获取两个日期之间相差的周数

/// <summary>
/// 获取两个日期之间相差的周数
/// </summary>
/// <param name="dt1"></param>
/// <param name="dt2"></param>
/// <returns></returns>
private int GetWeekInBTime(DateTime dt1, DateTime dt2)
{
TimeSpan ts = dt1 - dt2;
DateTime dt = ts.TotalDays > 0 ? dt1 : dt2;
int days = (int)System.Math.Abs(ts.TotalDays) + (7 - ((int)dt.DayOfWeek + 1));

return days / 7 + (days % 7 == 0 ? 0 : 1);
}