std::basic_format_context(3)

NAME
std::basic_format_context - std::basic_format_context

Synopsis
   Defined in header <format>
   template<class OutputIt, class CharT> (1) (since C++20)
   class basic_format_context;
   using format_context = basic_format_context</* unspecified */, (2) (since C++20)
   char>;
   using wformat_context = basic_format_context</* unspecified */, (3) (since C++20)
   wchar_t>;
   Provides access to formatting state consisting of the formatting arguments and the
   output iterator.
   The behavior is undefined if OutputIt does not model std::output_iterator<const
   CharT&>.
   2) The unspecified template argument is an output iterator that appends to
   std::string, such as std::back_insert_iterator<std::string>. Implementations are
   encouraged to use an iterator to type-erased buffer type that supports appending to
   any contiguous and resizable container.
   3) The unspecified template argument is an output iterator that appends to
   std::wstring.

Member types
   Type Definition
   iterator OutputIt
   char_type CharT

Member alias templates
   Type Definition
   formatter_type<T> std::formatter<T, CharT>

Member functions
   arg returns the argument at the given index
              (public member function)
   locale returns the locale used for locale-specific formatting
              (public member function)
   out returns the iterator to output buffer
              (public member function)
   advance_to advances the output iterator to the given position
              (public member function) std::basic_format_context::arg
   std::basic_format_arg<basic_format_context> arg( std::size_t id ) const;
   Returns a std::basic_format_arg holding the id-th argument in args, where args is
   the parameter pack or std::basic_format_args object passed to the formatting
   function.
   If id is not less than the number of formatting arguments, returns a
   default-constructed std::basic_format_arg (holding a std::monostate object). std::basic_format_context::locale
   std::locale locale();
   Returns the locale passed to the formatting function, or a default-constructed
   std::locale if the formatting function does not take a locale. std::basic_format_context::out
   iterator out();
   Returns the iterator to the output buffer. The result is move-constructed from the
   stored iterator. std::basic_format_context::advance_to
   void advance_to( iterator it );
   Move assigns it to the stored output iterator. After a call to advance_to, the next
   call to out() will return an iterator with the value that it had before the
   assignment.

Example
    This section is incomplete
    Reason: no example
  Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
      DR Applied to Behavior as published Correct behavior
   LWG 3567 C++20 basic_format_context does not work move-only made to move
                       iterator types iterators

See also