Input Iterators

• Specialized read_only forward iterator:

// comparison logic
bool  operator == (const Iterator& ) const;  // equality operator
bool  operator != (const Iterator& ) const;  // non-equality operator

// read-only element access (rvalue only)
const value_type& operator *  () const;      // dereference operator

// motion
Iterator&   operator ++ ();                  // prefix increment
Iterator    operator ++ (int);               // postfix increment

// proper type
            Iterator    ()                   // constructor
            ~Iterator   ()                   // destructor
            Iterator    (const Iterator& );  // copy constructor
//  no assignment operator