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From: jsdy@hadron.UUCP (Joseph S. D. Yao)
Newsgroups: comp.lang.c
Subject: Re: bit patterns of all ones
Message-ID: <406@hadron.UUCP>
Date: Fri, 2-Jan-87 07:31:56 EST
Article-I.D.: hadron.406
Posted: Fri Jan  2 07:31:56 1987
Date-Received: Fri, 2-Jan-87 20:59:36 EST
References: <1382@hoptoad.uucp> <690001@hplsla.HP.COM> <1527@hoptoad.uucp> <595@mrstve.UUCP>
Reply-To: jsdy@hadron.UUCP (Joseph S. D. Yao)
Organization: Hadron, Inc., Fairfax, VA
Lines: 14
Summary: Casts convert.  2^n-1 is (typically) all ones.

In article <595@mrstve.UUCP> rjk@mrstve.UUCP (Richard Kuhns) writes:
>I don't understand.  On a ones-complement machine, -1 is represented by
>11111110(binary) = -1 (decimal, ones complement, signed)
>If the ... value above is cast to unsigned, we end up with 254(decimal).

Casts convert.  "The value is the least unsigned integer congruent
to the signed integer (modulo 2^wordsize)." -C REF 6.5, Unsigned.
Casts do not necessarily maintain the same bit pattern.

[inews placater]
-- 

	Joe Yao		hadron!jsdy@seismo.{CSS.GOV,ARPA,UUCP}
			jsdy@hadron.COM (not yet domainised)