Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!rex!ames!haven!adm!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.lang.c
Subject: Re: % operator with negatives
Message-ID: <7461:Dec1310:04:0990@kramden.acf.nyu.edu>
Date: 13 Dec 90 10:04:09 GMT
References: <1990Dec12.185714.7169@mp.cs.niu.edu> <1990Dec12.205416.26622@zoo.toronto.edu>
Organization: IR
Lines: 13

In article <1990Dec12.205416.26622@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
> In article <1990Dec12.185714.7169@mp.cs.niu.edu> t901908@mp.cs.niu.edu (Joe Adamo) writes:
> >I know this may sound silly, but what is the effect of using the 
> >% (mod) operator with negatives?  I can't seem to find any info on it.
> If you're asking the obvious question -- "what's the sign of the remainder?",
> i.e. "which way does the rounding of the quotient go?" -- there is no
> portable answer.  It's implementation-specific.

And if you're asking ``Where is the information on it?'', the answer is
that a % b is defined so that (a / b) * b + (a % b) equals a. It's the
ambiguous definition of / that makes % so useless with negatives.

---Dan