/*
 * Program to demonstrate pointer based linked lists.
 */

/*
 * @class List
 * ADT list - Pointer-based implementation.
 */
class List
{
public:
  // Constructors and destructor:
  List(); // Default constructor
  List(const List& aList); // Copy constructor. Pass list to copy.
  ~List(); // Destructor

  // List operations:
  bool isEmpty() const; // 'const' signifies that this function can not
			// modify any class data members (unless member is
			// declared 'mutable'.
  int getLength() const;
  void insert(int index,
	      const int& newItem); // 'newItem' cannot be updated. 'int&' -->
				   // reference var, cannot refer to another
				   // object.
  void remove(int index);
  void retrieve(int index, int& dataItem) const;

private:
   /** A node on the list. */
   struct ListNode
   {
     int item;
     ListNode *next; // Pointer to next node.
   };

  int       size; // Number of items in list
  ListNode *head; // Pointer to linked list of items

  /** Locates a specified node in a linked list.
   * @pre index is the number of the desired node.
   * @post None.
   * @param index The index of the node to locate.
   * @return A pointer to the index-th node. If index < 1
   *         or index > the number of nodes in the list,
   *         returns NULL. */
  ListNode *find(int index) const;
};