What are some common debugging techniques for identifying issues with session variables in PHP?

One common issue with session variables in PHP is that they may not be set or retained across pages as expected. To debug this, you can start by checking if the session is started properly and if the session variables are being set and accessed correctly. Additionally, you can use functions like session_start(), session_id(), and session_status() to troubleshoot any session-related problems.

<?php
// Start the session
session_start();

// Set a session variable
$_SESSION['username'] = 'JohnDoe';

// Check if the session variable is set
if(isset($_SESSION['username'])) {
    echo 'Session variable is set: ' . $_SESSION['username'];
} else {
    echo 'Session variable is not set';
}
?>