std::nullopt

 

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std::optional

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optional::optional

optional::~optional

optional::operator=

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optional::operator->optional::operator*

optional::operator booloptional::has_value

optional::value

optional::value_or

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optional::begin (C++26)

optional::end (C++26)

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optional::and_then (C++23)

optional::transform (C++23)

optional::or_else (C++23)

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optional::emplace

optional::swap

optional::reset

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

make_optional

swap(std::optional)

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hash<std::optional>

nullopt_t

in_place_t

bad_optional_access

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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. Used to indicate that an std::optional does not contain a value.

See also

nullopt_t (C++17)

indicator of an std::optional that does not contain a value (class)