.net中用DropDownList选择日期（vb代码）

看了别人写的C#的 自己转了一下 然后后重新改了改 写成了这个
另外还有一个我写的验证日期是否合法的代码 在后面 都是vb的 c#只会看不会写
  '判断闰年=======================
Private Function CheckLeap(ByVal year As Integer) As Boolean
If (year Mod 4 = 0) AndAlso (year Mod 100 <> 0) OrElse (year Mod 400 = 0) Then
Return True
Else
Return False
End If
End Function
'判断闰年结束=======================
'绑定每月的天数=====================
Private Sub BindDays(ByVal year As Integer, ByVal month As Integer)
Dim i As Integer
Dim AlDay As New ArrayList()
Select Case month
Case 1, 3, 5, 7, 8, 10, 12
For i = 1 To 31
AlDay.Add(i)
Next
'Exit Select
Case 2
If CheckLeap(year) Then
For i = 1 To 29
AlDay.Add(i)
Next
Else
For i = 1 To 28
AlDay.Add(i)
Next
End If
'Exit Select
Case 4, 6, 9, 11
For i = 1 To 30
AlDay.Add(i)
Next
'Exit Select
End Select
DropDownList_day.DataSource = AlDay
DropDownList_day.DataBind()
End Sub
'绑定每月的天数结束=====================
'页面上拖三个DropDownList DropDownList_year DropDownList_month DropDownList_day 都要autopostback
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim AlYear As New ArrayList()
Dim i As Integer
For i = 1940 To 1992
AlYear.Add(i)
Next
Dim AlMonth As New ArrayList
For i = 1 To 12
AlMonth.Add(i)
Next
If Not Me.IsPostBack Th