微信摇骰子怎么控制:VB编写的计算器问题

谁能给我说下这个程序的编译原理
Option Explicit
Dim strNumber As String
Dim strPoint As String
Dim dblNum1 As Double
Dim intOperator As Integer
'清除结果
Private Sub cmdGT_Click()
txtDisplay.Text = "0."
strNumber = ""
strPoint = "."
intOperator = 7
End Sub
'输入数字
Private Sub cmdNumber_Click(Index As Integer)
strNumber = strNumber & cmdNumber(Index).Caption
txtDisplay.Text = strNumber & strPoint
End Sub

Private Sub cmdOnOff_Click()
End
End Sub
'运算过程
Private Sub cmdOperator_Click(Index As Integer)
Dim dblnum2 As Double
'是第一次单击运算符时，将输入的值先赋给第一个数，否则赋值给第二个数进行运算
If intOperator = 7 Then
dblNum1 = CDbl(txtDisplay.Text)
Else
dblnum2 = CDbl(Val(txtDisplay.Text))
'根据输入的符号进行运算
'求普通运算
Select Case intOperator
Case 0
dblNum1 = dblNum1 + dblnum2
Case 1
dblNum1 = dblNum1 - dblnum2
Case 2
dblNum1 = dblNum1 * dblnum2
Case 3
If dblnum2 <> 0 Then
dblNum1 = dblNum1 / dblnum2
Else
MsgBox "除数不能为“0”！请重新输入除数。", vbOKOnly + vbInformation, "除零错误"
Index = intOperator
End If
Case 6
dblNum1 = dblNum1 * dblnum2 / 100
End Select
End If

'取得当前输入的运算符，以做下次运算
intOperator = Index
strNumber = ""
txtDisplay = CStr(dblNum1)
'判断是否为文本框中的数字加点
If Not txtDisplay Like "*.*" Then
txtDisplay.Text = txtDisplay.Text & "."
End If
End Sub

Private Sub cmdOtherOper_Click(Index As Integer)
Dim dblNum As Double
'求平方根，平方，
dblNum = CDbl(Val(txtDisplay.Text))

Select Case Index
Case 0
'验证数据是否有效
If dblNum >= 0 Then
txtDisplay.Text = CStr(Sqr(dblNum))
Else
MsgBox "负数不能开平方根！", _
vbOKOnly + vbCritical, "开平方根错误"
End If
Case 1
txtDisplay.Text = CStr(dblNum ^ 2)
End Select
'判断是否为文本框中的数字加点
If Not txtDisplay Like "*.*" Then
txtDisplay.Text = txtDisplay.Text & "."
End If
End Sub
Private Sub cmdPoint_Click()
strNumber = strNumber & strPoint
strPoint = ""
End Sub

Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
'使被按下的数字键的对应按钮取得焦点
Select Case KeyCode
Case 48 To 57
cmdNumber(KeyCode - 48).SetFocus
Case 96 To 105
cmdNumber(KeyCode - 96).SetFocus
Case Else
'使按下的符号键对应的按钮取得焦点
If KeyCode = 107 Or (Shift = vbShiftMask And KeyCode = 187) Then
cmdOperator(0).SetFocus
cmdOperator_Click (0)
ElseIf KeyCode = 109 Or KeyCode = 189 Then
cmdOperator(1).SetFocus
cmdOperator_Click (1)
ElseIf KeyCode = 106 Or (Shift = vbShiftMask And KeyCode = 56) Then
cmdOperator(2).SetFocus
cmdOperator_Click (2)
ElseIf KeyCode = 111 Or KeyCode = 191 Then
cmdOperator(3).SetFocus
cmdOperator_Click (3)