In what situations should PHP developers consider using third-party authentication libraries or classes to handle user logins and sessions instead of writing custom scripts?

PHP developers should consider using third-party authentication libraries or classes when they need to implement secure user logins and sessions quickly and efficiently. These libraries often come with built-in security features, such as encryption and protection against common attacks like SQL injection and cross-site scripting. By using a trusted third-party library, developers can save time and ensure that their authentication system is robust and reliable.

// Example of using the PHP library "PHPAuth" for user authentication

require_once 'vendor/autoload.php';

$auth = new PHPAuth\Auth('mysql:host=localhost;dbname=database', 'username', 'password');

if($auth->isLogged()) {
    echo 'User is logged in';
} else {
    echo 'User is not logged in';
}