Standard library header <stdatomic.h>

 

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Standard library headers

Language support <cfloat> <climits> <compare> (C++20) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) Concepts <concepts> (C++20) Diagnostics <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) Memory management <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) Metaprogramming <type_traits> (C++11) <ratio> (C++11)

General utilities <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) Containers <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> Iterators <iterator> Ranges <generator> (C++23) <ranges> (C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> Text processing <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    Numerics <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <valarray> Time <chrono> (C++11) <ctime> C compatibility <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

Input/output <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) Concurrency support <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) Execution support <execution> (C++17)

 

This header was originally in the C standard library.

This header is part of the concurrency support library.

It is unspecified whether <stdatomic.h> provides any declarations in namespace std.

Macros
_Atomic (C++23)	compatibility macro such that _Atomic(T) is identical to std::atomic<T> (function macro)
ATOMIC_FLAG_INIT (C++11)	initializes an std::atomic_flag to false (macro constant)
Types
atomic_flag (C++11)	the lock-free boolean atomic type (class)
memory_order (C++11)	defines memory ordering constraints for the given atomic operation (enum)
atomic_bool (C++11)	std::atomic<bool> (typedef)
atomic_char (C++11)	std::atomic<char> (typedef)
atomic_schar (C++11)	std::atomic<signed char> (typedef)
atomic_uchar (C++11)	std::atomic<unsigned char> (typedef)
atomic_short (C++11)	std::atomic<short> (typedef)
atomic_ushort (C++11)	std::atomic<unsigned short> (typedef)
atomic_int (C++11)	std::atomic<int> (typedef)
atomic_uint (C++11)	std::atomic<unsigned int> (typedef)
atomic_long (C++11)	std::atomic<long> (typedef)
atomic_ulong (C++11)	std::atomic<unsigned long> (typedef)
atomic_llong (C++11)	std::atomic<long long> (typedef)
atomic_ullong (C++11)	std::atomic<unsigned long long> (typedef)
atomic_char8_t (C++20)	std::atomic<char8_t> (typedef)
atomic_char16_t (C++11)	std::atomic<char16_t> (typedef)
atomic_char32_t (C++11)	std::atomic<char32_t> (typedef)
atomic_wchar_t (C++11)	std::atomic<wchar_t> (typedef)
atomic_int8_t (C++11)(optional)	std::atomic<std::int8_t> (typedef)
atomic_uint8_t (C++11)(optional)	std::atomic<std::uint8_t> (typedef)
atomic_int16_t (C++11)(optional)	std::atomic<std::int16_t> (typedef)
atomic_uint16_t (C++11)(optional)	std::atomic<std::uint16_t> (typedef)
atomic_int32_t (C++11)(optional)	std::atomic<std::int32_t> (typedef)
atomic_uint32_t (C++11)(optional)	std::atomic<std::uint32_t> (typedef)
atomic_int64_t (C++11)(optional)	std::atomic<std::int64_t> (typedef)
atomic_uint64_t (C++11)(optional)	std::atomic<std::uint64_t> (typedef)
atomic_int_least8_t (C++11)	std::atomic<std::int_least8_t> (typedef)
atomic_uint_least8_t (C++11)	std::atomic<std::uint_least8_t> (typedef)
atomic_int_least16_t (C++11)	std::atomic<std::int_least16_t> (typedef)
atomic_uint_least16_t (C++11)	std::atomic<std::uint_least16_t> (typedef)
atomic_int_least32_t (C++11)	std::atomic<std::int_least32_t> (typedef)
