在vb.net的日期值中添加月份

Question

I am trying the following code and getting the sql date time overflow exception.....The problem lies in the Gold part...rest to ie Silver and Premium work fine....When in Gold part I try to add certain number of months to a date time field I don't know what action is performed as when i check it through Message box the ren_date has value "12:00:00 AM" rather than the new date value after adding 6 months in mem_date value....

        Dim ren_date, mem_date As Date
        Dim renmon As String

        mem_date = TxtMemDate.Text

        ' checks the type of membership and adds corresponding number of years to the membership date and stores in renewal date

        If ComboBox1.SelectedItem = "Silver" Then
            ren_date = mem_date.AddMonths(3)
            renmon = ren_date.ToString("MMMM")
        ElseIf ComboBox1.SelectedItem = "Premium" Then
            ren_date = mem_date.AddYears(1)
            renmon = ren_date.ToString("MMMM")
        ElseIf ComboBox1.SelectedItem = "Gold" Then
            ren_date = mem_date.AddMonths(6)
            renmon = ren_date.ToString("MMMM")
        End If

        MsgBox(mem_date)
        MsgBox(ren_date)

Answer 1

I suspect your issue is actually here:

mem_date = TxtMemDate.Text

It may be that the String you're trying to coerce to a Date here isn't in the right format. Try putting a breakpoint after this line and go through with a debugger to experiment.

---

Here's another thing to try: maybe your ComboBox1.SelectedItem does not exactly match the string "Gold." Add an Else block to your If and put in there something like

MsgBox("*" & ComboBox1.SelectedItem.ToString() & "*")

This should reveal if there are, for example, leading or trailing spaces around the item's text.

Answer 2

This code performs as expected

Dim ren_date, mem_date As DateTime
Dim renmon As String = ""

If DateTime.TryParse(TxtMemDate.Text, mem_date) Then 'convert text to date
    ' checks the type of membership and adds corresponding number of years to the membership date and stores in renewal date
    If ComboBox1.SelectedItem.ToString = "Silver" Then
        ren_date = mem_date.AddMonths(3)
        renmon = ren_date.ToString
    ElseIf ComboBox1.SelectedItem.ToString = "Premium" Then
        ren_date = mem_date.AddYears(1)
        renmon = ren_date.ToString
    ElseIf ComboBox1.SelectedItem.ToString = "Gold" Then
        ren_date = mem_date.AddMonths(6)
        renmon = ren_date.ToString
    End If
    Debug.WriteLine(renmon)
Else
    Debug.WriteLine("Date entered is not correct format")
End If