计算两个日期之间的天数

/// <summary>
    /// 计算两个日期的时间间隔
    /// </summary>
    /// <param >第一个日期和时间</param>
    /// <param >第二个日期和时间</param>
    /// <returns></returns>
    private string DateDiff(DateTime DateTime1, DateTime DateTime2)
    {
        string dateDiff = null;

        TimeSpan ts1 = new TimeSpan(DateTime1.Ticks);
        TimeSpan ts2 = new TimeSpan(DateTime2.Ticks);
        TimeSpan ts = ts1.Subtract(ts2).Duration();
        //dateDiff = ts.Days.ToString() + "天"+ ts.Hours.ToString() + "小时" + ts.Minutes.ToString() + "分钟"+ ts.Seconds.ToString() + "秒";
        dateDiff = Convert.ToString(ts.Days + 1) + "天";

        return dateDiff;
    }