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From: daveb@rtech.UUCP (Dave Brower)
Newsgroups: net.lang.c,net.unix
Subject: C Quiz:  why does this SIGFPE?
Message-ID: <201@rtech.UUCP>
Date: Sat, 12-Apr-86 11:33:22 EST
Article-I.D.: rtech.201
Posted: Sat Apr 12 11:33:22 1986
Date-Received: Sat, 19-Apr-86 04:17:11 EST
Distribution: net
Organization: Relational Technology Inc, Alameda CA
Lines: 35
Xref: watmath net.lang.c:8611 net.unix:7656

This is a quiz.  The answer will be posted in a week or so.  Don't
post a reply unless you need to impress your collegues.

Why will this code sometimes generate SIGFPE at the indicated point?

/* An example.  Does nothing usefull */

int zerf( f )
float * f;
{
	*f = 0.0;
	return( (int)f );
}

void show( flag, i, f )
int flag, i; float f;
{
	if(flag) printf( "i is %d\n", i )
	else printf( "f is %f\n", f )
}


void dynomite( flag, i )
int flag, i;
{
	float f;

	if( flag ) i = zerf( &f );
	else show( flag, i, f );	/* <-- SIGFPE happens here */
}

-- 
Red:   "Whadda ya got that big nose for, granny?"
Wolf:  "Just to HAVE, see!"
{amdahl, sun, mtxinu, cbosgd}!rtech!daveb