string dateDiff = null;
//获取当前时间

DateTime DateTime1 = DateTime.Now;

//第二天的0点00分00秒

DateTime DateTime2 = DateTime.Now.AddDays().Date;
//把2个时间转成TimeSpan,方便计算

TimeSpan ts1 = new TimeSpan(DateTime1.Ticks);

TimeSpan ts2 = new TimeSpan(DateTime2.Ticks);

//时间比较，得出差值

TimeSpan ts = ts1.Subtract(ts2).Duration();
//结果

dateDiff = ts.Days.ToString() + "天" + ts.Hours.ToString() + "小时" + ts.Minutes.ToString() + "分钟" + ts.Seconds.ToString() + "秒";