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Re: signed vs unsigned pointer warning
Paul Jarc wrote:
> > No, (unsigned)-1 does not turn into 255, it turns into a very large
> > number.
>
> But character 255, as a signed char, is also -1, and so will also
> become the same large number. The caller must cast char to unsigned
> char to ensure that EOF is distinct. *Only* the caller can make the
> distinction reliably, since only the caller knows whether this
> particular -1 is supposed to be EOF.
Is it necessary for them to be distinct?
I didn't see any rule in "man isalpha" saying anything about EOF
other than it's accepted as an argument value.
In particular, is it ok if isalpha(EOF) == isalpha(255), whatever the
value of isalpha(255)?
Or is there a rule that is*(EOF) must return 0?
-- Jamie