Visual C++ Programming: Concepts and Projects Chapter 12B: Linked List (Tutorial)

Tutorial: Linked List Problem description – This program helps the user visualize a linked list by drawing one on the interface – Buttons are provided to: Create the initial list Add a Node to the front of the list Delete a Node from the front of the list Remove all Nodes (delete the list) 2Programming with Visual C++

Problem Description 3Programming with Visual C++

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Design The Node class definition – Start with a UML class diagram – All data members and methods will have public access (+) – Class variable: nodeCount – Instance variables: nodeData, next – Default constructor: Node() 12Programming with Visual C++

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Design (continued) Interface sketch – Equal distance between Node rectangles – Arrows drawn to link Nodes – Starting coordinates of the first Node are crucial The positions of all other Nodes are calculated from them 14Programming with Visual C++

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Design (continued) The head pointer The head pointer always points to the first Node in the list All insertions and deletions involve the head pointer 16Programming with Visual C++

Design (continued) Table of constants 17Programming with Visual C++

Design (continued) Table of Drawing objects 18Programming with Visual C++

Design (continued) Creating the first Node in a linked list 19Programming with Visual C++

Design (continued) Inserting a new Node – Create the new Node – Point the new Nodes next pointer at the first Node in the list – Assign the head pointer to point to the new Node This always inserts the new Node at the head of the linked list 20Programming with Visual C++

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Design (continued) Deleting a Node – Create a temporary Node pointer (temp) – Point temp at the first Node in the linked list – Assign the head pointer to point to the second Node – Delete the Node pointed to by temp This always deletes the Node at the head of the linked list 25Programming with Visual C++

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Design (continued) Use a loop to delete each node in the list Delete from the front Reassign head to point to the next Node Delete Nodes until there are no more 29Programming with Visual C++

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Development Interface – Only four buttons required Coding – Create Node.h (Node header file) – Create Node.cpp (implementation file) – Finish coding Form1.h (client code) 31Programming with Visual C++

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Development (continued) The Node class contains a default constructor – Change this to a prototype – Put the default constructor code in the implementation file (Node.cpp) 35Programming with Visual C++

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Development (continued) Enter the code for the Node class in Node.h 38Programming with Visual C++

Development (continued) Write the default constructor code in the implementation file ( Node.cpp ) Remember to include Node.h 39Programming with Visual C++

Development (continued) Client code ( Form1.h ) – Include the Node class definition file ( Node.h ) 40Programming with Visual C++

Development (continued) Client code ( Form1.h ) – Constants, head pointer, and Drawing objects 41Programming with Visual C++

Development (continued) Client code ( Form1.h ) – Code Form1->Load() Instantiate Drawing objects 42Programming with Visual C++

Development (continued) Client code ( Form1.h ) – Code the reset() method Properly enable all buttons Reset class variable Node::nodeCount to 0 43Programming with Visual C++

Coding Write code for btnHead_Click() – Create new head pointer – Draw the linked list – Properly reset the buttons 44Programming with Visual C++

Coding (continued) Write the code for btnInsert_Click() – No more than seven Nodes allowed – Implement three-step insertion algorithm – Draw the linked list 45Programming with Visual C++

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Coding (continued) Code drawNode() – drawNode() is recursive – level is used to determine when to stop drawing Nodes – The location of each Node rectangle is calculated by multiplying nodeDistance and level 47Programming with Visual C++

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Coding (continued) Draw the current Node If there is another Node linked to it ( next is not the nullptr ), then draw that Node – This is a recursive process – The base case occurs when next is the nullptr 50Programming with Visual C++

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Testing Check each button – Create a list – Insert nodes (make sure the nodeData is correct) – Try to insert more than seven (not allowed) 53Programming with Visual C++

On Your Own Task 1. Coding btnDelete_Click() Task 2. Coding btnClear_Click() and deleteList() Task 3. Final Testing to make sure all buttons work correctly Programming with Visual C++54

On Your Own (continued) 55Programming with Visual C++