Path: utzoo!utgpu!attcan!uunet!mcvax!hp4nl!bsiao!tvdl
From: tvdl@bsiao.UUCP (Timo van der Laan)
Newsgroups: comp.lang.c
Subject: Conversion of unsigned long to double
Message-ID: <515@bsiao.UUCP>
Date: 21 Apr 89 13:43:56 GMT
Reply-To: tvdl@bsiao.UUCP (Timo van der Laan)
Organization: POSTBANK N.V., Amsterdam
Lines: 33

The C-compiler for IX370 (running on a 9370 machine) treats an
unsigned long as a signed long if that unsigned long is assigned to
a double. (See the program below).

Is this behavior permitted in ANSI?

**** program ****
main(){
	unsigned long	l;
	double	d;

	l=2100000000L;
	d=l;
	printf("%11u %13.0f\n",l,d);
	l=2200000000L;
	d=l;
	printf("%11u %13.0f\n",l,d);
}

**** Output on IBM 9370 (IX370)**** | **** Output on a Vax (4.3 bsd) ****
 2100000000    2100000000           | 2100000000    2100000000
 2200000000   -2094967296           | 2200000000    2200000000

I found this just before a large program went into production.
If it's a bug, I'll bet that IBM will change the manual instead of
repairing the compiler. (Just as they did after I told them that
rm -rf ../dir did not remove the directory because of the ../ )

--
 Timo van der Laan, Postbank N.V., room 4.94        ...mcvax!hp4nl!bsiao!tvdl
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