std::future_error

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Concurrency support library

Threads thread (C++11) jthread (C++20) stop_token (C++20) stop_source (C++20) stop_callback (C++20) hardware_destructive_interference_sizehardware_constructive_interference_size (C++17)(C++17)     this_thread namespace get_id (C++11) yield (C++11) sleep_for (C++11) sleep_until (C++11) Atomic types atomic (C++11) atomic_ref (C++20) atomic_flag (C++11) Initialization of atomic types atomic_init (C++11)(deprecated in C++20) ATOMIC_VAR_INIT (C++11)(deprecated in C++20) ATOMIC_FLAG_INIT (C++11) Free functions for atomic operations atomic_storeatomic_store_explicit (C++11)(C++11) atomic_loadatomic_load_explicit (C++11)(C++11) atomic_exchangeatomic_exchange_explicit (C++11)(C++11) atomic_compare_exchange_weakatomic_compare_exchange_weak_explicitatomic_compare_exchange_strongatomic_compare_exchange_strong_explicit (C++11)(C++11)(C++11)(C++11) atomic_fetch_addatomic_fetch_add_explicit (C++11)(C++11) atomic_fetch_subatomic_fetch_sub_explicit (C++11)(C++11) atomic_fetch_andatomic_fetch_and_explicit (C++11)(C++11) atomic_fetch_oratomic_fetch_or_explicit (C++11)(C++11) atomic_fetch_xoratomic_fetch_xor_explicit (C++11)(C++11) atomic_is_lock_free (C++11) atomic_waitatomic_wait_explicit (C++20)(C++20) atomic_notify_one (C++20) atomic_notify_all (C++20)

Free functions for atomic flags atomic_flag_test_and_setatomic_flag_test_and_set_explicit (C++11)(C++11) atomic_flag_clearatomic_flag_clear_explicit (C++11)(C++11) atomic_flag_testatomic_flag_test_explicit (C++20)(C++20) atomic_flag_waitatomic_flag_wait_explicit (C++20)(C++20) atomic_flag_notify_one (C++20) atomic_flag_notify_all (C++20) Memory ordering memory_order (C++11) kill_dependency (C++11) atomic_thread_fence (C++11) atomic_signal_fence (C++11) Mutual exclusion mutex (C++11) recursive_mutex (C++11) shared_mutex (C++17) timed_mutex (C++11) recursive_timed_mutex (C++11) shared_timed_mutex (C++14) Generic lock management lock_guard (C++11) scoped_lock (C++17) unique_lock (C++11) shared_lock (C++14) defer_lock_ttry_to_lock_tadopt_lock_t (C++11)(C++11)(C++11) lock (C++11) try_lock (C++11) defer_locktry_to_lockadopt_lock (C++11)(C++11)(C++11) once_flag (C++11) call_once (C++11) Condition variables condition_variable (C++11) condition_variable_any (C++11) notify_all_at_thread_exit (C++11) cv_status (C++11) Semaphores counting_semaphorebinary_semaphore (C++20)(C++20) Latches and barriers latch (C++20) barrier (C++20) Futures promise (C++11) future (C++11) shared_future (C++11) packaged_task (C++11) async (C++11) launch (C++11) future_status (C++11) future_error (C++11) future_category (C++11) future_errc (C++11)

 

std::future_error

Member functions

future_error::future_error

future_error::operator=

future_error::code

future_error::what

 

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.

Inheritance diagram

Member functions

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

Inherited from std::logic_error

Inherited from std::exception

Member functions

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

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 (C++11)

identifies the future error codes (enum)