std::istream_iterator<T,CharT,Traits,Distance>::operator*, operator->
From cppreference.com
                    
                                        
                    < cpp | iterator | istream iterator
                    
                                                            
                    | const T& operator*() const; | (1) | |
| const T* operator->() const; | (2) | |
Returns a pointer or a reference to the current element.
The behavior is undefined if the iterator is end-of-stream iterator.
Parameters
(none)
Return value
A pointer or a reference to the current element.
Exceptions
May throw implementation-defined exceptions.