Listing mengurutkan dengan pointer

program pointer;
uses crt;
type tree = ^ptr;
     ptr = record
       data : char;
       ki,ka: tree;
end;

var br,p :tree;
    x     : char;

    procedure tam(var p,br:tree);
    begin
         if p = Nil then
            p:= br
         else
             if p^.data > br^.data then
                tam (p^.ka,br)
             else
                tam (p^.ki,br);
         end;
    procedure lihat (var p:tree);
    begin
         if p<> Nil then
            begin
                 lihat (p^.ka);
                 write (p^.data:4);
                 lihat (p^.ki);
            end;
         end;

    Begin
    clrscr;
         new(p); p:=Nil;
         repeat
               write('Maukkan Data : '); readln(x);
               if x <> 'x' then
               begin
                    new(br);
                    br^.ki :=Nil;
                    br^.ka :=Nil;
                    br^.data:=x;
                    tam(p,br);
               end;
         until x = 'x';
         writeln;
         lihat(p);
         readln;
    end.