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