时间（差和）的计算

        DateTime start =DateTime.Now;
        DateTime end = start.AddDays(60);
        var kk = "2012-9-15 0:00:00";
        TimeSpan bb = Convert.ToDateTime(DateTime.Now).Subtract(Convert.ToDateTime(kk));
        string sd = bb.ToString();
        int num=sd.IndexOf(".");
        string numtim =sd.Substring(0, num);
        label.Text = Convert.ToInt32(numtim).ToString();
        label.Text +="天，相加="+ end;