From: Nathan Sidwell <nathan@codesourcery.com>
To: Nicholas Nethercote <njn@cs.utexas.edu>
Cc: gcc@gcc.gnu.org
Subject: Re: Where does the C standard describe overflow of signed integers?
Date: Mon, 11 Jul 2005 15:15:00 -0000 [thread overview]
Message-ID: <42D28CFF.6040208@codesourcery.com> (raw)
In-Reply-To: <Pine.LNX.4.63.0507110948081.20206@charco.cs.utexas.edu>
Nicholas Nethercote wrote:
> Hi,
>
> There was recently a very long thread about the overflow behaviour of
> signed integers in C. Apparently this is undefined according to the C
> standard. I searched the standard on this matter, and while I did find
> some paragraphs that described how unsigned integers must wrap around
> upon overflow, I couldn't find anything explicit about signed integers.
> Can someone point me to the relevant part(s) of the standard?
c99 6.5 para 5 (overflow is undefined) & 6.3.1.3 (conversions to unsigned type
obey modulo laws)
c++ 5 para 5 (overflow is undefined, unless otherwise stated) & 3.9.1 para 4
(unsigned types obey modulo laws)
I cannot find, in c99, a statement that all unsigned arithmetic obeys modulo
laws -- only that integral conversions to them do.
nathan
--
Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC
nathan@codesourcery.com :: http://www.planetfall.pwp.blueyonder.co.uk
next prev parent reply other threads:[~2005-07-11 15:15 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-11 14:58 Nicholas Nethercote
2005-07-11 15:07 ` Dave Korn
2005-07-11 16:07 ` Nicholas Nethercote
2005-07-11 17:04 ` Dave Korn
2005-07-11 15:15 ` Nathan Sidwell [this message]
2005-07-11 15:23 ` Dave Korn
2005-07-11 15:18 ` Overflow in Fortran (was: Where does the C standard describe overflow of signed integers?) Paul Brook
2005-07-12 23:13 ` Where does the C standard describe overflow of signed integers? Michael Meissner
2005-07-14 1:10 Paul Schlie
2005-07-14 1:59 ` Robert Dewar
2005-07-14 5:28 ` Paul Schlie
2005-07-14 17:57 ` Matthew Woodcraft
2005-07-14 18:36 ` Paul Koning
2005-07-14 19:09 Paul Schlie
2005-07-14 19:13 ` Robert Dewar
2005-07-14 19:28 ` Paul Schlie
2005-07-14 19:33 ` Robert Dewar
2005-07-14 20:13 ` Paul Schlie
2005-07-15 13:20 ` Georg Bauhaus
2005-07-15 13:33 ` Georg Bauhaus
2005-07-15 14:31 ` Dave Korn
2005-07-16 12:04 ` Georg Bauhaus
2005-07-16 14:26 ` Paul Schlie
2005-07-15 15:03 ` Paul Schlie
2005-07-16 12:12 ` Georg Bauhaus
2005-07-14 20:35 ` Paul Koning
2005-07-14 21:58 ` Paul Schlie
2005-07-15 7:04 ` Avi Kivity
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