WinForm(C#)倒计时（年月日时分秒）

     public   partial   class  FormTime : Form
    {
         public  FormTime()
        {
            InitializeComponent();
        }

         private   void  FormTime_Load( object  sender, EventArgs e)
        {
            timerMain.Enabled  =   true ;
            timerMain.Interval  =   1000 ;
            timerMain.Start();
        }

         private   void  timerMain_Tick( object  sender, EventArgs e)
        {
            DateTime observeTime  =  DateTime.Parse( " 2023-11-22 22:45:30 " ); // 倒计时日期
            DateTime now  =  DateTime.Now;     // 当前时间
            TimeSpan ts  =  observeTime.Subtract(now);     // 两个时间之差
            StringBuilder result = new  StringBuilder();    // 存放结果
             int  year = observeTime.Year  -  now.Year;        // 得到相差的年
             int  month  =  observeTime.Month  -  now.Month;   // 得到相差的月
             int  day  =  observeTime.Day  -  now.Day;         // 得到相差的日

             int  hmh = (observeTime.Hour - now.Hour) * 3600 + (observeTime.Minute - now.Minute) * 60 + (observeTime.Second - now.Second);

             // 如果时分秒比现在的时间晚
             if (hmh <= 0 )
            {
                 // 向日借一
                day -- ;
                 if ((day <= 0 && month > 0 ) || (day <= 0 && year > 0 ))
                {
                     // 如果天数小于0向月借一
                    day = GetDay(now.Year, now.Month) -  now.Day  +  observeTime.Day;
                    month -- ;
                     if (month < 0 && year > 0 )
                    {
                         // 如果月数小于0，向年借一，同时把月专为正数
                        month  +=   12 ;
                        year -- ;
                    }
                }
            }


             // 如果天数小于0向月借一
             if  ((day  <   0   &&  month  >   0 )  ||  (day  <   0   &&  year  >   0 ))
            {
                day  =  GetDay(now.Year, now.Month)  -  now.Day  +  observeTime.Day;
                month -- ;
                 if  (month  <   0   &&  year  >   0 )
                {
                     // 如果月数小于0，向年借一，同时把月专为正数
                    month  +=   12 ;
                    year -- ;
                }
            }

             // 如果月数小于0，向年借一，同时把月专为正数
             if  (month  <   0   &&  year  >   0 )
            {
                month  +=   12 ;
                year -- ;
            }

             if  (year < 0 || (year  ==   0   &&  month  <   0 ) || (year  ==   0   &&  month == 0 && day < 0 ))
            {
                lblShow.Text  =   " 已超过日期 " ;
                 return ;
            }

             if  (year >   0 )
            {
                result.Append(year +   " 年 " );
            }
             if  (month >   0 )
            {
                result.Append(month +   " 月 " );
            }
             if  (day >   0 )
            {
                result.Append(day +   " 天 " );
            }
             if  (ts.Hours  >   0 )
            {
                result.Append(ts.Hours  +   " 时 " );
            }
             if  (ts.Minutes  >   0 )
            {
                result.Append(ts.Minutes  +   " 分 " );
            }
             if  (ts.Seconds  >   0 )
            {
                result.Append(ts.Seconds  +   " 秒 " );
            }
             if (result.Length == 0 )
            {
                result.Append( " 已超过日期 " );
            }
            lblShow.Text  =  result.ToString();
        }

         // 输入月份后获得该月天数
         private   int  GetDay( int  year,  int  month)
        {
             int  result  =   31 ;
             switch  (month)                           
            {
                 case   4 :
                 case   6 :
                 case   9 :
                 case   11 :
                    result  =   30 ;
                     break ;
                 case   2 :
                     if  ((year  %   100   !=   0 )  &&  (year %   4   ==   0 )  ||  (year %   400   ==   0 ))
                    {
                        result  =   29 ;
                    }
                     else
                    {
                        result  =   28 ;
                    }
                     break ;
            }
             return  result;
        }
    }