std::vformat_to(3)

NAME
std::vformat_to - std::vformat_to

Synopsis
   Defined in header <format>
   template< class OutputIt >
   OutputIt vformat_to( OutputIt out, std::string_view fmt, (1) (since C++20)
   std::format_args args );
   template< class OutputIt >
   OutputIt vformat_to( OutputIt out, std::wstring_view fmt, (2) (since C++20)
   std::wformat_args args );
   template< class OutputIt >
   OutputIt vformat_to( OutputIt out, const std::locale& loc, (3) (since C++20)
                        std::string_view fmt, std::format_args args
   );
   template< class OutputIt >
   OutputIt vformat_to( OutputIt out, const std::locale& loc, (4) (since C++20)
                        std::wstring_view fmt, std::wformat_args args
   );
   Format arguments held by args according to the format string fmt, and write the
   result to the output iterator out. If present, loc is used for locale-specific
   formatting.
   Let CharT be decltype(fmt)::char_type (char for overloads (1,3), wchar_t for
   overloads (2,4)).
   These overloads participate in overload resolution only if OutputIt satisfies the
   concept std::output_iterator<const CharT&>.
   The behavior is undefined if OutputIt does not model (meet the semantic requirements
   of) the concept std::output_iterator<const CharT&>, or if std::formatter<Ti, CharT>
   does not meet the Formatter requirements for any Ti in the type of arguments.

Parameters
   out - iterator to the output buffer
          an object that represents the format string. The format string consists of
            * ordinary characters (except { and }), which are copied unchanged to the
              output,
            * escape sequences {{ and }}, which are replaced with { and } respectively
              in the output, and
            * replacement fields.
          Each replacement field has the following format:
          { arg-id (optional) } (1)
          { arg-id (optional) : format-spec } (2)
          1) replacement field without a format specification
          2) replacement field with a format specification
                        specifies the index of the argument in args whose value is to
                        be used for formatting; if it is omitted, the arguments are
          arg-id - used in order.
                        The arg-id s in a format string must all be present or all be
                        omitted. Mixing manual and automatic indexing is an error.
   fmt - the format specification defined by the std::formatter
          format-spec - specialization for the corresponding argument. Cannot start
                        with }.
            * For basic types and standard string types, the format specification is
              interpreted as standard format specification.
            * For chrono types, the format specification is interpreted as chrono
              format specification.
            * For range types, the format specification is interpreted as
              range format specification.
            * For std::pair and std::tuple, the format specification is
              interpreted as tuple format specification. (since C++23)
            * For std::thread::id and std::stacktrace_entry, see thread
              id format specification and stacktrace entry format
              specification.
            * For std::basic_stacktrace, no format specifier is allowed.
            * For std::filesystem::path, see path format specification. (since C++26)
            * For other formattable types, the format specification is determined by
              user-defined formatter specializations.
   args - arguments to be formatted
   loc - std::locale used for locale-specific formatting

Return value
   Iterator past the end of the output range.

Exceptions
   Throws std::format_error if fmt is not a valid format string for the provided
   arguments. Also propagates any exception thrown by formatter or iterator operations.

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
   P2216R3 C++20 type of args is parameterized on OutputIt not parameterized

See also

Category:
     * Todo no example