std::basic_format_args
Defined in header <format> |
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(1) | (since C++20) |
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(2) | (since C++20) |
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(3) | (since C++20) |
Provides access to formatting arguments.
Member functions
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(constructor)
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constructs a basic_format_args object (public member function) |
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get
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returns formatting argument at the given index (public member function) |
std::basic_format_args::basic_format_args
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(1) | |
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(2) |
1) Constructs a
basic_format_args object that does not hold any formatting argument.
2) 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 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).
std::basic_format_args::get
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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 object).
Deduction guides
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(since C++20) |
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 |
| LWG3810 | C++20 | basic_format_args has no deduction guide |
added |
See also
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(C++20)
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class template that provides access to a formatting argument for user-defined formatters (class template) |
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