std::future_error (3) Linux Manual Page

std::future_error – std::future_error

Synopsis

Defined in header <future>
class future_error; (since C++11)
The class std::future_error defines an exception object that is thrown on failure by the functions in the thread library that deal with asynchronous execution and shared states (std::future, std::promise, etc). Similar to std::system_error, this exception carries an error code compatible with std::error_code.
 std-future error-inheritance.svg
Inheritance diagram

Member functions

              creates a std::future_error object
constructor (public member function)
              returns the error code
code (public member function)
              returns the explanatory string specific to the error code
what (public member function)

Inherited from std::logic_error

Inherited from std::exception

Member functions

destructor destroys the exception object
             (virtual public member function of std::exception)
[virtual]

what returns an explanatory string
             (virtual public member function of std::exception)
[virtual]

Example

// Run this code

#include <future>

#include <iostream>
int main()

{
    std::future<int> empty;
    try {
        int n = empty.get(); // The behavior is undefined, but
                             // some implementations throw std::future_error
    } catch (const std::future_error &e) {
        std::cout << "Caught a future_error with code \"" << e.code()
                  << "\"\nMessage: \"" << e.what() << "\"\n";
    }
}

Possible output:

  Caught a future_error with code "future:3"
  Message: "No associated state"

See also

future_errc identifies the future error codes
            (enum)
(C++11)