Atomic operations library

If the macro constant __STDC_NO_ATOMICS__ (C11) is defined by the compiler, the header <stdatomic.h> , the keyword _Atomic , and all of the names listed here are not provided.

Types

Defined in header <stdatomic.h>
memory_order (C11)	defines memory ordering constraints (enum)
atomic_flag (C11)	lock-free atomic boolean flag (struct)

Macros

Defined in header <stdatomic.h>
ATOMIC_BOOL_LOCK_FREE ATOMIC_CHAR_LOCK_FREE ATOMIC_CHAR16_T_LOCK_FREE ATOMIC_CHAR32_T_LOCK_FREE ATOMIC_WCHAR_T_LOCK_FREE ATOMIC_SHORT_LOCK_FREE ATOMIC_INT_LOCK_FREE ATOMIC_LONG_LOCK_FREE ATOMIC_LLONG_LOCK_FREE ATOMIC_POINTER_LOCK_FREE (C11)	indicates that the given atomic type is lock-free (macro constant)
ATOMIC_FLAG_INIT (C11)	initializes a new atomic_flag (macro constant)
ATOMIC_VAR_INIT (C11) (deprecated in C17) (removed in C23)	initializes a new atomic object (function macro)
kill_dependency (C11)	breaks a dependency chain for memory_order_consume (function macro)

Functions

Defined in header <stdatomic.h>
atomic_flag_test_and_set atomic_flag_test_and_set_explicit (C11)	sets an atomic_flag to true and returns the old value (function)
atomic_flag_clear atomic_flag_clear_explicit (C11)	sets an atomic_flag to false (function)
atomic_init (C11)	initializes an existing atomic object (function)
atomic_is_lock_free (C11)	indicates whether the atomic object is lock-free (function)
atomic_store atomic_store_explicit (C11)	stores a value in an atomic object (function)
atomic_load atomic_load_explicit (C11)	reads a value from an atomic object (function)
atomic_exchange atomic_exchange_explicit (C11)	swaps a value with the value of an atomic object (function)
atomic_compare_exchange_strong atomic_compare_exchange_strong_explicit atomic_compare_exchange_weak atomic_compare_exchange_weak_explicit (C11)	swaps a value with an atomic object if the old value is what is expected, otherwise reads the old value (function)
atomic_fetch_add atomic_fetch_add_explicit (C11)	atomic addition (function)
atomic_fetch_sub atomic_fetch_sub_explicit (C11)	atomic subtraction (function)
atomic_fetch_or atomic_fetch_or_explicit (C11)	atomic bitwise OR (function)
atomic_fetch_xor atomic_fetch_xor_explicit (C11)	atomic bitwise exclusive OR (function)
atomic_fetch_and atomic_fetch_and_explicit (C11)	atomic bitwise AND (function)
atomic_thread_fence (C11)	generic memory order-dependent fence synchronization primitive (function)
atomic_signal_fence (C11)	fence between a thread and a signal handler executed in the same thread (function)

Types

The standard library offers convenience typedefs for the core language atomic types .

Typedef name	Full type name
atomic_bool	_Atomic _Bool
atomic_char	_Atomic char
atomic_schar	_Atomic signed char
atomic_uchar	_Atomic unsigned char
atomic_short	_Atomic short
atomic_ushort	_Atomic unsigned short
atomic_int	_Atomic int
atomic_uint	_Atomic unsigned int
atomic_long	_Atomic long
atomic_ulong	_Atomic unsigned long
atomic_llong	_Atomic long long
atomic_ullong	_Atomic unsigned long long
atomic_char8_t (C23)	_Atomic char8_t
atomic_char16_t	_Atomic char16_t
atomic_char32_t	_Atomic char32_t
atomic_wchar_t	_Atomic wchar_t
atomic_int_least8_t	_Atomic int_least8_t
atomic_uint_least8_t	_Atomic uint_least8_t
atomic_int_least16_t	_Atomic int_least16_t
atomic_uint_least16_t	_Atomic uint_least16_t
atomic_int_least32_t	_Atomic int_least32_t
atomic_uint_least32_t	_Atomic uint_least32_t
atomic_int_least64_t	_Atomic int_least64_t
atomic_uint_least64_t	_Atomic uint_least64_t
atomic_int_fast8_t	_Atomic int_fast8_t
atomic_uint_fast8_t	_Atomic uint_fast8_t
atomic_int_fast16_t	_Atomic int_fast16_t
atomic_uint_fast16_t	_Atomic uint_fast16_t
atomic_int_fast32_t	_Atomic int_fast32_t
atomic_uint_fast32_t	_Atomic uint_fast32_t
atomic_int_fast64_t	_Atomic int_fast64_t
atomic_uint_fast64_t	_Atomic uint_fast64_t
atomic_intptr_t	_Atomic intptr_t
atomic_uintptr_t	_Atomic uintptr_t
atomic_size_t	_Atomic size_t
atomic_ptrdiff_t	_Atomic ptrdiff_t
atomic_intmax_t	_Atomic intmax_t
atomic_uintmax_t	_Atomic uintmax_t

References

See also

C++ documentation for Atomic operations library