Atomically load a value and replace it with the sum of that value
and the supplied value i.
integral-type fetch_add( integral-type i, memory_order order = memory_order_seq_cst) volatile;
Atomically retrieves the existing value of *this and stores old-value
+ i
in *this.
The value of *this immediately prior to the
store.
Nothing.
This is an atomic read-modify-write operation for the memory
location comprising *this.
#include <atomic>