Visual C++ Programming: Concepts and Projects Chapter 10B: Recursion (Tutorial)

Visual C++ Programming: Concepts and Projects

Chapter 10B: Recursion (Tutorial)

Tutorial: Generating a Fractal Image

• Problem Analysis– This project uses the recursive DrawBranch()

method– The result will be an interface upon which one

branch, with its recursive subbranches, is drawn– On Your Own tasks will allow more options– The program can easily be developed to have four

central branches

Programming with Visual C++ 2

Problem Analysis


Design

• Interface– Menus are created using the MenuStrip control– Menu items are named after the text they contain– If the text is numeric, the menu item names

default to numbered order– Menus control stopping the program and setting

the maximum levels of recursion


Design (continued)


Design (continued)


• Each menuItem requires a Click() event

Design (continued)


• Instance variables

Design (continued)


• Required Graphics and Drawing objects

Design (continued)


• Data table for DrawBranch()

Design (continued)


• Algorithms– For menu items that set maxLevels

Design (continued)


• Algorithm for DrawFractal()

Design (continued)


• Algorithm for method DrawBranch()

Design (continued)


Development

• Create the interface– Menus• The menuStrip control is used to add menuStrip

features to the program• The “Type here” labels indicate where menu headings

and items can be created


Development (continued)



• Menus– Menu headings are placed at the top level of each

menu– Menu items are listed below



• Declare instance variables and objects



• Initialization in Form1_Load()



• Coding the Exit menu



• Coding the level menu items



• Coding DrawFractal()



• Calling DrawBranch()


Testing

• Demonstrate that each level works correctly• Demonstrate that the Exit menu works


Testing (continued)


Analysis

• The number of recursive calls is factorial• The number of executions of DrawBranch() is O(3n)– n is maxLevels-1

• This program would demand considerable resources to complete a drawing involving a high number of levels


Analysis (continued)


On Your Own

• More central branches– Add three more central branches

• Add an angle menu– Varying the angle produces different fractal

images


On Your Own (continued)


Visual C++ Programming: Concepts and Projects Chapter 10B: Recursion (Tutorial)

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