atomic_uint_least32_t (C++11)	std::atomic<std::uint_least32_t> (typedef)
atomic_int_least64_t (C++11)	std::atomic<std::int_least64_t> (typedef)
atomic_uint_least64_t (C++11)	std::atomic<std::uint_least64_t> (typedef)
atomic_int_fast8_t (C++11)	std::atomic<std::int_fast8_t> (typedef)
atomic_uint_fast8_t (C++11)	std::atomic<std::uint_fast8_t> (typedef)
atomic_int_fast16_t (C++11)	std::atomic<std::int_fast16_t> (typedef)
atomic_uint_fast16_t (C++11)	std::atomic<std::uint_fast16_t> (typedef)
atomic_int_fast32_t (C++11)	std::atomic<std::int_fast32_t> (typedef)
atomic_uint_fast32_t (C++11)	std::atomic<std::uint_fast32_t> (typedef)
atomic_int_fast64_t (C++11)	std::atomic<std::int_fast64_t> (typedef)
atomic_uint_fast64_t (C++11)	std::atomic<std::uint_fast64_t> (typedef)
atomic_intptr_t (C++11)(optional)	std::atomic<std::intptr_t> (typedef)
atomic_uintptr_t (C++11)(optional)	std::atomic<std::uintptr_t> (typedef)
atomic_size_t (C++11)	std::atomic<std::size_t> (typedef)
atomic_ptrdiff_t (C++11)	std::atomic<std::ptrdiff_t> (typedef)
atomic_intmax_t (C++11)	std::atomic<std::intmax_t> (typedef)
atomic_uintmax_t (C++11)	std::atomic<std::uintmax_t> (typedef)
Functions
atomic_is_lock_free (C++11)	checks if the atomic type's operations are lock-free (function template)
atomic_storeatomic_store_explicit (C++11)(C++11)	atomically replaces the value of the atomic object with a non-atomic argument (function template)
atomic_loadatomic_load_explicit (C++11)(C++11)	atomically obtains the value stored in an atomic object (function template)
atomic_exchangeatomic_exchange_explicit (C++11)(C++11)	atomically replaces the value of the atomic object with non-atomic argument and returns the old value of the atomic (function template)
atomic_compare_exchange_weakatomic_compare_exchange_weak_explicitatomic_compare_exchange_strongatomic_compare_exchange_strong_explicit (C++11)(C++11)(C++11)(C++11)	atomically compares the value of the atomic object with non-atomic argument and performs atomic exchange if equal or atomic load if not (function template)
atomic_fetch_addatomic_fetch_add_explicit (C++11)(C++11)	adds a non-atomic value to an atomic object and obtains the previous value of the atomic (function template)
atomic_fetch_subatomic_fetch_sub_explicit (C++11)(C++11)	subtracts a non-atomic value from an atomic object and obtains the previous value of the atomic (function template)
atomic_fetch_andatomic_fetch_and_explicit (C++11)(C++11)	replaces the atomic object with the result of bitwise AND with a non-atomic argument and obtains the previous value of the atomic (function template)
atomic_fetch_oratomic_fetch_or_explicit (C++11)(C++11)	replaces the atomic object with the result of bitwise OR with a non-atomic argument and obtains the previous value of the atomic (function template)
atomic_fetch_xoratomic_fetch_xor_explicit (C++11)(C++11)	replaces the atomic object with the result of bitwise XOR with a non-atomic argument and obtains the previous value of the atomic (function template)
atomic_flag_test_and_setatomic_flag_test_and_set_explicit (C++11)(C++11)	atomically sets the flag to true and returns its previous value (function)
atomic_flag_clearatomic_flag_clear_explicit (C++11)(C++11)	atomically sets the value of the flag to false (function)
atomic_thread_fence (C++11)	generic memory order-dependent fence synchronization primitive (function)
atomic_signal_fence (C++11)	fence between a thread and a signal handler executed in the same thread (function)

