#include <iostream>
    #include <regex>
    #include <string>

    int main()
    {
        std::basic_string<char32_t> reg = U"^\\w";

        try
        {
            std::basic_regex<char32_t> tagRegex(reg);
        }
        catch(std::exception &e)
        {
            std::cout << e.what() << std::endl;
        }

        return 0;
    }