vb错误捕获前后时间相同怎么改

Question

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick Dim A As String Dim B As String Label1.Text = Int(Rnd() * 5) + 1 If Label1.Text = "1" Then A = Now.ToString("yy/MM/dd-HH;mm;ss") C = A & "温度故障请检修" If Label1.Text <> "" Then B = Now.ToString("yy/MM/dd-HH;mm;ss") ListBox1.Items.Add(C & B) End If End If End Sub我需要判断文本框是不是1，如果是1就将A和字符串赋值给C，1消失就让C连接B保存到列表框，A存的是1出现的时间，B存的是1消失的时间

Answer 1

添加一个变量err来标记错误是否已经发生，确保错误发生时间不会被反复更新。

    Private A As String
    Private B As String
    Private C As String
    Private err As Boolean = False
    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Label1.Text = Int(Rnd() * 5) + 1
        If Label1.Text = "1" And err = False Then
            A = Now.ToString("yy/MM/dd-HH;mm;ss")
            C = A & "温度故障请检修"
            err = True
        ElseIf Label1.Text <> "1" And err = True Then
            B = Now.ToString("yy/MM/dd-HH;mm;ss")
            ListBox1.Items.Add(C & B)
            err = False
        End If

    End Sub