std::nullopt

 

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std::optional

Member functions

optional::optional

optional::~optional

optional::operator=

Observers

optional::operator->optional::operator*

optional::operator booloptional::has_value

optional::value

optional::value_or

Modifiers

optional::emplace

optional::swap

optional::reset

Non-member functions

operator==operator!=operator<operator<=operator>operator>=operator<=> (C++20)

make_optional

swap

Deduction guides

Helper classes

hash

nullopt_t

in_place_t

bad_optional_access

Helper objects

nullopt

in_place

 

Defined in header <optional>
inline constexpr nullopt_t nullopt{/*unspecified*/};		(since C++17)

std::nullopt is a constant of type std::nullopt_t that is used to indicate optional type with uninitialized state.

See also

nullopt_t (C++17)

indicator of optional type with uninitialized state (class)