ATOMIC_VAR_INIT

From cppreference.com
Defined in header <atomic>
#define ATOMIC_VAR_INIT(value) /* implementation-defined */

Expands the an expression which can be used to initialize an std::atomic object that can be initialized from value. If the atomic object has static storage duration, this initialization is constant initialization.

[edit] Notes

Accessing the variable during initialization from another thread, even through an atomic operation, is a data race (it may happen if the address is immediately passed to another thread with a std::memory_order_relaxed operation)

This macro is primarily provided for compatibility with C; it behaves the same as the constructor of std::atomic.

[edit] Example

[edit] See also

(C++11)
non-atomic initialization of a default-constructed atomic object
(function template)
constructs an atomic object
(public member function of std::atomic)