table of contents
std::vformat_to(3) | C++ Standard Libary | 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
string view representing 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
fmt -
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-ids 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.
* 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 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¶
2022.07.31 | http://cppreference.com |