PHP $_session is not work in wordpress

Question

why PHP $_session is not working in wordpress my php code is

session_start();
session_register('lang_opt');  
$_SESSION['lang_opt'] = $_POST['lang_opt'];
$mylang = $_SESSION['lang_opt']; 
echo $mylang;

Answer 1

Yes, you must use a small change for use session in WordPress.

if ( ! session_id() ) session_start();

Better you use a custom function

function my_start_session() {

@session_cache_limiter('private, must-revalidate'); //private_no_expire
@session_cache_expire(0);
@session_start();
}

*Please edit, I write from a mobile