std::atomic_load, std::atomic_load_explicit
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header  <atomic>
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| (1) | (since C++11) | |
|   template< class T > T atomic_load( const std::atomic<T>* obj ) noexcept;  | 
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|   template< class T > T atomic_load( const volatile std::atomic<T>* obj ) noexcept;  | 
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| (2) | (since C++11) | |
|   template< class T > T atomic_load_explicit( const std::atomic<T>* obj,   | 
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|   template< class T > T atomic_load_explicit( const volatile std::atomic<T>* obj,   | 
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1) Atomically obtains the value pointed to by 
obj as if by obj->load()2) Atomically obtains the value pointed to by 
obj as if by obj->load(order)Parameters
| obj | - | pointer to the atomic object to modify | 
| order | - | the memory synchronization ordering for this operation: only std::memory_order_relaxed, std::memory_order_consume, std::memory_order_acquire and std::memory_order_seq_cst are permitted. | 
Return value
The value that is held by the atomic object pointed to by obj
See also
|    atomically obtains the value of the atomic object   (public member function of std::atomic<T>)  | |
|    (C++11)(C++11)  | 
   atomically replaces the value of the atomic object with a non-atomic argument   (function template)  | 
|    (C++11)  | 
   defines memory ordering constraints for the given atomic operation   (enum)  | 
|    specializes atomic operations for std::shared_ptr   (function template)  |