Re: Usage of isspace and friends

From: Linus Torvalds <torvalds@osdl.org>
Date: Oct 13, 2005, 15:56 UTC
Message-ID: <Pine.LNX.4.64.0510130847190.15297@g5.osdl.org>
In-Reply-To: <434E8117.3090102@zytor.com>

On Thu, 13 Oct 2005, H. Peter Anvin wrote:

> 
> Because of the special case of 255 which looks indistinguishable from EOF,
> therefore making it required?

Yeah, and I agree, that was a mistake. It could have been fixed by making EOF be MIN_INT (or any other value outside the range of either "unsigned char" or "signed char" - preferably still negative), but there are probably programs that depend on it being -1.

The stupid thing I just posted doesn't care. It happens to return 0 for EOF for all cases, but that's a side effect of (a) not doing locales (so 255 is never printable or alpha) and (b) not even implementing iscntrl().

In general, the rule for ctype and EOF _should_ have been that it's part of an acceptable input range, but that the return value is undefined ;)

(Which would allow you to test EOF later, and not worry about any faults).

		Linus