std::vformat_to
<format>
OutputIt vformat_to( OutputIt out, std::string_view fmt, std::format_args args );
OutputIt vformat_to( OutputIt out, std::wstring_view fmt, std::wformat_args args );
OutputIt vformat_to( OutputIt out, const std::locale & loc,
OutputIt vformat_to( OutputIt out, const std::locale & loc,
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&>.
OutputIt must model (meet the semantic requirements of) the concept std::output_iterator <const CharT&>, and std::formatter <Ti, CharT> must meet the Formatter requirements for any Ti in the type of arguments. Otherwise, the behavior is undefined.
[edit] Parameters
- 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)
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.
- 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.
- For other formattable types, the format specification is determined by user-defined
formatterspecializations.
[edit] Return value
Iterator past the end of the output range.
[edit] 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.
[edit] Example
Reason: no example
[edit] 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 |