//出丑了,刚才没看清楼主的要求
procedure TForm1.Button1Click(Sender: TObject);
var
   buf:array[0..100] of char;
   a:byte;
begin
   fillmemory(@buf,101,0);
   a:=sendmessage(listbox1.handle,lb_getcount,0,0);
   sendmessage(listbox1.handle,lb_gettext,0,longint(@buf));
   showmessage('共'+inttostr(a)+'行,第0行是'+buf);
end;