 17:03 ` chris jefferson [this message]
2005-07-12 23:18 ` Michael Meissner
2005-07-22 23:20 ` Geoffrey Keating
2005-07-13 13:53 Morten Welinder
2005-07-24 1:13 Paul Schlie
2005-07-26 4:43 ` Geoff Keating
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