From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <zsh-workers-request@math.gatech.edu>
Received: (qmail 1024 invoked from network); 28 Nov 1997 20:16:46 -0000
Received: from math.gatech.edu (list@130.207.146.50)
  by ns1.primenet.com.au with SMTP; 28 Nov 1997 20:16:46 -0000
Received: (from list@localhost)
	by math.gatech.edu (8.8.5/8.8.5) id OAA17807;
	Fri, 28 Nov 1997 14:53:52 -0500 (EST)
Resent-Date: Fri, 28 Nov 1997 14:53:33 -0500 (EST)
From: Andrew Main <zefram@tao.co.uk>
Message-Id: <199711281937.TAA12593@taos.demon.co.uk>
Subject: Re: strange arithmetic
To: mito@aparima.com
Date: Fri, 28 Nov 1997 19:37:05 +0000 (GMT)
Cc: zsh-users@math.gatech.edu
In-Reply-To: <19971128140924.07137@retriever> from "Louis-David Mitterrand" at Nov 28, 97 02:09:24 pm
X-Loop: zefram@tao.co.uk
X-Headers: in preparation
X-Mailer: ELM [version 2.4 PL25]
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Resent-Message-ID: <"r487B1.0.iL4.z4oVq"@math>
Resent-From: zsh-users@math.gatech.edu
X-Mailing-List: <zsh-users@math.gatech.edu> archive/latest/1160
X-Loop: zsh-users@math.gatech.edu
X-Loop: zsh-workers@math.gatech.edu
Precedence: list
Resent-Sender: zsh-workers-request@math.gatech.edu

Louis-David Mitterrand wrote:
>% i=0;while [[ $[++i] < 900 ]];do;echo $i;done

"<" does a string comparison.  For a numeric comparison, you want "-lt".

>% i=0;while ! [[ $[++i] = 900 ]];do;echo $i;done

"=" (or the preferred "==") also does string comparison.  You should
really use "-eq" here.

I've just noticed that this is exactly the opposite convention from Perl.
I can even see why the difference was historically inevitable.

-zefram