C#的DateDiff方法，返回两个时间所相差的Second,Minute,Hour,Day,Week,Month,Quarter,Year

public enum DateInterval
{
   Second,Minute,Hour,Day,Week,Month,Quarter,Year
}

public static long DateDiff(DateInterval Interval,System.DateTime StartDate,System.DateTme EndDate)
{
   long lngDateDiffValue=0;
   System.TimeSpan TS=new System.TimeSpan(EndDate.Ticks-StartDate.Ticks);
  switch(Interval)
{
   case DateInterval.Second:
      lngDateDiffValue=(long)TS.TotalSeconds;
      break;
   case DateInterval.Minute:
     lngDateDiffValue=(long)TS.TotalMinutes;
     break;
   case DateInterval.Hour:
     lngDateDiffValue=(long)TS.TotalHours;
     break;
   case DateInterval.Day:
    lngDateDiffValue=(long)TS.Days;
    break;
   case DateInterval.Week:
     lngDateDiffValue=(long)(TS.Days/7);
     break;
   case DateInterval.Month:
    lngDateDiffValue=(long)(TS.Days/30);
    break;
    case DateInterval.Quarter:
    lngDateDiffValue=(long)((TS.Days/30)/3);
    break;
    case DateInterval.Year:
     lngDateDiffValue=(long)(TS.Days/365);
    break;
}
 return (lngDateDiffValue);
}