template< class OutputIt >
OutputIter format( OutputIt out,
const char_type* fmt_first, const char_type* fmt_last,
std::regex_constants::match_flag_type flags =
std::regex_constants::format_default ) const; (1) (since C++11) template< class OutputIt, class ST, class SA >
OutputIter format( OutputIt out,
const basic_string<char_type,ST,SA>& fmt,
std::regex_constants::ma