C#计时器关键代码

//定义日期        private DateTime datetime = DateTime.Parse("2010-09-30 20:42:00");

        private void tmr_Tick(object sender, EventArgs e)        {            //判断日期是否已经到了            if (datetime < DateTime.Now)            {                this.tmrNow.Enabled = false;                this.txtTime.Text = "时间到了!";

            }            else            {                //计算时差                TimeSpan ts = this.datetime - DateTime.Now;

　　　　//整理格式,显示                this.txtTime.Text = ts.Days.ToString().PadLeft(2, '0') + "天"                     + ts.Hours.ToString().PadLeft(2, '0') + ":"                     + ts.Minutes.ToString().PadLeft(2, '0') + ":"                         + ts.Seconds.ToString().PadLeft(2, '0');            }        }