Date validation!

Dim StartDate as Date
Dim EndDate as Date
  If Not IsDate(Text1.Text) Then
    'Text1 isnt a date
  ElseIf Not IsDate(Text2.Text) Then
    'Text2 isnt a date
  Else
    StartDate = Text1.Text
    EndDate = Text2.Text

    If Month(DateAdd("d",-1,StartDate)) = Month(StartDate) Then
      'Start date is not valid
    End If

    If Month(DateAdd("d",1,EndDate)) = Month(EndDate) Then
      'End date is not valid
    End If
  End If

Another approach...

Option Explicit

Private Sub Command1_Click()
    Dim dtStart As Date
    Dim dtStartFirst As Date
    Dim dtEnd As Date
    Dim dtEndLast As Date
       
    If IsDate(Text1.Text) Then
        dtStart = CDate(Text1.Text)
        dtStartFirst = getFirst(dtStart)
        Label1.Caption = dtStartFirst ' just to show the return value of getFirst()
        If dtStart <> dtStartFirst Then
            MsgBox "Start Date Must be the First of the Month"
        End If
    Else
        MsgBox "Invald Start Date"
    End If
   
    If IsDate(Text2.Text) Then
        dtEnd = CDate(Text2.Text)
        dtEndLast = getLast(dtEnd)
        Label2.Caption = dtEndLast ' just to show the return value of getLast()
        If dtEnd <> dtEndLast Then
            MsgBox "End Date Must be the Last of the Month"
        End If
    Else
        MsgBox "Invald End Date"
    End If
End Sub

Private Function getFirst(ByVal dt As Date) As Date
    getFirst = CDate(DatePart("m", dt) & "/1/" & DatePart("yyyy", dt))
End Function

Private Function getLast(ByVal dt As Date) As Date
    getLast = DateAdd("d", -1, DateAdd("m", 1, getFirst(dt)))
End Function

Is any how I can create Text2 automatically based on Text1?

carl_tawn,

That won't work if the Date in Text1 ISN'T the first of the month.

~IM

It should do.  Its simply working out the last day of whatever month is in Text1, irrespective of the day.

You are simply adding one month to whatever is in Text1.  So if you had 5 May 05, you would end up with 5 Jun 05.  Then you subtract one day which would be 4 Jun 05.

The add one month, subtract day algorithm only works if you start out with the first of the month.  See my example...

~IM

Oops, my mistake. I stand corrected :o)

But then again, I was answering the second part based on the assumption that Text1 would have been validated to ensure it was the start of the month.