std::map<Key,T,Compare,Allocator>::value_comp
From cppreference.com
                    
                                        
                    
                    
                                                            
                    
|   std::map::value_compare value_comp() const;  | 
||
Returns a function object that compares objects of type std::map::value_type (key-value pairs) by using key_comp to compare the first components of the pairs.
Parameters
(none)
Return value
The value comparison function object.
Complexity
Constant.
See also
|    returns the function that compares keys  (public member function)  |