Ross Sheppard High School
Computer Programming 20
Student Learning Guide
Controlling Program Flow with Decision Structures

The Decisions Program

	When you have finished this project, you will be able to:
	create a series of decision structures
	describe how each decision structure works
	explain the logic of decision structures

1. Create a new folder called Decisions on your personal drive.
   
   
2. Start Visual Basic and create a new project. Save the form and Project as Decisions.
   
   
3. Add your programmer information and Option Explicit information to the beginning of the program.
   
   
4. Your first task to to create a simple If . . . Then statement. Such a statement checks to see if a certain condition is true, then acts upon that condition.
   
   
5. Examine the code shown below:
   
   
6. The statement means that if the user guessed the same number as the secret number, then display a caption in the label.
   
   
7. Use the chart below to create the objects for this part of the program.
   
   Objects Table
   

   Object	Property	Setting
   Form	Name	frmDecisions
   	Caption	The Decisions Program
   TextBox	Name	txtGuess
   	Text	No text
   Label	Name	lblGuessMessage
   	Caption	Blank
   Label	Name	lblInstruction
   	AutoSize	True
   	Caption	Guess a number between 1 and 10
   Label	Name	lblMyGuess
   	Caption	My Guess
   Command Button	Name	btnCheckGuess
   	Caption	Check Guess
   Command Button	Name	btnExit
   	Caption	Exit

   
   
   
8. Your form should be similar to the one illustrated below.
   
   
   
   
9. Next, write the code for the Exit button.
   
   
10. Now, write the code for the Check Guess button.
    
    
    
    
11. Save your project and run it. You should be able to explain code such as this for a simple If . . . Then statement.
    
    
12. For the next part of this project, you will use Boolean logic to add to an If . . . Then statement. Boolean logic is similar in concept to what you have learned about mathematical operators in math class. The chart below describes the Boolean expressions that you can use.
    
    

    Operator	Meaning
    =	equals
    <	less than
    <=	less than or equal to
    >	greater than
    >=	greater than or equal to
    <>	not equal to

    
    
    
13. Boolean operators can be used within If . . . Then statements to evaluate certain conditions.
    
    
14. Use the objects table below to add to your Decisions program.
    
    Objects Table

    Object	Property	Setting
    TextBox	Name	txtGrade
    	Text	No text
    Label	Name	lblEnterGrade
    	AutoSize	True
    	Caption	Enter a mark
    Label	Name	lblResult
    	AutoSize	False
    	Caption	Blank
    CommandButton	Name	btnCheckGrade
    	Caption	Check Grade

15. Your form should be similar to the one illustrated below.
    
    
    
    
16. Next, write the code for the Check Grade button that makes use of a boolean operator. If the mark is greater than or equal to 70, then the label caption should read "Good job!". The code is
    
    
    
    
17. Save and run your program. Try entering a mark less than 70, then one greater than 70. The appropriate caption should be displayed in the label.
    
    
18. Next, change the code so that the caption will read "Study more!" if the mark is less than 70. This will make use of additional code to create an If . . . Then . . . Else statement. In other words, "if a certain condition is true, then do something, otherwise do something else."
    
    
    
    
19. Save and run your program. The appropriate caption should be displayed in each case.
    
    
20. Another type of decision structure that is useful is makes use of the ElseIf statement. ElseIf statements are used to solve a complex series of steps in a program - called an algorithm.
    
    
21. Use the Object table below to add the objects listed to your form.
    
    Object Table
    

    Object	Property	Setting
    TextBox	Name	txtGuess2
    	Text	No text
    Label	Name	lblGuessMessage2
    	Caption	Blank
    Label	Name	lblInstruction2
    	AutoSize	True
    	Caption	Guess a number between 1 and 10
    Label	Name	lblMyGuess2
    	Caption	My Guess 2
    Command Button	Name	btnCheckGuess2
    	Caption	Check Guess 2

    
    
    
22. Add the code to the Check Guess 2 button.
    
    
    
    
23. Make sure you understand what the above code does - you will need to know that when you write the pseudo-code for the Program Documentation form.
    
    
24. Save your project and run it. Try using various numbers to ensure all of the options work.
    
    
25. Add a command button to your form. The Name of the button is Print. You can complete the remainder of the properties yourself.
    
    
26. Add the following code to the Print button.
    
    
    
    
27. Save you program and run it. Test the Print button.
    
    
28. Next, remove the project by clicking on File in the Menu Bar, then on Remove Project. Start a new project and save it as Password in your Decisions folder.
    
    
29. Add the objects listed on the Object Table below to your form.
    
    Object Table
    

    Object	Property	Setting
    Form	Name	frmPassword
    	Caption	The Password Program
    TextBox	Name	txtPassword
    	Text	No text
    	PasswordChar	*
    Label	Name	lblMessage
    	Caption	Type a password to log on to the computer
    Label	Name	lblPassword
    	Caption	Password:
    Command Button	Name	btnOK
    	Caption	OK
    Command Button	Name	btnCancel
    	Caption	Cancel

30. Save the project. It should look similar to the illustration below.
    
    
    
    
31. Write the code for the Cancel button - use the same code as you usually use for an Exit button. Save your project
    
    
32. Shown below is the pseudo-code for the OK button.
    
    
    
    
33. The actual code is shown below.
    
    
    
    
34. It would be useful if the password form actually started the Decisions Program. Here is an overview of how to do this:
    • open the Decisions Program in design mode
    • add the Password form to the project - hint: right click on the frmDecisions in the project explorer, select add, then add the frmPassword (the frmPassword must be in the same folder as the frmDecisions)
    • on the Menu Bar, click on Project, then select the project properties
    • change the startup form to frmPassword
    • write code to when the user enters the proper password, the frmPassword unloads and the frm Decisions loads
      
      
35. Click here to see the marking guide for this project.
    
    
36. When you have finished, send an email to your teacher asking that this project be marked.