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std::basic_format_args

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< cpp‎ | utility‎ | format
 
 
Utilities library
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Formatting library
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Formatter
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Formatting arguments
basic_format_argsformat_argswformat_argsformat_args_t
(C++20)(C++20)(C++20)(C++20)
Format error
 
Defined in header <format>
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)
template<class OutputIt, class CharT>
using format_args_t = basic_format_args<std::basic_format_context<OutputIt, CharT>>;
(4) (since C++20)

Provides access to formatting arguments.

Contents

[edit] 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

basic_format_args() noexcept;
(1)
template<class... Args>
basic_format_args(const /*format-arg-store*/<Context, Args...>& store) noexcept;
(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

std::basic_format_arg<Context> get(std::size_t i) const noexcept;

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).

[edit] Example

[edit] See also

class template that provides access to a formatting argument for user-defined formatters
(class template) [edit]