std::basic_format_args - cppreference.com (original) (raw)
| Defined in header | ||
|---|---|---|
| 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.
Contents
[edit] Member functions
| | constructs a basic_format_args object (public member function) | | -------------------------------------------------------------------------- | | | 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; | | | | ----------------------------------------------------------------------------------------------------------------- | | |
Constructs a basic_format_args object from the result of a call to std::make_format_args or std::make_wformat_args.
[edit] Deduction guides
| template< class Context, class... Args >basic_format_args( /*format-arg-store*/<Context, Args...> ) -> basic_format_args<Context>; | | (since C++20) | | --------------------------------------------------------------------------------------------------------------------------------------------- | | ------------- |
[edit] 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).
[edit] 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 | 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 |
[edit] See also
| | class template that provides access to a formatting argument for user-defined formatters (class template) [edit] | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |