C#里面时间操作

1。比较时间大小的实验   
      string   st1="12:13";   
        string   st2="14:14";   
        DateTime   dt1=Convert.ToDateTime(st1);   
        DateTime   dt2=Convert.ToDateTime(st2);   
        DateTime   dt3=DateTime.Now;   
        if(DateTime.Compare(dt1,dt2)>0)   
          msg.Text=st1+">"+st2;   
        else   
          msg.Text=st1+"<"+st2;   
        msg.Text+="/r/n"+dt1.ToString();   
        if(DateTime.Compare(dt1,dt3)>0)   
          msg.Text+="/r/n"+st1+">"+dt3.ToString();   
        else   
          msg.Text+="/r/n"+st1+"<"+dt3.ToString();   
    
  2。计算两个时间差值的函数，返回时间差的绝对值：   
                  private   string   DateDiff(DateTime   DateTime1,DateTime   DateTime2)   
                  {   
                          string   dateDiff=null;   
                          try   
                          {   
                                  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";   
                          }   
                          catch   
                          {   
    
                          }   
                          return   dateDiff;   
                  }   
    
  3。实现计算DateTime1－36天＝DateTime2的功能   
    
        TimeSpan   ts=new   TimeSpan(40,0,0,0);   
        DateTime   dt2=DateTime.Now.Subtract(ts);   
        msg.Text=DateTime.Now.ToString()+"-"+ts.Days.ToString()+"天/r/n";   
        msg.Text+=dt2.ToString();