std::optional<T>::optional
From cppreference.com
constexpr optional() noexcept; |
(1) | (since C++17) |
constexpr optional( std::nullopt_t ) noexcept; |
(2) | (since C++17) |
constexpr optional( const optional& other ); |
(3) | (since C++17) |
constexpr optional( optional&& other ) noexcept(/* see below */); |
(4) | (since C++17) |
template< class U > optional( const optional<U>& other ); |
(5) | (since C++17) (constexpr since C++20) (conditionally explicit) |
template< class U > optional( optional<U>&& other ); |
(6) | (since C++17) (constexpr since C++20) (conditionally explicit) |
template< class... Args > constexpr explicit optional( std::in_place_t, Args&&... args ); |
(7) | (since C++17) |
template< class U, class... Args > constexpr explicit optional( std::in_place_t, |
(8) | (since C++17) |
template< class U = std::remove_cv_t<T> > constexpr optional( U&& value ); |
(9) | (since C++17) (conditionally explicit) |
Constructs a new optional object.
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