Re: [boost] [Convert] std::isspace requires unsigned #28

On 21/03/2017 13:46, Vladimir Batov via Boost wrote:

Thanks, Gavin, indeed I should have a dig in char_traits before re-inventing the wheel. Thanks.

There's also std::ctype::is(), although the call syntax for that seems a bit more cumbersome. Also at least according to cppreference.com it hasn't been extended for the new 16-bit and 32-bit C++11 char types. I don't know if that means anything.

What about iswspace()? Does it have the same problem as std::isspace(), i.e. needs an explicit cast? Seems unlikely...

I think it's probably good practice to use char_traits<>::to_int_type() for that too, since the parameter type is wint_t rather than wchar_t, and that's the "right" way to do that conversion. As Peter said in practice it probably wouldn't cause any bugs without that since it would be weird for wchar_t to be signed, but as both the sign and size of the type is implementation-defined it's not actually illegal for that to be the case. (And you're even less likely to notice on platforms where wchar_t is 32-bit or larger, but again that's implementation-defined.)