I was working in a login system
session_is_registered
php5.4+
if (session_is_registered('id_user') == true && session_is_registered ('username') == true){}
if (isset($_SESSION['id_user']) && isset($_SESSION['username'])){}
if (!session_is_registered('id_user') || !session_is_registered('username')){}
!isset()
empty()
You can use like this way
if (isset($_SESSION['id_user']) && isset($_SESSION['username'])){
/* this will true if both are set */
}
if (!isset($_SESSION['id_user']) || !isset($_SESSION['username'])){
/* this will true if one of them is not set */
}
isset will give true if variable is set
empty will give true if variable is set and its blank or nullisset() is NOT equivalent to empty().