> > isdigit(3) says the prototype is "int isdigit(int c);", so #1 would seem
> > correct.
> 
> No, it is completely wrong and the VERY reason that gcc gives a warning
> in this case.
> 
> The domain of all the isxxx() functions is EOF plus all the values of
> unsigned char, typically -1..255.  So if your signed char buf[n] contains
> a negative value then the wrong things happen unless you cast to
> unsigned char first.
> 
> Remember that isalpha() can be valid for -ve chars.
> 
> Of course, things will go terribly wrong if isdigit() returns non-zero
> for anything other that '0'..'9'.

Eh, I see. Sorry for noise, I must be on coke this morning... :-(

	Regards,
		-- Jachym Holecek