用Visual Basic制作一个简易计算器``作好后追加50分!`

Dim a As Single, c As Integer

Private Sub Command1_Click(Index As Integer)
Text1.Text = Text1.Text + Command1(Index).Caption
End Sub

Private Sub Command2_Click()
b = Val(Text1.Text)
Select Case c
Case 0
a = a + b
Case 1
a = a - b
End Select
Text1.Text = a

End Sub

Private Sub Command3_Click(Index As Integer)
If a = 0 Then
a = Text1.Text
Else
b = Text1.Text
End If
Text1.Text = ""
Select Case Index
Case 0
a = a + b
Case 1
a = a - b
End Select
c = Index
End Sub

Private Sub Command4_Click()
a = 0: b = 0
Text1.Text = ""
End Sub

我有现成的