Header <format> implementation status Reference Implementation : Cannot implement with language itself. Need compiler support. Used C++ N STL : Partially implemented with C++ N : Fully implemented with C++ N : Not yet implemented Features Standard Implemented in Concepts formattable Enumerations range_format Classes formatter range_formatter basic_format_parse_context format_parse_context wformat_parse_context basic_format_context format_context wformat_context basic_format_arg basic_format_args format_args wformat_args basic_format_string format_string wformat_string format_error Functions format format_to format_to_n formatted_size vformat vformat_to visit_format_arg ~~ (deprecated in C++26)~~ Deprecated in C++26 make_format_args make_wformat_args Helpers format_kind