记一种c++字符串格式化方法

std::string str_fmt(const char * _Format, ...)
        {
            std::string _str;
            va_list marker = NULL;
            va_start(marker, _Format);

            size_t num_of_chars = _vscprintf(_Format, marker);
            _str.resize(num_of_chars);
            vsprintf_s((char *)_str.c_str(), num_of_chars + , _Format, marker);
            va_end(marker);
            return _str;
        }