Description

This application demonstrates the use of the button control of Microsoft Windows. It does this while calculating the factorial, the permutation, and the combinatorial.

Windows Controls:

• Label
• Button
• Text Box
• Tab Control

1. Start Microsoft Visual Basic and create a Windows Application named Algebra1
2. In the Solution Explorer, right-click Form1.vb and click Rename
3. Type Exercise.vb and press Enter
4. Click the body of the form to make sure it is selected.
   In the Properties window, change the following characteristics
   FormBorderStyle: FixedDialog
   Text: Factorial, Permutation, and Combination
   Size: 304, 235
   StartPosition: CenterScreen
   MaximizeBox: False
   MinimizeBox: False
5. In the Containers section of the Toolbox, click TabControl and click the form
6. On the form, right-click the right side of tabPage2 and click Add Page
7. Design the form as follows:
    

   Control Text Name Additional Properties TabControl   tclAlgebra HotTrack: True Location: 12, 12 Size: 304, 235 TabPage Factorial tabFactorial   Label Number:   Location: 22, 21 TextBox   txtNumber TextAlign: Right Location: 88, 18 Size: 50, 20 Label Result:   Location: 22, 56 TextBox   txtFactorial TextAlign: Right Location: 88, 54 Size: 140, 20

   Control Text Name Location Size TabPage Permutation tabPermutation     Label n:   22, 21   TextBox   txtPermutationN 88, 18 50, 20 Label r:   22, 56   TextBox   txtPermutationR 88, 54 50, 20 Label P(n, r):   22, 92   TextBox   txtPermutation 88, 90 140, 20

   Control Text Name Location Size TabPage Combination tabCombination     Label n:   22, 21   TextBox   txtCombinationN 88, 18 50, 20 Label r:   22, 56   TextBox   txtCombinationR 88, 54 50, 20 Label C(n, r):   22, 92   TextBox   txtCombination 88, 90 140, 20

8. Right-click the form and click View Code
9. Create the following functions:
   

   Public Class Exercise
       Private Function Factorial(ByVal x As Long) As Long
           If x <= 1 Then
               Return 1
           Else
               Factorial = x * Factorial(x - 1)
           End If
       End Function
   
       Private Function Permutation(ByVal n As Long, ByVal r As Long) As Long
           If r = 0 Then Permutation = 0
           If n = 0 Then Permutation = 0
           If (r >= 0) And (r <= n) Then
               Permutation = Factorial(n) / Factorial(n - r)
           Else
               Permutation = 0
           End If
       End Function
   
       Private Function Combinatorial(ByVal a As Long, ByVal b As Long) As Long
           If a <= 1 Then Combinatorial = 1
   
           Combinatorial = Factorial(a) / (Factorial(b) * Factorial(a - b))
       End Function
   End Class

10. Click the Exercise.vb [Design] tab
11. In the combo box on top of the Properties window, select tabFactorial
12. From the Common Controls section of the Toolbox, click Button and click on the right side of the top text box
13. Access each tab page and add a button to it
14. Add a button to the form under the tab control
15. Complete the design of the form as follows:
     

    Control Text Name Button Calculate btnCalcFactorial Button Close btnClose

    Control Text Name Button Calculate btnCalcPermutation

    Control Text Name Button Calculate btnCalcCombination

16. Right-click the form and click View Code
17. In the Class Name combo box, select btnCalc Factorial
18. In the Method Name combo box, select Click and implement the event as follows:
    

    Private Sub btnCalcFactorial_Click(ByVal sender As Object,
                                           ByVal e As System.EventArgs)
                                           Handles btnCalcFactorial.Click
            Dim number As Long
            Dim Result As Long
    
            Try
                number = CLng(txtFactNumber.Text)
                Result = Factorial(number)
                txtFactorial.Text = Result.ToString()
            Catch ex As Exception
                MsgBox("Invalid Number")
            End Try
    End Sub

19. In the Class Name combo box, select btnCalc Permutation
20. In the Method Name combo box, select Click and implement the event as follows:
    

    Private Sub btnCalcPermutation_Click(ByVal sender As Object,
                                             ByVal e As System.EventArgs)
                                             Handles btnCalcPermutation.Click
            Dim n As Long
            Dim r As Long
            Dim Result As Long
    
            Try
                n = CLng(txtPermutationN.Text)
            Catch ex As Exception
                MsgBox("Invalid Number")
            End Try
    
            Try
                r = CLng(txtPermutationR.Text)
                Result = Permutation(n, r)
                txtPermutation.Text = Result.ToString()
            Catch ex As Exception
                MsgBox("Invalid Number")
            End Try
    End Sub

21. In the Class Name combo box, select btnCalc Combination
22. In the Method Name combo box, select Click and implement the event as follows:
    

    Private Sub btnCalcCombination_Click(ByVal sender As Object,
                                             ByVal e As System.EventArgs)
                                             Handles btnCalcCombination.Click
            Dim n As Long
            Dim r As Long
            Dim Result As Long
    
            Try
                n = CLng(txtCombinationN.Text)
            Catch ex As Exception
                MsgBox("Invalid Number")
            End Try
    
            Try
                r = CLng(txtCombinationR.Text)
                Result = Combinatorial(n, r)
                txtCombination.Text = Result.ToString()
            Catch ex As Exception
                MsgBox("Invalid Number")
            End Try
    End Sub

23. In the Class Name combo box, select btn Close
24. In the Method Name combo box, select Click and implement the event as follows:
    

    Private Sub btnClose_Click(ByVal sender As Object,
                                   ByVal e As System.EventArgs)
                                   Handles btnClose.Click
            End
    End Sub

25. Execute the application to test the calculations
     
26. Close the form and return to your programming environment

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