std::atomic_flag_test, std::atomic_flag_test_explicit

 

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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)

 

Defined in header <atomic>
	(1)	(since C++20)
bool atomic_flag_test( const volatile std::atomic_flag* object ) noexcept;
bool atomic_flag_test( const std::atomic_flag* object ) noexcept;
			(2)	(since C++20)
bool atomic_flag_test_explicit( const volatile std::atomic_flag* object,                                 std::memory_order order ) noexcept;
bool atomic_flag_test_explicit( const std::atomic_flag* object,                                 std::memory_order order ) noexcept;

Atomically reads the value of the *object and returns the value.

1) Equivalent to object->test(std::memory_order_seq_cst).

2) Equivalent to object->test(order).

Parameters

object	-	pointer to the atomic_flag object to read
order	-	the memory synchronization ordering for this operation: must not be std::memory_order::release or std::memory_order::acq_rel

Return value

The value atomically read.

Notes

Feature-test macro:

__cpp_lib_atomic_flag_test

See also

test (C++20)

atomically returns the value of the flag (public member function of std::atomic_flag)