Error including class in index file so I can’t instantiate it [PHP]

Question

Hello I have two file o INDEX.PHP which is located at the root of the project and the Archive SYSTEM.PHP which is located inside the folder LIB.

Summary of the Archive INDEX

<?php 
  define('APP_ROOT', 'home');
  require_once 'config/Bootstrap.php';
  require_once 'lib/System.php';
  $System = new System();
  $System->start();

Archive summary SYSTEM

<?php 
  namespace lib;
  require_once 'Router.php';
  class System extends Router {

   Aqui contem o method **START**

  }

php returns the following error: Fatal error: Uncaught Error: Class 'System' not found in 'My directory'

I already gave a var_dump exists_file in the INDEX direct path to the lib/System.php path and returned TRUE, the path is correct but because I can’t find the class?

Answer 1

Your class System belongs to the namespace lib and therefore its "full name" (or Fully-Qualified name) is lib\System. Therefore, to invoke it, you need to reference it by its "full name".

// ...
$System = new lib\System();

Or use aliases:

require_once 'caminho/para/arquivo.php';

use lib\System; 

$System = new System();

Or else,

require_once 'caminho/para/arquivo.php';

use lib\System as MyClass;

$System = new MyClass();