std::shared_future::valid

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bool valid() const;
(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.

Exceptions

noexcept specification:  
noexcept
  

Example

See also

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