Re: Usage of isspace and friends

From: Antti-Juhani Kaijanaho <antti-juhani@kaijanaho.info>
Date: Oct 13, 2005, 08:29 UTC
Message-ID: <434E1AE8.9010509@kaijanaho.info>
In-Reply-To: <7vachd6hdx.fsf@assigned-by-dhcp.cox.net>

Junio C Hamano wrote:

Show 11 quoted lines

> Morten Welinder <mwelinder@gmail.com> writes:
>>Since str[9] is of type char it should not be used as a argument to
>>isspace directly,
>>but rather be cast to unsigned char:
>>
>>    ... isspace((unsigned char)str[9]);
> 
> 
> Huh?  isspace is "int isspace(int)".  Presumably standard
> integral promotion rules applies here whether char is signed or
> unsigned, doesn't it?

Of course, but that's not the issue. isspace treats its parameter as if it had been converted from unsigned char to int. If char is signed, ïsspace will mistreat those characters that have a negative value. Then again, I don't think a space character, one that the C locale regards as such, anyway, wiill ever have a negative value, so the issue is rather academic.

> The snippet you quoted is from apply.c, and I would say what is
> more problematic is that we do not force C locale while parsing
> the diff

Quite true. One reason I tend to avoid the standard is* functions in my own code.

-- 
Antti-Juhani