老师让做个VB程序 要求输入2个操作数和一个操作符,根据操作符号决定进行的运算 请问该怎么编写程序

添加一个Command,一个Text
Private Sub Command1_Click()
On Error GoTo err
Dim a, b, c, d
d = 0
a = InStr(Text1.Text, "+")
If a <> 0 Then GoTo toto1
d = 1
a = InStr(Text1.Text, "-")
If a <> 0 Then GoTo toto1
d = 2
a = InStr(Text1.Text, "*")
If a <> 0 Then GoTo toto1
d = 3
a = InStr(Text1.Text, "/")
If a = 0 Then
MsgBox "error"
Exit Sub
End If
toto1:
b = Left(Text1.Text, a - 1)
c = Right(Text1.Text, Len(Text1.Text) - a)
Select Case d
Case 0
MsgBox Val(b) + Val(c)
Case 1
MsgBox b - c
Case 2
MsgBox b * c
Case 3
MsgBox b / c
End Select
Exit Sub
err:
MsgBox "错误"
End
End Sub

Private Sub Command1_Click()
Dim