From: Jamie Lokier <jamie@shareable.org>
To: Joe Buck <Joe.Buck@synopsys.com>
Cc: Nick Ing-Simmons <nick@ing-simmons.net>,
gcc@gcc.gnu.org, "'Morten Welinder'" <terra@gnome.org>,
Dave Korn <dk@artimi.com>
Subject: Re: signed vs unsigned pointer warning
Date: Fri, 08 Oct 2004 18:24:00 -0000 [thread overview]
Message-ID: <20041008172801.GB13758@mail.shareable.org> (raw)
In-Reply-To: <20041008100853.A2207@synopsys.com>
Joe Buck wrote:
> No, (unsigned)-1 does not turn into 255, it turns into a very large
> number. You cannot store EOF in a char. Here's a bug fix:
>
> table_lookup[1U+(unsigned)(c)]
>
> Now EOF goes into slot 0.
The trouble is that char 255 (or char -1 depending on your point of
view) _might_ also go into slot 0, depending on the type of c and how
it was passed.
Do the standards require anything about the result of is*(EOF), or do
the functions simply have to accept that as an argument?
In any case, code which writes:
char c = ... ;
...
if (isspace(c)) {
...
}
Surely deserves a warning from the compiler, just because it'll fail
on some OSes.
-- Jamie
next prev parent reply other threads:[~2004-10-08 17:28 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-22 16:43 Morten Welinder
2004-09-22 17:17 ` Paul Koning
2004-09-22 17:27 ` Morten Welinder
2004-09-22 17:49 ` Dave Korn
2004-09-22 17:20 ` Dave Korn
2004-09-23 1:31 ` Andreas Schwab
2004-09-23 12:29 ` Dave Korn
2004-09-23 18:57 ` Joe Buck
2004-09-23 19:38 ` Dave Korn
2004-09-27 2:04 ` Jamie Lokier
2004-10-08 13:29 ` Nick Ing-Simmons
2004-10-08 13:32 ` Dave Korn
2004-10-08 17:20 ` Joe Buck
2004-10-08 17:28 ` Paul Jarc
2004-10-08 17:59 ` Joe Buck
2004-10-08 18:15 ` Dave Korn
2004-10-08 18:22 ` Joe Buck
2004-10-08 18:24 ` Jamie Lokier [this message]
2004-10-08 19:57 ` Paul Jarc
2004-10-09 7:05 ` Jamie Lokier
2004-10-09 8:48 ` Paul Jarc
2004-10-11 16:34 ` Richard Earnshaw
2004-10-08 18:57 ` Morten Welinder
2004-10-08 20:59 ` Matthias B.
2004-10-08 22:34 ` Paul Koning
2004-10-10 2:03 ` Matthias B.
2004-10-09 1:39 ` Andreas Schwab
2004-10-11 0:11 ` Kai Henningsen
-- strict thread matches above, loose matches on Subject: below --
2004-09-21 20:52 Richard Henderson
2004-09-21 22:36 ` Linus Torvalds
2004-09-22 14:35 ` Dave Korn
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