std::unordered_set::clear
From cppreference.com
                    
                                        
                    < cpp | container | unordered set
                    
                                                            
                    |   void clear();  | 
(since C++11) | |
Removes all elements from the container. The past-the-end iterators are not invalidated.
Contents | 
[edit] Parameters
(none)
[edit] Return value
(none)
[edit] Exceptions
1-3)[edit] Complexity
linear in the size of the container.
[edit] See also
|    erases elements   (public member function)  | |