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From: nils@guru.stgt.sub.org (Cornelis van der Laan)
Subject: Re: FreeBSD 1.1.5 -- Bug in /usr/bin/leave
Reply-To: nils@ims.uni-stuttgart.de
Sender: news@guru.stgt.sub.org (Cornelis van der Laan)
Nntp-Posting-Host: localhost.ims.uni-stuttgart.de
Organization: Mehr Anarchie !
Message-ID: <NILS.94Aug18045517@guru.stgt.sub.org>
References: <NILS.94Aug14230659@guru.stgt.sub.org> <1994Aug15.034212.20767@cs.brown.edu>
<NILS.94Aug16025340@guru.stgt.sub.org>
<1994Aug17.172837.4215@cs.brown.edu>
In-Reply-To: mhw@cs.brown.edu's message of Wed, 17 Aug 1994 17:28:37 GMT
Date: Thu, 18 Aug 1994 02:55:17 GMT
Lines: 34
In article <1994Aug17.172837.4215@cs.brown.edu> mhw@cs.brown.edu (Mark Weaver) writes:
> In article <NILS.94Aug16025340@guru.stgt.sub.org>,
> Cornelis van der Laan <nils@ims.uni-stuttgart.de> wrote:
> >> Your fix doesn't change the program at all. In C, "&&" has a higher
> >> precedence than "||", and both have a lower precedence than the
> >> comparison operators. I don't know why you thought this changed
> >> anything, but I'm sure it didn't.
> >
> >You're right, of course. My patch was reversed by some strange
> >mistake. The error in the code is that && has higher precedence over
> >all the preceding || expressions, which it shouldn't have.
>
> No, I'm saying that the two versions of the program are EQUIVALENT,
> regardless of which way the patch goes. Due to the normal precedence of
> operators in C, the parentheses are irrelevant.
>
> "&&" has higher precedence than "||" in C, even without parentheses.
Sure,
a || b || c && d
is equivalent to
(a || b || c) && d
nobody doubts that.
But parenthesis do matter in the expression
a || b || (c && d)
Have you tested the program?
Nils.
--
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Cornelis van der Laan -- nils@ims.uni-stuttgart.de
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