Synopsis

template<class T>
  using __std_atomic = std::atomic<T>;        // exposition only
 
#define _Atomic(T) __std_atomic<T>
 
#define ATOMIC_BOOL_LOCK_FREE /* see description */
#define ATOMIC_CHAR_LOCK_FREE /* see description */
#define ATOMIC_CHAR16_T_LOCK_FREE /* see description */
#define ATOMIC_CHAR32_T_LOCK_FREE /* see description */
#define ATOMIC_WCHAR_T_LOCK_FREE /* see description */
#define ATOMIC_SHORT_LOCK_FREE /* see description */
#define ATOMIC_INT_LOCK_FREE /* see description */
#define ATOMIC_LONG_LOCK_FREE /* see description */
#define ATOMIC_LLONG_LOCK_FREE /* see description */
#define ATOMIC_POINTER_LOCK_FREE /* see description */
 
using std::memory_order;                // see description
using std::memory_order_relaxed;        // see description
using std::memory_order_consume;        // see description
using std::memory_order_acquire;        // see description
using std::memory_order_release;        // see description
using std::memory_order_acq_rel;        // see description
using std::memory_order_seq_cst;        // see description
 
using std::atomic_flag;                 // see description
 
using std::atomic_bool;                 // see description
using std::atomic_char;                 // see description
using std::atomic_schar;                // see description
using std::atomic_uchar;                // see description
using std::atomic_short;                // see description
using std::atomic_ushort;               // see description
using std::atomic_int;                  // see description
using std::atomic_uint;                 // see description
using std::atomic_long;                 // see description
using std::atomic_ulong;                // see description
using std::atomic_llong;                // see description
using std::atomic_ullong;               // see description
using std::atomic_char8_t;              // see description
using std::atomic_char16_t;             // see description
using std::atomic_char32_t;             // see description
using std::atomic_wchar_t;              // see description
using std::atomic_int8_t;               // see description
using std::atomic_uint8_t;              // see description
using std::atomic_int16_t;              // see description
using std::atomic_uint16_t;             // see description
using std::atomic_int32_t;              // see description
using std::atomic_uint32_t;             // see description
using std::atomic_int64_t;              // see description
using std::atomic_uint64_t;             // see description
using std::atomic_int_least8_t;         // see description
using std::atomic_uint_least8_t;        // see description
using std::atomic_int_least16_t;        // see description
using std::atomic_uint_least16_t;       // see description
using std::atomic_int_least32_t;        // see description
using std::atomic_uint_least32_t;       // see description
using std::atomic_int_least64_t;        // see description
using std::atomic_uint_least64_t;       // see description
using std::atomic_int_fast8_t;          // see description
using std::atomic_uint_fast8_t;         // see description
using std::atomic_int_fast16_t;         // see description
using std::atomic_uint_fast16_t;        // see description
using std::atomic_int_fast32_t;         // see description
using std::atomic_uint_fast32_t;        // see description
using std::atomic_int_fast64_t;         // see description
using std::atomic_uint_fast64_t;        // see description
using std::atomic_intptr_t;             // see description
using std::atomic_uintptr_t;            // see description
using std::atomic_size_t;               // see description
using std::atomic_ptrdiff_t;            // see description
using std::atomic_intmax_t;             // see description
using std::atomic_uintmax_t;            // see description
 
using std::atomic_is_lock_free;                         // see description
using std::atomic_load;                                 // see description
using std::atomic_load_explicit;                        // see description
using std::atomic_store;                                // see description
using std::atomic_store_explicit;                       // see description
using std::atomic_exchange;                             // see description
using std::atomic_exchange_explicit;                    // see description
using std::atomic_compare_exchange_strong;              // see description
using std::atomic_compare_exchange_strong_explicit;     // see description
using std::atomic_compare_exchange_weak;                // see description
using std::atomic_compare_exchange_weak_explicit;       // see description
using std::atomic_fetch_add;                            // see description
using std::atomic_fetch_add_explicit;                   // see description
using std::atomic_fetch_sub;                            // see description
using std::atomic_fetch_sub_explicit;                   // see description
using std::atomic_fetch_or;                             // see description
using std::atomic_fetch_or_explicit;                    // see description
using std::atomic_fetch_xor;                            // see description
using std::atomic_fetch_xor_explicit;                   // see description
using std::atomic_fetch_and;                            // see description
using std::atomic_fetch_and_explicit;                   // see description
using std::atomic_flag_test_and_set;                    // see description
using std::atomic_flag_test_and_set_explicit;           // see description
using std::atomic_flag_clear;                           // see description
using std::atomic_flag_clear_explicit;                  // see description
 
#define ATOMIC_FLAG_INIT /* see description */
 
using std::atomic_thread_fence;                         // see description
using std::atomic_signal_fence;                         // see description