ATOMIC_VAR_INIT

Expands to an expression that can be used to initialize an atomic variable of the same type as value.

The initial value of atomic object of automatic storage duration that is not explicitly initialized using this macro (until C17) is indeterminate. The default (zero) initialization of static and thread-local variables produces a valid value however.

When initializing an atomic variable, any concurrent access, even through an atomic operation, is a data race (it may happen if the address is immediately passed to another thread with a memory_order_relaxed operation).

Notes

This macro was a part of early draft design for C11 atomic types. It is not needed in C11, and is deprecated in C17 with plans to be removed in C2x.

References

See also