atomic_exchange, atomic_exchange_explicit — atomically exchange the value of an object
#include <stdatomic.h>
C atomic_exchange(volatile A *object, C desired);
C atomic_exchange_explicit(volatile A *object, C desired,
memory_order order);
[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.Implementations that define the macro __STDC_NO_ATOMICS__ need not provide the <stdatomic.h> header nor support these generic functions.
The atomic_exchange_explicit() generic function shall atomically replace the value pointed to by object with desired. This operation shall be an atomic read-modify-write operation (see XBD 4.15.1 Memory Ordering ). Memory shall be affected according to the value of order.
The atomic_exchange() generic function shall be equivalent to atomic_exchange_explicit() called with order set to memory_order_seq_cst.
These generic functions shall return the value pointed to by object immediately before the effects.
No errors are defined.
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First released in Issue 8. Included for alignment with the ISO/IEC 9899:2018 standard.
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