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From: msb@sq.uucp (Mark Brader)
Date: Sun, 6-Mar-88 18:54:19 EST
Message-ID: <1988Mar6.185419.25314@sq.uucp>
Newsgroups: comp.lang.c
Subject: Re: Signedness of chars
References: <23209@ucbvax.BERKELEY.EDU> <7413@brl-smoke.ARPA>
Reply-To: msb@sq.UUCP (Mark Brader)
Organization: SoftQuad Inc., Toronto

> > ...  That is, how many programs would break if
> > `unsigned char' and `char' were the same type?

Doug Gwyn notes:
> The most common portability error in this regard is
> 	char c;
> 	while ((c = getchar()) != EOF)
> 		...
[c should of course be int]

In fact, this is a bug in any case, if the code is supposed to handle binary
data.  On machines where chars are signed, this loop will wrongly terminate
as soon as it reads a byte containing the value (char)EOF, i.e. usually 0xFF.

I have encountered programs that failed in precisely this way.

Mark Brader			"When a supposedly indivisible transaction
SoftQuad Inc., Toronto		 fails to complete properly, this is known
utzoo!sq!msb, msb@sq.com	 as an atomic bomb."   -- Peter Neumann