std::basic_format_args
Defined in header <format>
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||
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template
<
class Context >
class basic_format_args; |
(1) | (since C++20) |
|
using format_args = basic_format_args<
std::format_context
>
;
|
(2) | (since C++20) |
|
using wformat_args = basic_format_args<
std::wformat_context
>
;
|
(3) | (since C++20) |
Provides access to formatting arguments.
Member functions
(constructor) |
constructs a basic_format_args object (public member function) |
get |
returns formatting argument at the given index (public member function) |
std::basic_format_args::basic_format_args
|
template
<
class... Args
>
basic_format_args( const /*format-arg-store*/ <Context, Args...> & store ) noexcept ; |
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Constructs a basic_format_args object from the result of a call to std::make_format_args or std::make_wformat_args
std::basic_format_args::get
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std::basic_format_arg
<Context> get(
std::size_t i )
const
noexcept
;
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Returns a std::basic_format_arg holding the i-th argument in args, where args is the parameter pack passed to std::make_format_args or std::make_wformat_args
If there's no such formatting argument (i.e. *this was default-constructed or i is not less than the number of formatting arguments), returns a default-constructed std::basic_format_arg (holding a std::monostate
Deduction guides
|
template
<
class Context, class... Args
>
basic_format_args( /*format-arg-store*/ <Context, Args...> ) - > basic_format_args<Context> ; |
(since C++20) | |
Notes
std::basic_format_args has reference semantics. It is the programmer's responsibility to ensure that *this does not outlive store (which, in turn, should not outlive the arguments to std::make_format_args or std::make_wformat_args
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 | format_args_t was provided due to overparameterization of vformat_to
|
removed |
| LWG 3810 | C++20 | basic_format_args has no deduction guide
|
added |
| LWG 4106 | C++20 | basic_format_args was default-constructible
|
default constructor removed |
See also
|
(C++20)
|
class template that provides access to a formatting argument for user-defined formatters (class template) |