# std::coroutine_handle<Promise>::coroutine_handle

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< cpp‎ | coroutine‎ | coroutine handle

constexpr coroutine_handle() noexcept; | (1) | (since C++20)
constexpr coroutine_handle( std::nullptr_t ) noexcept; | (2) | (since C++20)
coroutine_handle( const coroutine_handle& other ) = default; | (3) | (since C++20)
coroutine_handle( coroutine_handle&& other ) = default; | (4) | (since C++20)

Creates a `coroutine_handle` that does not refer a coroutine, or copies a `coroutine_handle`.

1-2) Initializes the underlying address to nullptr. After construction, address() returns nullptr, and the `coroutine_handle` does not refer a coroutine. These constructors are not declared for the specialization std::coroutine_handle<std::noop_coroutine_promise>.
3-4) Copies the underlying address. The copy constructor and move constructor are equivalent to implicitly declared ones.

### Parameters

other | - | another `coroutine_handle` to copy

### Notes

std::coroutine_handle<std::noop_coroutine_promise> is neither default constructible nor constructible from std::nullptr_t. std::noop_coroutine can be used to create a new std::coroutine_handle<std::noop_coroutine_promise>.

Static member functions from_promise and from_address can also create a `coroutine_handle`.

### See also

from_promise [static] (C++20) | creates a `coroutine_handle` from the promise object of a coroutine (public static member function)
from_address [static] (C++20) | imports a coroutine from a pointer (public static member function)
noop_coroutine (C++20) | creates a coroutine handle that has no observable effects when resumed or destroyed (function)

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