Path: utzoo!mnetor!uunet!dalcs!thompson
From: thompson@dalcs.UUCP (Michael Thompson)
Newsgroups: comp.bugs.4bsd
Subject: Re: csh arithmetic bug
Message-ID: <2830@dalcs.UUCP>
Date: 11 Apr 88 13:31:52 GMT
References: <23570@ucbvax.BERKELEY.EDU>
Reply-To: thompson@dalcs.UUCP (Michael Thompson)
Organization: Math, Stats & CS, Dalhousie University, Halifax, NS, Canada
Lines: 23

In article <23570@ucbvax.BERKELEY.EDU> ph@miro.Berkeley.EDU (Paul Heckbert) writes:
>Beware of doing arithmetic in csh, it's buggy!
>The command	@ x = 0 - 1 + 2		sets x to -3	(should be 1)
>The command	@ x = 0 - 1 - 2		sets x to 1	(should be -3)
>(same error with Sun UNIX 3.5 on Sun3 and 4.3 BSD on Vax780)
>
>csh must be parsing right-associatively by mistake!
>Division has a similar problem.
>It's hard to believe that a bug like this would persist for 8 years.

	The following is extracted from the csh man page:
     *   /   %
          multiplication, division, remainder  (These  are  right
          associative,  which  can  lead  to  unexpected results.
          Group combinations explicitly with parentheses.)
     +   -
          addition, subtraction (also right associative)

-- 
<<<<<<******>>>>>>
Michael A. Thompson, Dept. Math, Stats, & C.S., Dalhousie U., Halifax, N.S.
thompson@dalcs.uucp | thompson@cs.dal.cdn | thompson@dal1.bitnet
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