std::atomic<T>::atomic

 

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

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

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)

 

std::atomic

Member functions

atomic::atomic

atomic::operator=

atomic::is_lock_free

atomic::store

atomic::load

atomic::operator T

atomic::exchange

atomic::compare_exchange_strongatomic::compare_exchange_weak

atomic::wait (C++20)

atomic::notify_one (C++20)

atomic::notify_all (C++20)

Constants

atomic::is_always_lock_free (C++17)

Specialized member functions

atomic::fetch_add

atomic::fetch_sub

atomic::fetch_and

atomic::fetch_or

atomic::fetch_xor

atomic::operator++atomic::operator++(int)atomic::operator--atomic::operator--(int)

atomic::operator+=atomic::operator-=atomic::operator&=atomic::operator|=atomic::operator^=

 

	(1)
atomic() noexcept = default;			(since C++11) (until C++20)
constexpr atomic() noexcept(std::is_nothrow_default_constructible_v<T>);			(since C++20)
constexpr atomic( T desired ) noexcept;		(2)	(since C++11)
atomic( const atomic& ) = delete;		(3)	(since C++11)

Constructs new atomic variable.

1) The default constructor is trivial: no initialization takes place other than zero initialization of static and thread-local objects. std::atomic_init may be used to complete initialization.	(until C++20)
1) Value-initializes the underlying object (i.e. with T()). The initialization is not atomic. Use of the default constructor is ill-formed if std::is_default_constructible_v<T> is false.	(since C++20)

2) Initializes the underlying object with desired. The initialization is not atomic.

3) Atomic variables are not CopyConstructible.

Parameters

desired

-

value to initialize with

Notes

The default-initialized std::atomic<T> does not contain a T object, and its only valid uses are destruction and initialization by std::atomic_init, see LWG 2334

(until C++20)