Subject: Re: some unusual errors
From: [email-masked] (Lassi A. Tuura)

22 Sep 1998 20:21:57 -0700
Message-ID: <[email-masked]>
References: <[email-masked]>
Reply-To: "Lassi A. Tuura" <[email-masked]>
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Content-Type: TEXT/PLAIN; charset=US-ASCII
To: Michael Richardson <[email-masked]>
Cc: Michael Hirmke <[email-masked]>, [email-masked]

|>   Why would you say "unsigned char"??
|>   It says "int" to me.
|>   So, a signed char should promote to int just fine.

The only negative value allowed with these functions is EOF (if it is
negative)---see the quotes earlier in this thread.  If you have a signed
character that really is negative, it will promote to a negative integer
and you end up with undefined behaviour. gcc is nice enough to give you
a warning about that.  You need to cast the character to `unsigned char'
before using it in the is* predicates.

Cheers,
//lat
--
With sufficient thrust, pigs fly just fine.  However, this is not
necessarily a good idea.  It is hard to be sure where they are going
to land, and it could be dangerous sitting under them as they fly
overhead.  --RFC1925, "The Twelve Networking Truths"

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