std::atomic<T>::exchange

		(since C++11)
T exchange( T desired, std::memory_order order = std::memory_order_seq_cst ) noexcept;
T exchange( T desired, std::memory_order order = std::memory_order_seq_cst ) volatile noexcept;

Atomically replaces the underlying value with desired. The operation is read-modify-write operation. Memory is affected according to the value of order.

The volatile-qualified version is deprecated if std::atomic<T>::is_always_lock_free is false.

(since C++20)

Parameters

desired	-	value to assign
order	-	memory order constraints to enforce

Return value

The value of the atomic variable before the call.

See also

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)
exchange (C++14)	replaces the argument with a new value and returns its previous value (function template)