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Page 1057 NodePtr       head;            // External pointer to list NodePtr       newNodePtr;      // Pointer to newest node NodePtr       currPtr;         // Pointer to last node ComponentType inputVal; head = new NodeType; cin >> head->component; currPtr = head; cin >> inputVal; while (cin) {         // Invariant (prior to test):         //     All previous values of inputVal have been placed         //     into linked list pointed to by head         //  && currPtr points to last node in list     newNodePtr = new NodeType;         // Create new node     newNodePtr->component = inputVal;  // Set its component value     currPtr->link = newNodePtr;        // Link node into list     currPtr = newNodePtr;              // Set currPtr to last node     cin >> inputVal; } currPtr->link = NULL;                  // Mark end of list Let's do a code walk-through and see just how this algorithm works. head = new NodeType; A variable of type NodeType is created. The pointer is stored into head. Variable head will remain unchanged as the pointer to the first node (that is, head is the external pointer to the list). cin >> head->component; The first number is read into the component member of the first node in the list. currPtr = head; currPtr now points to the last node (the only node) in the list. cin >> inputVal; The next number (if there is one) is read into variable inputVal. while (cin) { An event-controlled loop is used to read input values until end-of-file occurs. newNodePtr = new NodeType; Another variable of type NodeType is created, with newNodePtr pointing to it.
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