Why do I get "Warning: require_once(config): failed to open stream: No such file or directory" when trying to run this code?

Question

I'm currently working on programming my very own online store with NetBeans IDE 8.0.2 using PHP. My system is Windows 7 32bit and my localhost is powered by WampServer 2.5. I'm following THC Courses: https://www.youtube.com/playlist?list=PLbXVpMmmrntAvOYgkqhHW0hVu8dWUNyfz

So far everything was going great but I got stock at this video: S2 {Building Framework} Class and method (p6). The guy is asking to echo a sample text on the screen to test the code, but I get these two error messages when running the project on localhost:

Warning: require_once(config): failed to open stream: No such file or directory in C:\wamp\www\ecommerce\inc\autoload.php on line 2
Fatal error: require_once(): Failed opening required 'config' (include_path='.;C:\php\pear') in C:\wamp\www\ecommerce\inc\autoload.php on line 2

autoload.php:

<?php

    require_once('config');

    function __autoload($class_name) {

        $class = explode("_", $class_name);
        $path = implode("/", $class).".php";
        require_once($path);

    }

Core.php:

<?php

    class Core {

        public function run() {
            echo "Hello this is a print test";

        }

    }

index.php:

<?php

    require_once'inc/autoload.php';
    $core = new Core();
    $core->run();

config.php:

<?php

    if(!isset($_SESSION)) {
        session_start();

    }

    //site domain name with http
    defined("SITE_URL")
    ||define("SITE_URL", "http://".$_SERVER['SERVER_NAME']);

    //directory seperator
    defined("DS")
    ||define("DS", DIRECTORY_SEPERATOR);

    //root path
    defined("ROOT_PATH")
    ||define("ROOT_PATH", realpath(dirname(__FILE__) .DS.".." .DS));


    //classes folder
    defined("CLASSES_DIR")
    ||define("CLASSES_DIR", classes);

    //pages folder
    defined("PAGES_DIR")
    ||define("PAGES_DIR", pages);



    //modules folder
    defined("MOD_DIR")
    ||define("MOD_DIR", "mod");


    //inc folder
    defined("INC_DIR")
    ||define("INC_DIR", "inc");


    //templates folder
    defined("TEMPLATE_DIR")
    ||define("TEMPLATE_DIR", "template");

    //emails path
    defined("EMAILS_PATH")
    ||define("EMAILS_PATH", ROOTH_PATH.DS. "emails");

    //catalogue images path
    defined("CATALOGUE_PATH")
    ||define("CATALOGUE_PATH", ROOTH_PATH.DS. "media" .DS."catalogue");


    //add all above directories to the include path
    set_include_path(implode(PATH_SEPERATOR, array(
    realpath(ROOTH_PATH.DS.CLASSES_DIR),
    realpath(ROOTH_PATH.DS.PAGES_DIR),
    realpath(ROOTH_PATH.DS.MOD_DIR),
    realpath(ROOTH_PATH.DS.INC_DIR),
    realpath(ROOTH_PATH.DS.TEMPLATE_DIR).
    get_include_path()

    )));

Answer 1

Change this:

require_once('config');

to:

require_once('config.php');
                   //^^^See here file extension

(Also make sure it's in the same directory with autoload.php, otherwise change the path)

EDIT:

Or try i with a absolute path like this:

require_once(dirname(__FILE__) . "/config.php");

EDIT 2:

Since you now get error messages from the config file, means that it got included, but still has some errors in it!

The first would be this:

//directory seperator
defined("DS")
||define("DS", DIRECTORY_SEPERATOR);
             //^^^^^^^^^^^^^^^^^^^ Typo must be: DIRECTORY_SEPARATOR

Next one is here:

//classes folder
defined("CLASSES_DIR")
||define("CLASSES_DIR", classes);
                      //^^^^^^^ This isn't a constant so if it is a string put quotes around it

Same error here:

//pages folder
defined("PAGES_DIR")
||define("PAGES_DIR", pages);
                    //^^^^^

Next error here:

//emails path
defined("EMAILS_PATH")
||define("EMAILS_PATH", ROOTH_PATH . DS .  "emails");
                      //^^^^^^^^^^ Typo must be: ROOT_PATH , you have one h too much

Same here:

//catalogue images path
defined("CATALOGUE_PATH")
||define("CATALOGUE_PATH", ROOTH_PATH.DS. "media" .DS."catalogue");
                         //^^^^^^^^^^

And all over the palce you have 6 typos here:

//add all above directories to the include path
set_include_path(implode(PATH_SEPERATOR, array(
                       //^^^^^^^^^^^^^^ Typo must be: PATH_SEPARATOR 
realpath(ROOTH_PATH.DS.CLASSES_DIR),
       //^^^^^^^^^^ Typo must be: ROOT_PATH , you have one h too much
realpath(ROOTH_PATH.DS.PAGES_DIR),
       //^^^^^^^^^^
realpath(ROOTH_PATH.DS.MOD_DIR),
       //^^^^^^^^^^
realpath(ROOTH_PATH.DS.INC_DIR),
       //^^^^^^^^^^
realpath(ROOTH_PATH.DS.TEMPLATE_DIR).
       //^^^^^^^^^^
get_include_path()

)));

EDIT 3:

Here you can simplify these 2 lines and i would change the require, so it works even if you include the file itself into another one! Like this:

autoload.php:

function __autoload($class_name) {

    $class = explode("_", $class_name);
    $path = implode("/", $class).".php";
    require_once($path);

}

to this:

function __autoload($class_name) {

    $path = str_replace("_", "/", $class_name) . ".php";
    require_once(dirname(__FILE__) . "/" . $path);

}