Visual Basic.NET How to Program (PDF)

230 Procedures Chapter 6
7 Friend WithEvents txtBase As TextBox ' reads base
8 Friend WithEvents txtPower As TextBox ' reads power
9
10 Friend WithEvents inputGroup As GroupBox
11
12 Friend WithEvents lblBase As Label ' prompts for base
13 Friend WithEvents lblPower As Label ' prompts for power
14 Friend WithEvents lblOutput As Label ' displays output
15
16 Friend WithEvents cmdCalculate As Button ' generates output
17
18 ' Visual Studio .NET generated code
19
20 ' reads input and displays result
21 Private Sub cmdCalculate_Click(ByVal sender As System.Object, _
22 ByVal e As System.EventArgs) Handles cmdCalculate.Click
23
24 Dim value As Integer
25
26 ' call version of Power depending on power input
27 If Not txtPower.Text = "" Then
28 value = Power(Convert.ToInt32(txtBase.Text), _
29 Convert.ToInt32(txtPower.Text))
30 Else
31 value = Power(Convert.ToInt32(txtBase.Text))
32 End If
33
34 lblOutput.Text = Convert.ToString(value)
35 End Sub ' cmdCalculate_Click
36
37 ' use iteration to calculate power
38 Function Power(ByVal base As Integer, _
39 Optional ByVal exponent As Integer = 2) As Integer
40
41 Dim total As Integer = 1
42 Dim i As Integer
43
44 For i = 1 To exponent
45 total *= base
46 Next
47
48 Return total
49 End Function ' Power
50
51 End Class ' FrmPower
Fig. Fig. 6.24 6.24 Optional argument demonstration with method Power (part 2 of 2).