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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. http://pubs.opengroup.org/onlinepubs/9699919799/functions/isascii.html > > 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: http://pubs.opengroup.org/onlinepubs/9699919799/functions/isdigit.html > > 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 http://libvirt.org
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