std::vformat_to

 

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Formatting library

Standard format specification

Formatting functions

format (C++20)

format_to (C++20)

format_to_n (C++20)

formatted_size (C++20)

vformat (C++20)

vformat_to (C++20)

Format strings

basic_format_stringformat_stringwformat_string (C++20)(C++20)(C++20)

runtime_format (C++26)

Formatting concepts

formattable (C++23)

Formatter

formatter (C++20)

formatter<pair-or-tuple> (C++23)

formatter<range> (C++23)

range_formatter (C++23)

enable_nonlocking_formatter_optimization (C++23)

basic_format_parse_contextformat_parse_contextwformat_parse_context (C++20)(C++20)(C++20)

basic_format_contextformat_contextwformat_context (C++20)(C++20)(C++20)

range_format (C++23)

format_kind (C++23)

Formatting arguments

basic_format_arg (C++20)

basic_format_arg::handle (C++20)

basic_format_argsformat_argswformat_args (C++20)(C++20)(C++20)

visit_format_arg (C++20) (deprecated in C++26)

make_format_argsmake_wformat_args (C++20)(C++20)

Format error

format_error (C++20)

 

Defined in header <format>
template<class OutputIt> OutputIt vformat_to(OutputIt out,                     std::string_view fmt,                     std::format_args_t<std::type_identity_t<OutputIt>, char> args);	(1)	(since C++20)
template<class OutputIt, class... Args> OutputIt vformat_to(OutputIt out,                     std::wstring_view fmt,                     std::format_args_t<std::type_identity_t<OutputIt>, wchar_t> args);	(2)	(since C++20)
template<class OutputIt, class... Args> OutputIt vformat_to(OutputIt out, const std::locale& loc,                     std::string_view fmt,                       std::format_args_t<std::type_identity_t<OutputIt>, char> args);	(3)	(since C++20)
template<class OutputIt, class... Args> OutputIt vformat_to(OutputIt out, const std::locale& loc,                     std::wstring_view fmt,                       std::format_args_t<std::type_identity_t<OutputIt>, wchar_t> args);	(4)	(since C++20)

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 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
fmt	-	string view representing the format string. 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 arg-id - specifies the index of the argument in args whose value is to be used for formatting; if it is omitted, the arguments are 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. format-spec - the format specification defined by the std::formatter 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. 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. (since C++23) 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.