list.cpp

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// Tutorial 16: List.cpp
// Class List member-function definitions.
#include <iostream> // required to perform C++-style stream I/O

using namespace std; // for accessing C++ Standard Library members

#include "List.h"  // List class definition

// List constructor
List::List()
{
   // initialize firstItem as a pointer to nothing
   setFirstItem( 0 );
 
} // end constructor

// set the pointer for the first item in the list
void List::setFirstItem( ShoppingItem *newFirstItem )
{
   firstItem = newFirstItem;
} // end function setFirstItem

// return a pointer to the first item in the list
ShoppingItem *List::getFirstItem()
{
   return firstItem;
} // end function getFirstItem

// add an item to the front of the list
void List::addItem( string itemName, int quantity )
{
   // create the new ShoppingItem
   ShoppingItem *newItem = new ShoppingItem( itemName, quantity, 0 );

   // update pointer to next item
   newItem->setNextItem( getFirstItem() ); 
   setFirstItem( newItem ); // add new item to the front of the list

} // end function addItem

// display each item in the list
void List::displayList()
{
   // get a pointer to the head of the list
   ShoppingItem *currentItem = getFirstItem();

   // display a header
   cout << "\nShopping List" << endl;
   cout << "-------------" << endl;

   // display information for each item
   while ( currentItem != 0 )
   {
      currentItem->display(); // display name and quantity
      currentItem = currentItem->getNextItem(); // move to next item
   } // end while

} // end function displayList

// delete each item in the list
void List::deleteList()
{
   // get a pointer to the head of the list
   ShoppingItem *currentItem = getFirstItem();
   
   // delete each item
   while ( currentItem != 0 )
   {
      // store a pointer to the next item
      ShoppingItem *nextItem = currentItem->getNextItem();
      cout << "\nMemory being released for: "
           << currentItem->getName() << endl;

      delete currentItem; // delete the current item

      // place a pointer to the next item in currentItem
      currentItem = nextItem;
   } // end while

} // end function deleteList


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