- session_start: documentation ( source)
<?php
session_start();
$loggedOutLink = '<a href="logout.php">Log out</a>';
$loggedInLink = '<a href="login.php">Log in</a>';
if (isset($_SESSION['isLoggedIn']) && $_SESSION['isLoggedIn'] === TRUE){
echo $loggedInLink;
} else {
echo $loggedOutLink;
}
?>