代码如下：
Dim t, t1 As Integer
Dim x, y As Double
Public Sub com()
x = Val(l1.Caption)
Select Case t1
Case Is = 1: y = y + x
Case Is = 2: y = y - x
Case Is = 3: y = y * x
Case Is = 4: y = y / x
End Select
t1 = 0
t = 0
l1.Caption = "0"
End Sub
Private Sub Form_Load()
x = 0
y = 0
t = 0
t1 = 1
End Sub
Private Sub c0_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "0"
Else
l1.Caption = l1.Caption + "0"
End If
End Sub
Private Sub C1_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "1"
Else
l1.Caption = l1.Caption + "1"
End If
End Sub
Private Sub c10_Click(Index As Integer)
If t = 0 Then
l1.Caption = l1.Caption + "."
t = 1
End If
End Sub
Private Sub C2_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "2"
Else
l1.Caption = l1.Caption + "2"
End If
End Sub
Private Sub C3_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "3"
Else
l1.Caption = l1.Caption + "3"
End If
End Sub
Private Sub C4_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "4"
Else
l1.Caption = l1.Caption + "4"
End If
End Sub
Private Sub C5_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "5"
Else
l1.Caption = l1.Caption + "5"
End If
End Sub
Private Sub C6_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "6"
Else
l1.Caption = l1.Caption + "6"
End If
End Sub
Private Sub C7_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "7"
Else
l1.Caption = l1.Caption + "7"
End If
End Sub
Private Sub C8_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "8"
Else
l1.Caption = l1.Caption + "8"
End If
End Sub
Private Sub C9_Click(Index As Integer)
If l1.Caption = "0" Then
l1.Caption = "9"
Else
l1.Caption = l1.Caption + "9"
End If
End Sub
Private Sub z1_Click(Index As Integer)
com
t1 = 1
End Sub
Private Sub z2_Click(Index As Integer)
com
t1 = 2
End Sub
Private Sub z3_Click(Index As Integer)
com
t1 = 3
End Sub
Private Sub z4_Click(Index As Integer)
com
t1 = 4
End Sub
Private Sub z5_Click(Index As Integer)
tmp = Mid(l1.Caption, Len(l1.Caption), 1)
If tmp = "." Then
t = 0
End If
If Len(l1.Caption) = 1 Then
l1.Caption = "0"
Else
l1.Caption = Left(l1.Caption, Len(l1.Caption) - 1)
End If
End Sub
Private Sub z6_Click(Index As Integer)
l1.Caption = "0"
Form_Load
End Sub
Private Sub z7_Click(Index As Integer)
If (l1.Caption <> "0") Then
l1.Caption = "-" + l1.Caption
End If
End Sub
Private Sub z8_Click(Index As Integer)
com
l1.Caption = Str(y)
End Sub
扩展资料
语言缺点
Visual Basic 语言具有不支持继承、无原生支持多线程、异常处理不完善等三项明显缺点，使其有所局限性（此些缺点皆已在 vb .net 获得改进）。
不支持继承
VB 5.0 和 VB 6.0 都是基于对象的编程语言，但是不包含继承特性。VB 中提供了特殊的类的功能，但是还是不能满足程序员的需求。
无原生支持多线程
Visual Basic 对于多线程无原生支持，只能通过Windows API的调用实现，且极其的不稳定。因为在API创建的线程中，并没有自动初始化运行时库，导致部分的函数无法使用。一般的，在VB6等早期的VB开发环境下，使用API创建线程的目的是完成容易使程序假死的大量数据或者逻辑的计算。
异常处理不完善
Visual Basic 中内置异常处理，即使未写异常处理代码，一旦用户出错也会弹出一个明确写出出错原因对话框，接着程序终止。
Visual Basic 中可以使用 Err.Raise抛出异常。对系统及用户抛出的异常的处理常用两种模式：一是使用 On Error Resume Next 处理错误；另一种是使用 On Error Goto 将运行引入错误处理代码。但相对 C++ 等语言而言，这样的异常处理破坏了代码的结构。
参考资料：百度百科-VB