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

The Loop Program

	When you have finished this project, you will be able to:
	create a Do . . . Loop
	describe how a Do . . . Loop works and when it should be used
	create a For . . . Next loop
	describe how a For . . . Next loop works and when it should be used

1. Create a new folder called Loop on your personal drive.
   
   
2. Start Visual Basic and create a new project. Save the form and Project as Loop.
   
   
3. Add your programmer information and Option Explicit information to the beginning of the program.
   
   
4. The first looping structure that you will learn is the Do . . . Loop. A Do . . . Loop executes a set of statements as long as a condition is true.
   
   
5. You will create a prime number application to learn how to create a Do . . . Loop. You will recall that a prime number is a number that is divisible only by 1 and itself. 2, 3, and 7 are prime numbers, but 4, 6, and 9 are not because they are able to be divided by more than 1 and themselves.
   
   
6. Add the neceesary objects to your form using the Objects Table below.
   
   Objects Table

   Object	Property	Setting
   Form	Name	frmLoop
   	Caption	The Loop Program
   TextBox	Name	txtInteger
   	Text	No text
   Label	Name	lblEnterInteger
   	Caption	Enter an integer:
   Label	Name	lblPrimeResult
   Command Button	Name	btnTest
   	Caption	Check Test
   Command Button	Name	btnExit
   	Caption	Exit

   
   
   
7. Write the code for the Test button as illustrated below.
   
   
   
   
8. Save your program and run it. Try several numbers to find out if they are prime numbers or not.
   
   
9. The next type of loop that you will learn is a For . . . Next loop. Unlike the Do . . . Loop, a For . . . Next loop continues to run until a counter reaches an ending point. To learn how to create a For . . . Next loop, you will create a factorial progam. A factorial program is the product of all of the positive integers from 1 to the ending number. For example, 5 factorial is written as 5!, and means 5 * 4 * 3 * 2 * 1 for a product of 120.
   
   
10. Add the objects required for the Factorial Program to your Loop form. Use the Object Table below.
    
    Object Table
    

    Object	Property	Setting
    TextBox	Name	txtNumber
    	Text	No text
    Label	Name	lblEnterNumber
    	Caption	Enter a number:
    Label	Name	lblFactorialMessage
    Label	Name	lblFactorial
    Command Button	Name	btnComputeFactorial
    	Caption	Computer Factorial

    
    
    
11. The code for the Compute Factorial button is shown below.
    
    
    
    
12. Click here to see the marking guide for this project.
    
    
13. When you have finished, send an email to your teacher asking that this project be marked.