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Example Application:
Elementary Operations
 
Elementary Operations

This application can assist a student from elementary or primary school perform some arithmetic operations. The application allows a user to select a level:

  • Level 1: In this level, the student deals with single-digit numbers (from 1 to 9)
  • Level 2: The second level uses numbers that range from 10 to 29
  • Level 3: This level generates numbers from 30 to 50
  • Level 4: The last level submits numbers that include 50, 100, and those in between

After selecting a level, the user can choose the type of operation to perform. The available operations are the addition, the subtraction, the multiplication, and the division.

To do an exercise, the user can click the New Operation button. The application then randomly generates two numbers and waits for the user to enter an answer. After typing a result, the user can click the Check Result button. A message would then come up to indicate whether the user's answer was right or wrong.
 
 

Practical LearningPractical Learning: Creating the Application
  1. Create a new Window Application named ElementaryOperations1
  2. In the Solution Explorer, right-click Form1.vb and click Rename
  3. Set the name to Exercise.vb
  4. Design the form as follows:
     
    Elementary Addition
    Control Text Name TextAlign Font Additional Properties
    Label Select Your Level        
    GroupBox          
    RadioButton Level 1 rdoLevel1 MiddleCenter Microsoft Sans Serif, 12pt, style=Bold Appearance: Button
    Checked: TRue
    RadioButton Level 2 rdoLevel2 MiddleCenter Microsoft Sans Serif, 12pt, style=Bold Appearance: Button
    RadioButton Level 3 rdoLevel3 MiddleCenter Microsoft Sans Serif, 12pt, style=Bold Appearance: Button
    RadioButton Level 4 rdoLevel4 MiddleCenter Microsoft Sans Serif, 12pt, style=Bold Appearance: Button
    Label Select the OPeration        
    GroupBox          
    RadioButton Addition rdoAddition MiddleCenter Microsoft Sans Serif, 12pt, style=Bold Appearance: Button
    Checked: TRue
    RadioButton Subtraction rdoSubtraction MiddleCenter Microsoft Sans Serif, 12pt, style=Bold Appearance: Button
    RadioButton Multiplication rdoMultiplication MiddleCenter Microsoft Sans Serif, 12pt, style=Bold Appearance: Button
    RadioButton Division rdoDivision MiddleCenter Microsoft Sans Serif, 12pt, style=Bold Appearance: Button
    Label 000 lblOperand1 MiddleRight Microsoft Sans Serif, 54pt  
    Button New Operation btnNewOperation   Microsoft Sans Serif, 20pt  
    Label + lblOperation MiddleRight Microsoft Sans Serif, 54pt  
    Label 00 lblOperand2 MiddleRight Microsoft Sans Serif, 54pt  
    Panel         Size: 317, 10
    Label =   Center Microsoft Sans Serif, 54pt AutoSize: True
    ForeColor: Green
    TextBox 000 txtResult Right Microsoft Sans Serif, 54pt, style=Bold  
    Button Check Result btnCheckResult      
  5. Double-click the New Operation button and implement its event as follows:
      
    Private Sub btnNewOPerationClick(ByVal sender As System.Object, 
				  ByVal e As System.EventArgs) 
				  Handles btnNewOPeration.Click
    Dim Number1 As Integer
    Dim Number2 As Integer
    Dim rndNumber As Random

    rndNumber = New Random

    ' If the user clicked the Level 1 button,
    ' the operation will be performed on numbers from 1 to 9
    If rdoLevel1.Checked = True Then
    	Number1 = rndNumber.Next(1, 10)
    	Number2 = rndNumber.Next(1, 10)
    ElseIf rdoLevel2.Checked = True Then
	' If the user clicked the Level 2 button,
	' the operation will be performed on numbers from 10 to 19
	Number1 = rndNumber.Next(10, 30)
	Number2 = rndNumber.Next(10, 30)
    ElseIf rdoLevel3.Checked = True Then
	' If the user clicked the Level 3 button,
	' the operation will be performed on numbers from 21 to 49
	Number1 = rndNumber.Next(30, 50)
	Number2 = rndNumber.Next(30, 50)
    ElseIf rdoLevel4.Checked = True Then
	' If the user clicked the Level 4 button,
	' the operation will be performed on numbers from 51 to 99
	Number1 = rndNumber.Next(50, 101)
	Number2 = rndNumber.Next(50, 101)
    End If

    ' Display the numbers to the user
    lblOperand1.Text = CStr(Number1)
    lblOperand2.Text = CStr(Number2)

