Date: Tue, 10 Feb 1998 16:49:12 +0100 (MET)
From: Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
To: Vik Heyndrickx <Vik DOT Heyndrickx AT rug DOT ac DOT be>
cc: DJ Delorie <dj AT delorie DOT com>, djgpp-workers AT delorie DOT com
Subject: Re: char != unsigned char... sometimes, sigh (long)
In-Reply-To: <34E00C53.175A@rug.ac.be>
Message-ID: <Pine.LNX.3.93.980210162720.32596C-100000@acp3bf>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Precedence: bulk

On Tue, 10 Feb 1998, Vik Heyndrickx wrote:

> - EOF is an element of the 'signed char' range which means that no
> matter what trickery is applied, only 256 distinct values can be
> represented of which EOF is one. 

> This has as a consequence that locales
> that have a real character defined for value (char)255 (i.e. EOF) cannot
> be supported by ANY is* macro's, no matter how smart implemented. 

I may sound repetitive, but that's not the full truth on this: they *can*
support it. The only thing they can't do is to magically fix up
non-portable programs that blindly call isalpha(c) for a 'char' value,
instead of the correct isalpha((unsigned char)c). As I consider such
programs to be buggy, I fail to see a problem with not supporting them. 

I fully agree with Eli: we shouldn't change such a rather fundamental
design decision just to make broken user program turn un-broken. 

> - many users do not expect that '`' (the Greek letter alpha with EASCII
> value 224 in DOS CP 437 or 850) is not equal to 224. IMHO, this is
> strongly counterintuitive. This triggers unexpected (and never wanted)
> outputs in printf("%d", ...) and printf ("%u", ...) statements.

I don't think we should pay that much attention to what users _expect_,
even more so if they expect the wrong things... E.g., I can't see any good
reason why anyone should 'printf("%d", '`'). If you want a char to
represent a *number*, then why (other than for the IOCCC)  would you want
to assign a value in '' notation to it? Users who mix up the use of 'char'
for actual characters, and for 'small integers' might as well get what
they asked for. 

> - All DOS compilers that I know about (not many), use 'unsigned char' by
> default. SGI uses 'unsigned char' ;)

But I think all of them can be told to use 'signed char' instead. Even
way old Turbo C 2 could.

> - A char can be used as an array subscript, especially in translation
> tables. Most of the time (99%) the user does not expect that this value
> can be negative.

I doubt you have enough statistical data to justify such a claim :-)


Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.