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Path: utzoo!utgpu!utfyzx!sq!msb
From: msb@sq.UUCP
Newsgroups: comp.lang.c++,comp.lang.c
Subject: Re: bug re unsigned to signed conversion? (side comment)
Message-ID: <1987May29.122541.27690@sq.uucp>
Date: Fri, 29-May-87 12:25:41 EDT
Article-I.D.: sq.1987May29.122541.27690
Posted: Fri May 29 12:25:41 1987
Date-Received: Sat, 30-May-87 10:51:02 EDT
References: <4626@columbia.UUCP> <4605@utah-cs.UUCP>
Reply-To: msb@sq.UUCP (Mark Brader)
Organization: SoftQuad Inc., Toronto
Lines: 13
Xref: utgpu comp.lang.c++:264 comp.lang.c:2147
Checksum: 23942
Summary: (unsigned)-1 guaranteed == max unsigned

Donn Seeley (donn@utah-cs.UUCP) writes:
> ... on a two's complement machine, '(unsigned) -1'
> is the largest unsigned integer.

Actually, (unsigned) -1 should be the largest unsigned int on ANY machine.
	K&R Appendix A ref: section 6.5 on page 184
	ANSI Oct.1 draft ref: section 3.2.1.2 on page 28

What IS true only on a 2's complement machine is that converting a
negative number to unsigned does not change the bit pattern.

Mark Brader, SoftQuad Inc., Toronto, utzoo!sq!msb
#define	MSB(type)	(~(((unsigned type)-1)>>1))