    ' Just in case, empty the Result text box
    txtResult.Text = ""
    ' Give focus to the Result text box
    txtResult.Focus()
End Sub
  6. In the Class Name combo box, select rdoLevel1
  7. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub rdoLevel1Click(ByVal sender As Object, 
                                ByVal e As System.EventArgs) 
                                Handles rdoLevel1.Click
        ' When the user clicks the Level 1 button,
        ' behave as if the user had click the New Operation button
        ' That is, behave as if the user wants a new operation
        btnNewOPerationClick(sender, e)
End Sub
  8. In the Class Name combo box, select rdoLevel2
  9. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub rdoLevel2Click(ByVal sender As Object, 
                                ByVal e As System.EventArgs) 
                                Handles rdoLevel1.Click
        btnNewOPerationClick(sender, e)
End Sub
  10. In the Class Name combo box, select rdoLevel3
  11. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub rdoLevel3Click(ByVal sender As Object, 
                                ByVal e As System.EventArgs) 
                                Handles rdoLevel1.Click
        btnNewOPerationClick(sender, e)
End Sub
  12. In the Class Name combo box, select rdoLevel4
  13. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub rdoLevel4Click(ByVal sender As Object, 
                                ByVal e As System.EventArgs) 
                                Handles rdoLevel1.Click
        btnNewOPerationClick(sender, e)
End Sub
  14. In the Class Name combo box, select rdoAddition
  15. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub rdoAdditionClick(ByVal sender As Object, 
                                  ByVal e As System.EventArgs) 
                                  Handles rdoAddition.Click
        lblOperation.Text = "+"
End Sub
  16. In the Class Name combo box, select rdoSubtraction
  17. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub rdoSubtractionClick(ByVal sender As Object, 
                                     ByVal e As System.EventArgs) 
                                     Handles rdoSubtraction.Click
        lblOperation.Text = "-"
End Sub
  18. In the Class Name combo box, select rdoMultiplication
  19. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub rdoMultiplicationClick(ByVal sender As Object, 
                                        ByVal e As System.EventArgs) 
                                        Handles rdoMultiplication.Click
        lblOperation.Text = "*"
End Sub
  20. In the Class Name combo box, select rdoDivision
  21. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub rdoDivisionClick(ByVal sender As Object, 
                                  ByVal e As System.EventArgs) 
                                  Handles rdoDivision.Click
        lblOperation.Text = "/"
End Sub
  22. In the Class Name combo box, select btnCheckResult
  23. In the Method Name combo box, select Click and implement its event as follows:
      
    Private Sub btnCheckResultClick(ByVal sender As Object, 
                                     ByVal e As System.EventArgs) 
                                     Handles btnCheckResult.Click
        Dim Number1 As Double
        Dim Number2 As Double
        Dim UserResult As Double
        Dim OurResult As Double
        Dim RandomNumber As Random = New Random

        ' It is hard to perform a comparison on a division
        ' So we will have to do some gymastic here to get something
        ' We will use this variable to format the number 
        ' to appear as 0.00
        ' That will allow us to perform the comparision
        ' on a decimal number with a precision of 2
        Dim strFixedResult As String
        strFixedResult = ""

        Dim Congratulations As String() = { 
            "Right :) - WOW - Good Answer!", 
            "Good Answer :) - You are Impressive", 
            "Right Answer :) - What a Good Job!", 
            "Good :) - You Are Greaaaaaaaaaaaat", 
            "Wonderful Answer :) - You Know It" 
            }
        Dim WrongAnswers As String() = { 
            "Uhhhhhhhhhh - Bad Answer", 
            "Wrong - You will do better next time", 
            "Nop", 
            "Common - You can do Better Than That!", 
            "No - You are probably getting tired" 
            }

        ' Make sure the user provides a result
        If txtResult.Text = "" Then
            MsgBox("You must provide a result before clicking the button")
            Exit Sub
        End If

        ' Use exception handling to get the result
        Try
            UserResult = CDbl(txtResult.Text)

            Number1 = CDbl(lblOperand1.Text)
            Number2 = CDbl(lblOperand2.Text)

            ' Get the user's answer
            If rdoAddition.Checked = True Then
                OurResult = Number1 + Number2
                ' Format the result to appear with 2 decimal numbers
                strFixedResult = String.Format("{0:F}", Number1 + Number2)
            End If

            If rdoSubtraction.Checked = True Then
                OurResult = Number1 - Number2
                strFixedResult = String.Format("{0:F}", Number1 - Number2)
            End If

            If rdoMultiplication.Checked = True Then
                OurResult = Number1 * Number2
                strFixedResult = String.Format("{0:F}", Number1 * Number2)
            End If

            If rdoDivision.Checked = True Then
                OurResult = Number1 / Number2
                strFixedResult = String.Format("{0:F}", Number1 / Number2)
            End If

            ' Check if the user's answer is the right one
            ' Because of the division, we will format the result as 0.00
            ' then perform the comparison
            If strFixedResult = CDbl(txtResult.Text).ToString("F") Then
                MsgBox(Congratulations(RandomNumber.Next(0, 4)), 
                        MsgBoxStyle.OkOnly Or MsgBoxStyle.Question, 
                        "Elementary Operations")
            Else
                MsgBox(WrongAnswers(RandomNumber.Next(0, 4)), 
                        MsgBoxStyle.OkOnly Or MsgBoxStyle.Information, 
                        "Elementary Operations")
            End If

            ' After checking the user's answer, generate a new operation
            btnNewOPerationClick(sender, e)
        Catch ex As Exception
            MsgBox("Invalid Numeric Value.")
        End Try
End Sub
  24. Execute the application and test it
     
  25. Close the form and return to your programming environment

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