Compara dois arquivos textos

procedure TForm1.Button1Click(Sender: TObject);
var
       filename1 : string;
       filename2 : string;
begin
      filename1 := Edit1.Text;
      filename2 := Edit2.Text;
      compfile(filename1, filename2);
      showmessage('Veja o resultado no arquivo c:Tempdiff.txt');
end;
 
procedure tform1.compfile(filename1, filename2 : string);
var
     f1 : system.textfile;
     f2 : system.textfile;
     diff : system.textfile;
     buf1 : string;
     buf2 : string;
     l : integer;
begin
    assignfile(f1, filename1);
    assignfile(f2, filename2);
    assignfile(diff, 'c:Tempdiff.txt');
    reset(f1);
    reset(f2);
    rewrite(diff);
    l := 1;
   while not eof(f1) do begin
       readln(f1, buf1);
       readln(f2, buf2);
       if not (compstr(buf1, buf2) )then begin
           writeln(diff, 'line: '+ inttostr(l) + '-' + buf1);
           writeln(diff, 'line: '+ inttostr(l) + '-' + buf2);
           writeln(diff, ' ');
       end;
       inc(l);
   end;
   closefile(f1);
   closefile(f2);
   closefile(diff);
end;
 
function tform1.compstr(s1, s2 : string) : boolean;
var
     i : integer;
     btemp : boolean;
begin
     btemp := true;
     if (length(s1) <> length(s2)) then begin
         btemp := false;
     end{if}
     else begin
          for i:= 1 to length(s1) do begin
               if (s1[i] <> s2[i]) then begin
                   btemp := false;
                   exit;
               end;{if}
          end;{for}
     end;{else}
     result := btemp;
end;