std::in_place

 

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in_place

 

Defined in header <optional>
constexpr in_place_t in_place{};		(since C++17)

std::in_place is a constant of type std::in_place_t that is used to disambiguate the overloads of constructors and member functions of that take arguments (possibly a parameter pack) for in-place construction of some value.

See also

in_place_t (since C++17)	disambiguation tag type for in-place construction of optional types (class)
optional (since C++17)	a wrapper that may or may not hold an object (class template)