std::istreambuf_iterator::equal
From cppreference.com
                    
                                        
                    < cpp | iterator | istreambuf iterator
                    
                                                            
                    | bool equal( const istreambuf_iterator& it ) const; | ||
Checks whether both *this and it are valid, or both are invalid, regardless of the stream buffer objects they use.
[edit] Parameters
| it | - | another stream buffer iterator to compare to | 
[edit] Return value
true if both *this and it are valid, or both are invalid, false otherwise.
[edit] Exceptions
(none)