20 General utilities library [utilities]

20.20 Formatting [format]

20.20.6 Arguments [format.arguments]

20.20.6.3 Class template basic_­format_­args [format.args]

namespace std { template<class Context> class basic_format_args { size_t size_; // exposition only const basic_format_arg<Context>* data_; // exposition only public: basic_format_args() noexcept; template<class... Args> basic_format_args(const format-arg-store<Context, Args...>& store) noexcept; basic_format_arg<Context> get(size_t i) const noexcept; }; }
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An instance of basic_­format_­args provides access to formatting arguments.
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basic_format_args() noexcept;
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Effects: Initializes size_­ with 0.
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template<class... Args> basic_format_args(const format-arg-store<Context, Args...>& store) noexcept;
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Effects: Initializes size_­ with sizeof...(Args) and data_­ with store.args.data().
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basic_format_arg<Context> get(size_t i) const noexcept;
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Returns: i < size_­ ? data_­[i] : basic_­format_­arg<Context>().
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[Note 1:
Implementations are encouraged to optimize the representation of basic_­format_­args for small number of formatting arguments by storing indices of type alternatives separately from values and packing the former.
— end note]