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Example Application: Calculation of Factorial, Permutation, and Combination

 

Permutation

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:

   

Practical Learning Practical Learning: Introducing Buttons

  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
     
    Factorial
    Permutation
    Combinatorial
  26. Close the form and return to your programming environment

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