std::atomic_flag_test, std::atomic_flag_test_explicit

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Atomic operations library

Types

atomic (C++11)

atomic_ref (C++20)

Functions

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)

Atomic flags

atomic_flag (C++11)

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)

Initialization

atomic_init (C++11)(deprecated in C++20)

ATOMIC_VAR_INIT (C++11)(deprecated in C++20)

ATOMIC_FLAG_INIT (C++11)(deprecated in C++20)

Memory ordering

memory_order (C++11)

kill_dependency (C++11)

atomic_thread_fence (C++11)

atomic_signal_fence (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.

See also

test (C++20)

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