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From: gwyn@brl-smoke.UUCP
Newsgroups: comp.lang.c
Subject: Re: ANSI really does want you to == float values.
Message-ID: <5756@brl-smoke.ARPA>
Date: Tue, 14-Apr-87 02:52:43 EST
Article-I.D.: brl-smok.5756
Posted: Tue Apr 14 02:52:43 1987
Date-Received: Wed, 15-Apr-87 04:47:54 EST
References: <6909@watmath.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Distribution: comp
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 10

In article <6909@watmath.UUCP> rbutterworth@watmath.UUCP (Ray Butterworth) writes:
>The ANSI standard defines functions such as strtod() that return
>a double value, HUGE_VAL, upon failure.  That seems to imply that
>the following pieces of code all should do the comparison the same
>way.

As you point out, the exact equality comparison may fail on some systems.
Therefore, you should not use it.  Most functions returning HUGE_VAL also
historically have some other error indicator as well.  I wish X3J11 had
adopted matherr(), which is a fairly good way to intercept such exceptions.