function search( key : typekey; var r : dataarray ) : integer;
     var high, j, low : integer;

     begin
     low := 0;
     high := n;
     while high-low > 1 do begin
          j := (high+low) div 2;
          if key <= r[j].k then high := j
                           else low  := j
          end;
     if r[high].k = key then search := high  {*** found(r[high]) ***}
                        else search := -1;   {*** notfound(key) ***}
     end;