update(t)
   struct xronos *t;
{
      t->seconds++;
      if(t -> seconds = = 60) 
       {
             t->seconds=0;
             t->minutes++;
        }
      if (t -> minutes = = 60) 
       {
             t -> minutes=0;
                         t -> hours++;
                     }
                  if( t-> hours = = 24) t -> hours=0;
                    delay( );
              }