下面这段代码，是我用来计算每个月存500元进银行，连续30年，最后连本带利能有多少钱。这里面涉及复利计算。界面中右边的文本框用来输出每一次计算的结果。
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Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim nianxian As Integer '年限变量
Dim dingcun As Integer '定存变量
Dim fuli_big As Long '大复利
Dim fuli_small As Long '小复利
Dim i As Integer '循环变量
Dim DATAstring As String '数据字符串
nianxian = Val(年限_TextBox.Text)
dingcun = Val(定存_TextBox.Text)
DATAstring = ""
For i = 1 To nianxian
fuli_small = dingcun * (1 + 0.1875)
dingcun = fuli_small
fuli_big = fuli_big + fuli_small
DATAstring = DATAstring + "[" + Trim(Str(i)) + "]" + Str(fuli_big) + Chr(13) + Chr(10)
'DATAstring = DATAstring + "[" + Trim(Str(i)) + "]" + Str(fuli_small) + Chr(13) + Chr(10)
Next
'fuli_big = fuli_small
TextBox1.Text = DATAstring
结果_TextBox.Text = Str(fuli_big) + "元"
End Sub
'vb.net的串口接收数据要用到委托
Delegate Sub SetTextCallback(ByVal InputString As String) '声明一个委派类，并声明符合函数参数有一个，而其型态是字符串
Private Sub ShowString(ByVal comData As String)
txt_Re.Text = comData '将收到的数据入接收文字框中--- txt_Re.Text 是接收用的文本框
txt_Re.SelectionStart = txt_Re.Text.Length
txt_Re.ScrollToCaret()
End Sub
Private Sub SerialPort1_DataReceived(ByVal sender As Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived‘自动接收事件
Dim inData As String = SerialPort1.ReadExisting
Dim d As New SetTextCallback(AddressOf ShowString)
Invoke(d, inData)
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click '发送指令
SerialPort1.Write("123")
End Sub
j = 0
For i = 1 To 16 Step 1
If comISP.PortOpen = True Then '先关闭串口
comISP.PortOpen = False
End If
comISP.CommPort = i
On Error Resume Next '说明当一个运行时错误发生时，控件转到紧接着发生错误的语句之后的语句，并在此继续运行。访问对象时要使用这种形式而不使用 On Error GoTo。
comISP.PortOpen = True
If Err.Number 8002 Then '无效的串口号。这样可以检测到虚拟串口，如果用Err.Number = 0的话检测不到虚拟串口
If j = 0 Then
j = i
End If
cboPort.AddItem "COM" i '生成串口选择列表
End If
comISP.PortOpen = False
Next i
If j = 1 Then
cboPort.Text = "COM" j '自动打开可用的最小串口号
comISP.CommPort = j
comISP.PortOpen = True
cmdOpenCom.Caption = "关闭串口"
shpCOM.FillColor = vbGreen
If Err.Number = 8005 Then '串口已打开,vbExclamation '
comISP.PortOpen = False
cboPort.Text = ""
cmdOpenCom.Caption = "打开串口"
shpCOM.FillColor = vbRed
End If
End If
