Path: utzoo!mnetor!uunet!yale!mfci!root
From: root@mfci.UUCP (SuperUser)
Newsgroups: comp.lang.c
Subject: Re: unsigned comparsions
Message-ID: <379@m3.mfci.UUCP>
Date: 2 May 88 17:44:55 GMT
References: <12578@brl-adm.ARPA> <1988Mar25.172355.348@utzoo.uucp> <375@m3.mfci.UUCP> <11304@mimsy.UUCP>
Reply-To: karzes@mfci.UUCP (Tom Karzes)
Organization: Multiflow Computer Inc., Branford Ct. 06405
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In article <11304@mimsy.UUCP> chris@mimsy.UUCP (Chris Torek) writes:
>[They were equivalent.  The comparison was |unsigned char| != -1, which
>---provided |char| is shorter than |int|---is indeed always true, in both
>the existing sign preserving system and in the value preserving system in
>the dpANS.]

Oops, I hadn't noticed that the routine was returning an unsigned char, I
only noticed the unsigned.  Yes, assuming chars are shorter than ints then
an unsigned char, when zero-padded out to a full int, will never have the
same bit pattern as -1.  (I should add that I've always thought that C
routines which return chars or shorts should be avoided, and that such
data types should only be used for arrays and structure members, since C
prefers to deal with full size integers, and using chars and shorts will
at best cost you a bunch of useless sign extensions/zero fills and
truncations, and at worst will cause unexpected results.)