Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!ucbvax!agate!apple!motcsd!hpda!hpcuhb!hpcllla!hpclisp!hpclwjm!walter
From: walter@hpclwjm.HP.COM (Walter Murray)
Newsgroups: comp.lang.c
Subject: Re: floating point constants
Message-ID: <660047@hpclwjm.HP.COM>
Date: 27 Jul 89 18:45:43 GMT
References: <1925@arisia.Xerox.COM>
Organization: Hewlett-Packard Calif. Language Lab
Lines: 25

>>Is this a valid C program?

>>main()
>>{
>>        printf("%f\n", 1.0/0.0);
>>        printf("%f\n", -1.0/0.0);
>>        printf("%f\n", 0.0/0.0);
>>}

>It's certainly not strictly conforming.  Division by zero is handled in
>an implementation-dependent way, including fatal compile-time error.

Another interpretation is that it's a valid program, as long as
you don't try to run it!  An expression involving division by
zero is not illegal unless that expression has to be evaluated,
in which case behavior is undefined.

Under ANSI C, I think it's clear that the following program is
valid, and prints the value 1.

main() { printf("%d\n", 2.0||1.0/0.0); }

Walter Murray
Not speaking for X3J11
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