utf8 conversion tools

utf8_utils.cpp

    std::string wstring_to_utf8(const std::wstring& src) {
        std::string out_str;
#ifdef _WIN32
        utf8::utf16to8(src.begin(), src.end(), std::back_inserter(out_str));
#else
        utf8::utf32to8(src.begin(), src.end(), std::back_inserter(out_str));
#endif
        return out_str;
    }


    std::wstring utf8_to_wstring(const std::string& src) {
        std::wstring out_str;
#ifdef _WIN32
        utf8::utf8to16(src.begin(), src.end(), std::back_inserter(out_str));
#else
        utf8::utf8to32(src.begin(), src.end(), std::back_inserter(out_str));
#endif
        return out_str;
    }