Introduction

In this exercise, we will develop an application for a small CD publishing company. The owner wants the prices to be calculated so a customer would get a discount if he orders more. To attract customers and encourage them to order more, she has decided to fix the prices so that the customer would pay:

• $20/CD if she orders less than 20 units
• $15/CD if she orders less than 50 units
• $12/CD if she orders less than 100 units
• $8/CD if she orders less than 500 units
• $5/CD if she orders more than 500 units

1. Start Microsoft Visual Basic and create a Standard EXE application
2. Save the application in a new folder named CD Publisher
3. Save the form as frmMain and save the project as CDPublisher
4. To use the needed spin button, on the main menu, click Project -> Components...
5. In the Components dialog box, click the Microsoft Windows Common Controls 6.0 (SP4) check box
    
   
6. Click OK
7. Design it as follows:
    

   Control Properties Form Name: frmMain Border Style: 3 - FixedDialog Caption: CD Publisher Label Caption: Number of CDs: TextBox Name: txtQuantity Alignment: 1 - Right Justify UpDown Name: updQuantity Alignment: 1 Buddy Control: txtQuantity Max: 10000 Label Caption: Unit Price: TextBox Name: txtUnitPrice Alignment: 1 - Right Justify Label Caption: Total Price: TextBox Name: txtTotalPrice Alignment: 1 - Right Justify CommandButton Name: cmdClose Caption: Close

8. Double-click the Close button and implement its Click event as follows:
    

   Private Sub cmdClose_Click() End End Sub

9. Double-click the UpDown control and implement its Change event as follows:
    

   Private Sub updQuantity_Change() Dim Quantity As Integer Dim UnitPrice, TotalPrice As Currency Quantity = CInt(txtQuantity.Text) If Quantity < 20 Then UnitPrice = 20 ElseIf Quantity < 50 Then UnitPrice = 15 ElseIf Quantity < 100 Then UnitPrice = 12 ElseIf Quantity < 500 Then UnitPrice = 8 Else UnitPrice = 5 End If TotalPrice = Quantity * UnitPrice txtUnitPrice.Text = CStr(UnitPrice) txtTotalPrice.Text = CStr(TotalPrice) End Sub

10. To allow the user to enter a quantity value, access the LostFocus event of the txtQuantity text box and implement it as follows:
     

    Private Sub txtQuantity_LostFocus() updQuantity_Change End Sub

11. Test the application