上机操作的代码和示意图(计算器)

计算器

Public Class Form1

Dim operand1, operand2 As Decimal

Dim oper As String

Dim x As Decimal

Private Sub digit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click, Button8.Click, Button7.Click, Button4.Click, Button6.Click, Button5.Click, Button11.Click, Button16.Click, Button15.Click

Label1.Text = CDec(Label1.Text & CType(sender, Button).Text).ToString

End Sub

Private Sub zero_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click

If Label1.Text <> "0" And Label1.Text <> "-0" Then

Label1.Text = Label1.Text & "0"

End If

End Sub

Private Sub period_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click

If Label1.Text.IndexOf(".") = -1 Then

Label1.Text = Label1.Text & "."

End If

End Sub

Private Sub negative_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click

If Label1.Text.Chars(0) <> "." Then

Label1.Text = "." & Label1.Text

Else

Label1.Text = Label1.Text.Remove(0, 1)

End If

End Sub

Private Sub operator_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button20.Click, Button18.Click, Button17.Click, Button19.Click

operand1 = CDec(Label1.Text)

oper = CType(sender, Button).Text

Label1.Text = "0"

End Sub

Private Sub equals_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click

Dim Result As Decimal

operand2 = CDec(Label1.Text)

Select Case oper

Case "+"

Result = operand1 + operand2

Case "-"

Result = operand1 - operand2