CodeIgniter4/public/index.php

<?php

// Path to the front controller (this file)
define('FCPATH', __DIR__ . DIRECTORY_SEPARATOR);

/*
 *---------------------------------------------------------------
 * BOOTSTRAP THE APPLICATION
 *---------------------------------------------------------------
 * This process sets up the path constants, loads and registers
 * our autoloader, along with Composer's, loads our constants
 * and fires up an environment-specific bootstrapping.
 */

// Ensure the current directory is pointing to the front controller's directory
chdir(FCPATH);

// This is the line that might need to be changed, depending on your folder structure.
$pathsConfig = FCPATH . '../app/Config/Paths.php';
// ^^^ Change this line if you move your application folder

// Load our paths config file
require $pathsConfig;

$paths = new Config\Paths();

// Location of the framework bootstrap file.
$bootstrap = rtrim($paths->systemDirectory, '\\/ ') . DIRECTORY_SEPARATOR . 'bootstrap.php';

require $bootstrap;

/*
 * ---------------------------------------------------------------
 * GRAB OUR CODEIGNITER INSTANCE
 * ---------------------------------------------------------------
 *
 * The CodeIgniter class contains the core functionality to make
 * the application run, and does all of the dirty work to get
 * the pieces all working together.
 */
$app = Config\Services::codeigniter();
$app->initialize();
$context = is_cli() ? 'php-cli' : 'web';
$app->setContext($context);

/*
 *---------------------------------------------------------------
 * LAUNCH THE APPLICATION
 *---------------------------------------------------------------
 * Now that everything is setup, it's time to actually fire
 * up the engines and make this app do its thang.
 */
$app->run();