Utilities library
Language support
Type support (basic types, RTTI)
Library feature-test macros (C++20)
Dynamic memory management
Program utilities
Coroutine support (C++20)
Variadic functions
Debugging support
Three-way comparison
General utilities
Date and time
Function objects
Formatting library (C++20)
Relational operators (deprecated in C++20)
Integer comparison functions
Swap and type operations
Common vocabulary types
Elementary string conversions

Defined in header <format>
template< ranges::input_range R, class CharT >
struct range-default-formatter<range_format::map, R, CharT>;
(since C++23)
(exposition only*)

The class template range-default-formatter for range types is specialized for formatting range as a map of keys to values if std::format_kind<R> is std::range_format::map.


[edit] Member types

Member type Definition
maybe-const-map (private) /*fmt-maybe-const*/<R, CharT>
(exposition-only member type*)
element-type (private) std::remove_cvref_t<ranges::range_reference_t<maybe-const-map>>

[edit] Member objects

Member name Definition
underlying_ (private) the underlying formatter of type std::range_formatter<element-type, CharT>
(exposition-only member object*)

[edit] Member functions

constructs a range-default-formatter
(public member function)
parses the format specifier as specified by range-format-spec
(public member function)
writes the range formatted output as specified by range-format-spec
(public member function)


constexpr range-default-formatter();

Equivalent to: underlying_.set_brackets(STATICALLY_WIDEN<CharT>("{"), STATICALLY_WIDEN<CharT>("}"));
underlying_.underlying().set_brackets({}, {});
underlying_.underlying().set_separator(STATICALLY-WIDEN<charT>(": "));

where STATICALLY_WIDEN<CharT>("...") is "..." if CharT is char, and L"..." if CharT is wchar_t.

The program is ill-formed unless:

  • element-type is a specialization of std::pair, or
  • element-type is a specialization of std::tuple and std::tuple_size_v<element-type> is 2.


template< class ParseContext >
constexpr auto parse( ParseContext& ctx ) -> ParseContext::iterator;

Equivalent to return underlying_.parse(ctx);.

Returns an iterator past the end of the range-format-spec.


template< class FormatContext >
auto format( maybe-const-map& r, FormatContext& ctx ) const -> FormatContext::iterator;

Equivalent to return underlying_.format(r, ctx);.

Returns an iterator past the end of the output range.

[edit] See also

defines formatting rules for a given type
(class template) [edit]
class template that helps implementing std::formatter specializations for range types
(class template) [edit]