如何在vb中减去两个日期。如果条件

Question

您好，如果他们使用if then陈述满足条件，那么在减去日期方面会遇到一些问题，请您帮我找到它。所有用户的拳头将输入一个日期，然后添加350天，因此我们有两个日期。然后将其减去并多重播放，然后添加一些已标识的值。

  Private Sub CalculateButton_Click(sender As Object, e As EventArgs) Handles CalculateButton.Click
        Dim intdep_number As Integer​
        Dim dtmexpierdate As Date​
        Dim A As Integer​
        Dim B As Integer​
        Dim C As Integer​
        Dim days As Integer​
        Dim dtmIssuedate As Date​
        Dim intThirdA As Integer = 7310​
        Dim intFirstA As Integer = (3650 / 3)​
        Dim intSecondA As Integer = 3650​
        intdep_number = NumberofDependentTextBox.Text​
        dtmexpierdate = DateTimePicker2.Value​
        days = Val(365)​
        Label1.Text = ("The date sum is:" & " " & DateAdd(DateInterval.Day, days, dtmexpierdate))​
​
        If (dtmexpierdate <= Date.FromOADate(30 / 6 / 2019)) Then​
            A = DateDiff(DateInterval.Day, dtmexpierdate.Date, Date.FromOADate(30 / 6 / 2018).Date) + intFirstA * (20 / 3)​
​
        ElseIf (dtmexpierdate.ToString <= Date.FromOADate(30 / 6 / 2020)) Then​
            A = DateDiff(DateInterval.Day, dtmexpierdate.Date, Date.FromOADate(30 / 6 / 2019).ToString) + intSecondA * (10)​
​
        Else​
            A = DateDiff(DateInterval.Day, dtmexpierdate.Date, Date.FromOADate(30 / 6 / 2020).ToString) + intThirdA * (13.3)​
        End If​
​
        If (dtmIssuedate <= Date.FromOADate(30 / 6 / 2019)) Then​
            B = DateDiff(DateInterval.Day, dtmIssuedate.Date, Date.FromOADate(30 / 6 / 2018).ToString) + intFirstA * (20 / 3)​
​
        ElseIf (dtmIssuedate.ToString <= Date.FromOADate(30 / 6 / 2020)) Then​
            B = DateDiff(DateInterval.Day, dtmIssuedate.Date, Date.FromOADate(30 / 6 / 2019).ToString) + intSecondA * (10)​
​
        Else​
            B = DateDiff(DateInterval.Day, dtmIssuedate.Date, Date.FromOADate(30 / 6 / 2020).ToString) + intThirdA * (13.3)​
        End If​
        C = (B - A) - 1​
        Label2.Text = C * intdep_number​
    End Sub