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std::experi...::nullopt_t(3)  C++ Standard Libary std::experi...::nullopt_t(3)

NAME
       std::experimental::nullopt_t - std::experimental::nullopt_t

Synopsis
	  Defined in header <experimental/optional>
	  struct nullopt_t;			     (library fundamentals TS)

	  std::experimental::nullopt_t is an empty class type used to indicate
       optional	type
	  with uninitialized state. In particular, std::experimental::optional
       has a
	  constructor  with  nullopt_t	as a single argument, which creates an
       optional	that does
	  not contain a	value.

	  std::experimental::nullopt_t must be a LiteralType and cannot	have a
       default
	  constructor.

	  It must have a constexpr constructor that takes some implementation-
       defined literal
	  type.

Notes
	  nullopt_t is not DefaultConstructible	to support both	op =  {};  and
       op = nullopt; as
	  the syntax for disengaging an	optional object.

	  A possible implementation of this class is

	struct nullopt_t {
	    constexpr nullopt_t(int) {}
	};

See also
	  nullopt an object of type nullopt_t
	  (C++17) (constant)

http://cppreference.com		  2022.07.31	  std::experi...::nullopt_t(3)

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