How can debugging session-related issues in PHP code help identify login problems?

Session-related issues in PHP code can often lead to login problems, as sessions are commonly used to store and manage user login information. By debugging session-related problems, such as incorrect session variable values or expired sessions, developers can identify and resolve issues that may be preventing users from successfully logging in. One way to debug session-related problems is to check if the session variables are being set correctly and if they are being destroyed or unset when the user logs out.

// Start the session
session_start();

// Check if the session variables are being set correctly
if(isset($_SESSION['user_id'])) {
    // User is logged in
} else {
    // User is not logged in
}

// Destroy or unset the session variables when the user logs out
if(isset($_GET['logout'])) {
    session_unset();
    session_destroy();
}