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std::atomic_ref<T>::exchange

T exchange( T desired, std::memory_order order = std::memory_order_seq_cst ) const noexcept;
 (since C++20)

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

Parameters

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

Return value

The value of the referenced object before the call.

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