atomic_load, atomic_load_explicit
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header <stdatomic.h>
   | 
||
|   C atomic_load( volatile A* obj );  | 
(1) | (since C11) | 
|   C atomic_load_explicit( volatile A* obj, memory_order order );  | 
(2) | (since C11) | 
Atomically loads and returns the current value of the atomic variable pointed to by obj. The operation is atomic read operation. 
The first version orders memory accesses according to memory_order_seq_cst, the second version orders memory accesses according to order. order must be one of memory_order_relaxed, memory_order_consume, memory_order_acquire or memory_order_seq_cst. Otherwise the behavior is undefined.
This is a generic function defined for all atomic object types. A is the type of an atomic object, C is the non-atomic type corresponding to A.
[edit] Parameters
| obj | - | pointer to the atomic object to access | 
| order | - | the memory synchronization ordering for this operation | 
[edit] Return value
The current value of the atomic variable pointed to by obj.
[edit] See also
|    stores a value in an atomic object   (function)  | |
|   C++ documentation for atomic_load, atomic_load_explicit 
 | |