Checks if the future refers to a shared state.

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

The behavior is undefined if any member function other than the destructor, the copy-assignment operator, the move-assignment operator, orvalid is called on ashared_future that does not refer to shared state (although implementations are encouraged to throwstd::future_error indicatingno_state in this case). It is valid to move or copy from a shared_future object for whichvalid() isfalse.

[edit]Parameters

(none)

[edit]Return value

true if*this refers to a shared state, otherwisefalse.

[edit]Example

#include <future>#include <iostream> int main(){std::promise<void> p;std::shared_future<void> f= p.get_future(); std::cout<<std::boolalpha; std::cout<< f.valid()<<'\n';    p.set_value();std::cout<< f.valid()<<'\n';    f.get();std::cout<< f.valid()<<'\n';}

truetruetrue

[edit]See also

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