problematic document for isascii(3)

Fri May 24 08:23:00 GMT 2013

The POSIX wording seems strange to me.
It says:
`The isdigit() and isdigit_l() functions shall test whether c is a
character of class digit in the current locale, or in the locale
represented by locale, respectively.'

But the ansi draft says:
`The only functions in $4.3 whose behavior is not affected by the
current locale are isdigit and isxdigit .'

2013/5/23 Eric Blake <>:
> On 05/23/2013 07:21 AM, ntysdd wrote:
>> Hi,
>> I found something buggy in the document.
>> The doc says "`isascii' is ANSI C", but it isn't.
>> It is a BSD extension.
> Actually, it is also POSIX, but you are correct that it is not C.
>> Also the doc for isdigit says
>> "It is defined only when `isascii'(C) is true or C is EOF."
> This is a lie; isascii(128) returns false, but isdigit(128) is well=defined.
>> But isdigit is ANSI C so it should not rely on isascii.
>> And after reading the ansi draft, I think isdigit is defined
>> for anything representable as an unsigned char (plus EOF).
> Correct, that is also the POSIX wording:
>> By the way, the doc says isdigit is a macro using a table.
>> I don't think it need be implemented in this way because
>> something like '0' <= C && C<='9' is good enough.
> That's still a table lookup, of sorts.  The implementation can do
> whatever it wants under the hood, as long as the as-if rule is honored
> and you get the same results.
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library

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