Re: Usage of isspace and friends

From: Linus Torvalds <torvalds@osdl.org>
Date: Oct 13, 2005, 15:04 UTC
Message-ID: <Pine.LNX.4.64.0510130756550.15297@g5.osdl.org>
In-Reply-To: <7vachd6hdx.fsf@assigned-by-dhcp.cox.net>

On Wed, 12 Oct 2005, Junio C Hamano wrote:

> 
> Huh?  isspace is "int isspace(int)".  Presumably standard
> integral promotion rules applies here whether char is signed or
> unsigned, doesn't it?

No.

The input range for the "isxxxxx()" macros is the same as the range for the "[f]getc[h]()" family: unsigned char + EOF (the latter usually being -1).

So Morten is right - if you have a "char *", it should not be dereferenced and used directly, although I think glibc does the right thing (and, in fact, I can't understand why the standards haven't been updated to do the right thing: it's _not_ that hard. In fact, it should be trivial apart from the special case of "255" that looks undistinguishable from EOF in signed char representation).

I'm almost goign to suggest that we do our own ctype.h, just to get the sane semantics: we want locale-independence, _and_ we want the right signed behaviour. Plus we only use a very small subset of ctype.h anyway (isspace, isalpha, isdigit and isalnum).

			Linus