std::shared_future::valid

From cppreference.com
< cpplrm; | threadlrm; | shared future

Thread support library
Threads
(C++11)
this_thread namespace
(C++11)
(C++11)
(C++11)
Mutual exclusion
(C++11)
Generic lock management
(C++11)
(C++11)
(C++11)
(C++11)(C++11)(C++11)
(C++11)
(C++11)
Condition variables
(C++11)
Futures
(C++11)
(C++11)
(C++11)
(C++11)
bool valid() const noexcept;
(since C++11)

Checks if the future refers to a shared state.

This is the case only for futures that were not default-constructed or moved from. Unlike std::future, std::shared_future's shared state is not invalidated when get() is called.

The behavior is undefined if any member function other than the destructor, the copy-assignment operator, the move-assignment operator, or valid is called on a shared_future that does not refer to shared state (although implementations are encouraged to throw std::future_error indicating no_state in this case). It is valid to move or copy from a shared_future object for which valid() is false

Parameters

(none)

Return value

true if *this refers to a shared state, otherwise false.

Example

See also

waits for the result to become available
(public member function)