std::nullopt

 

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std::optional

Member functions

optional::optional (C++17)

optional::~optional (C++17)

optional::operator= (C++17)

Observers

optional::operator->optional::operator* (C++17)(C++17)

optional::operator booloptional::has_value (C++17)(C++17)

optional::value (C++17)

optional::value_or (C++17)

Monadic operations

optional::and_then (C++23)

optional::transform (C++23)

optional::or_else (C++23)

Modifiers

optional::emplace (C++17)

optional::swap (C++17)

optional::reset (C++17)

Non-member functions

operator==operator!=operator<operator<=operator>operator>=operator<=> (C++17)(C++17)(C++17)(C++17)(C++17)(C++17)(C++20)

make_optional (C++17)

swap (C++17)

Deduction guides

Helper classes

hash (C++17)

nullopt_t (C++17)

in_place_t (C++17)

bad_optional_access (C++17)

Helper objects

nullopt (C++17)

in_place (C++17)

 

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)