std::iswalpha

#include <clocale>
#include <cwctype>
#include <iostream>

int main()
{
    wchar_t c = L'\u0b83'; //    ('')

    std::cout << std::hex << std::showbase << std::boolalpha;
    std::cout << "   , iswalpha(" << (std::wint_t)c << ") = "
              << (bool)std::iswalpha(c) << '\n';

    std::setlocale(LC_ALL, "en_US.utf8");
    std::cout << "  , iswalpha(" << (std::wint_t)c << ") = "
              << (bool)std::iswalpha(c) << '\n';
}