如何将字符串变量与日期变量进行比较

Question

   Dim strLastDate as string ' fill this value from database field 
   Dim TodayDate as Date = Format(Now.Date, "dd/MM/yyyy")

• 这里

  strLastDate = "16/07/2014 04:39:10"

  和

  TodayDate =17/07/2014"

• 如何比较这些日期？根据结果​​，我必须显示警告。

Answer 1

 Private Sub CompareDates(ByVal strLastDate As String)
    'as you said strLastDate is getting from database 
    'lets assume strLastDate = "16/07/2014 04:39:10"
    Dim dteToday As Date = CDate(Format(Now.Date, "dd/MM/yyyy"))
    Dim dateDiffer As Integer
    Dim dteLastdate As Date
    'formats the strLastDate like "dd/MM/yyyy"
    strLastDate = strLastDate.Substring(0, 10) 'you'll get 16/07/2014
    'converts string to date 
    dteLastdate = CDate(strLastDate)
    'now Compare  dteToday with dteLastdate
    dateDiffer = dteToday.Subtract(dteLastdate).TotalDays
    If dateDiffer > 2 Then
        'your alert message is here
    End If
End Sub