Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!ames!amdcad!crackle!tim
From: tim@crackle.amd.com (Tim Olson)
Newsgroups: comp.lang.c
Subject: Re: programming puzzle (silly)
Message-ID: <24820@amdcad.AMD.COM>
Date: 11 Mar 89 19:57:01 GMT
References: <28336@ucbvax.BERKELEY.EDU> <2821@goofy.megatest.UUCP> <YY6_v5y00UkaI0ZW1_@andrew.cmu.edu>
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In article <YY6_v5y00UkaI0ZW1_@andrew.cmu.edu> bader+@andrew.cmu.edu (Miles Bader) writes:
| From klier@ucbarpa.Berkeley.EDU (Pete Klier):
| > 
| > main(m,n){scanf("%d",&n);for(m=n>0^n>9;n&&m*=n--;);
| > printf(m?"Answer=%d\n":"error\n",m);}
| > 
| > with help from Jeff Conroy (jmconroy@ernie.Berkeley.EDU)
| 
| The compiler on this machine give the following error; is it wrong?
| 
| E "fact.c",L1/C44:	(syntactic)  unexpected symbol:'*='

Interesting -- the program *is* incorrect, because && has higher
precedence than *= so it is parsed as:

	(n&&m) *= n--

which is illegal because (n&&m) is not an lvalue.  Our MetaWare and
Green Hills compilers catch it, but every pcc-based compiler I tried
compiled it with no warnings.  Looking at the assembly-language
generated, it appears that it compiled as:

	n && (m*=n--)

What do other compilers out there do?


	-- Tim Olson
	Advanced Micro Devices
	(tim@amd.com)