Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: Writing readable code
Message-ID: <6051@brl-smoke.ARPA>
Date: Fri, 3-Jul-87 22:58:34 EDT
Article-I.D.: brl-smok.6051
Posted: Fri Jul  3 22:58:34 1987
Date-Received: Sun, 5-Jul-87 00:17:20 EDT
References: <1158@copper.TEK.COM> <6858@auspyr.UUCP> <17171@cca.CCA.COM> <13008@topaz.rutgers.edu> <1571@sfsup.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 17

In article <1571@sfsup.UUCP> mpl@sfsup.UUCP writes:
>If you read "The Elements of Programming Style" by Kernighan and Plauger (?)
>(which you may or may not agree with), the authors suggest that a test for
>< 0 is better than a test for -1, since a coding error could possibly cause
>a function to return a value that is out of the legal range (> 0) but is not
>the intended error value (-1).

Some people (Dijkstra and Gries among them) no longer believe that this
kind of "conservative" test is preferable to the exact test; they base
this on what it takes to prove an implementation of an algorithm to be
correct.

>Not only that, but on many machines, a test for < 0 may be more
>efficient than a test against a specific value.

I doubt that the difference is detectable (remember, the code just made
a system call!).