Creating a config file in PHP

Question

I am working on creating config file for my PHP project. 

1-Use Variable

$config['hostname'] = "localhost";
$config['dbuser'] = "dbuser";
$config['dbpassword'] = "dbpassword";
$config['dbname'] = "dbname";
$config['sitetitle'] = "sitetitle";

2-Use Const

define('DB_NAME', 'test');
define('DB_USER', 'root');
define('DB_PASSWORD', '');
define('DB_HOST', 'localhost');
define('TITLE', 'sitetitle');

3-Use Database

Out of these 3 options which one should I choose?