在Vb.net中检查日期

Question

I have a problem where in excel one column contains a unique number in the form : mmdd followed by serial number 01,02.. For eg: 101201(10:month, 12:today's date, 01:first entry), 101202. Now, what I need is that my form in vb.net should take the last entered data (for eg: 101202) check if it is today's date. If yes, then it should add 1 and display it in a message box.(yes, then 101203 should be displayed). If not, then it should take current date and start with 01 (101301 in case, the date is 13/10/2016). I managed to get the data from previous row. But how should I check it with date? Please help!

   Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    xlWorkBook = xlApp.Workbooks.Open("C:\Users\Desktop\testing.xlsx")
    'xlApp.Visible = True
    xlWorkSheet = xlWorkBook.Sheets("Sheet1")

    Dim row As Long
    row = 1
    With xlWorkSheet
        While .Cells(row, 2).value IsNot Nothing
            row = row + 1
        End While
        'MsgBox(row - 1)
    End With

    Dim r As Excel.Range
    Dim t As String = Format(Today, "MMdd")
    If xlWorkSheet.Cells(row - 1, 4).value Is Nothing Then
        Me.txtQuote.Text = t & "01"
    Else
        r = xlWorkSheet.Cells(row - 1, 4)
        Me.txtQuote.Text = (r.Value + 1)
    End If

'this is wrong and I know it's wrong
    If r.Value = Date.Today Then
        MsgBox("true")
    Else
        MsgBox("false")
    End If

End Sub

Answer 1

Put this where you have written 'this is wrong and I know it's wrong

Dim rDate As String = CStr(r.Value).Substring(0, 4)
If rDate = t Then
    MsgBox("true")
Else
    MsgBox("false")
End If

rDate basically grabs the first 4 digits from r so now you can compare this to todays date. I have also replaced todays date with t because you have t already using today's date in the required format.

Also naming variables as t and r makes it hard to understand what they are used for.