NAME

std::vformat - std::vformat

Synopsis

Defined in header <format>
std::string vformat(std::string_view fmt, std::format_args args); (1) (since C++20)
std::wstring vformat(std::wstring_view fmt, std::wformat_args (2) (since C++20)
args);
std::string vformat(const std::locale& loc, std::string_view fmt, (3) (since C++20)
std::format_args args);
std::wstring vformat(const std::locale& loc, std::wstring_view (4) (since C++20)
fmt, std::wformat_args args);

Format arguments held by args according to the format string fmt, and return the
result as a string. If present, loc is used for locale-specific formatting.

Parameters

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

A string object holding the formatted result.

Exceptions

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

Example