CoSc2030: Computer Science II Fall Semester 2007 Instructor: Dr. Thomas Bailey

Lab 06: Lists

  The Linked List data type is one of several general ways to organize sequential data and is used frequently in many different branches of computer science. In this lab we will work with one implementation of the Linked List data type, specifically the one presented in class.  Remember that this structure stores one pointer to the front of the list.  Download the following files for today's lab node.h, LinkedListOne.cpp, LinkedListOne.h, OneDriver.cpp

Lab Assignment

1. The given list implementation stores its data as doubles.  Your task will be to write a double findSum() method inside of the LinkedList class that finds the sum of data stored in the list.  In order to perform this task you are going to need to use some form of iteration to traverse the list.  (Note: for this first problem you should use an iterative scheme and not recursion.)  For hints on how to write this function look at the method print in the LinkedList class. NOTE: be sure to test the find_sum method as well as all of the other methods that you write for this lab thoroughly.
    
2. For your second task we are going to have you create another method in the LinkedList class.  This method will be responsible for inserting the given parameter into the second position in the list.  The signature for this method will be void insertAsSecond(double x).  (Note:  Again use an iterative approach as opposed to recursion)  There are three special cases you should consider when writing this method.  
   
   1. An empty list - Should correctly insert the element in the front of the list.
   2. A one element list - Should correctly insert the element as the last element in the list.
   3. An n element list - Should correctly insert the element as the second element in the list.
3. For part three you will be creating a new LinkedList class called HTLinkedList.  The list is named HT for head and tail.  This list maintains two pointers, one to the head (front) of the list and one to the tail (back) of the list.  Create new files and use the provided LinkedList class as a starting point for building your new class.  In other words all of the methods should work properly for the HTLinkedList that worked for the LinkedList.  Use the Node class provided for the LinkedList implementation. 
4. Your final task is to implement an insertAsLast method for the HTLinkedList.  The signature for this method will be void insertAsLast(double x).  The method should properly handle the empty case as well as the other cases.  Consider the difficulty of inserting at the end of the LinkedList implementation versus the HTLinkedList implementation.  Which one is faster?  How much faster?  Why?  Place your answers to these questions inside the header file for the HTLinkedList.
   

   Notes:

   You are beginning your exploration of pointers and the strengths and weaknesses associated with them.  The code should be without runtime errors and memory leaks.  Use the write methods provided for you to test your code.  If you are unsure of your code be sure to ask you lab instructor for help.  To aid you in determining problems with your implementations we are going to have a overview of the Microsoft Visual C++ debugger.  Here is the code we are going to debug.

Turn In:

You should have 4 files to upload.  Write your name in comments at the top of each file.  Make sure your files are named Lab6LinkedList.cpp, Lab6LinkedList.h, Lab6HTLinkedList.cpp, and Lab6HTLinkedList.h .  As always labs are due 1 week past their assigned date.

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