PHP Class not found but it's in folder and it is also included

Question

I'v a singular proble... if I include files in this manner:

<?php     
    session_start();
    session_regenerate_id();
    foreach (glob("../class/*.php") as $filename)
    {
        echo "$filename\n";
        include $filename;
    }
    foreach (glob("../utilities/*.php") as $filename) {
        echo "$filename\n";
        include $filename;
    }

class ECommerce {
    private $checker;
    private $errorManager;

    /**
     * ECommerce constructor.
     */
    function __construct() {
        $this->checker = new Checker();
        $this->errorManager = new ErrorManager();
    }

the website doesn't work and when I do

$ecommerce = new ECommerce();

it says that

Class 'ErrorManager' not found in path

I thought anything, when I'v thought to try this:

 <?php     
    session_start();
    session_regenerate_id();
    include "../class/Checker.php";
    include "../class/User.php";
    include "../utilities/ErrorManager.php";

class ECommerce {
    private $checker;
    private $errorManager;

    /**
     * ECommerce constructor.
     */
    function __construct() {
        $this->checker = new Checker();
        $this->errorManager = new ErrorManager();
    }

in this manner, it works and anything does what it has to do!
Inside me, the question "why", has made roots and I can't sleep (really).
Why first manner works for all classes except for ErrorManager?
Thank you before!

Here, there is ErrorManager class code (it has the blank construct like Checker class)

<?php
class ErrorManager
{
function __construct() {
}

function getErrorUserNameNotValid() {
    return "Nome inserito non valido";
}

function getErrorUserSurnameNotValid() {
    return "Cognome inserito non valido";
}

function getErrorUserEmailAlreadyExists() {
    return "Email inserita non valida!";
}

function getErrorUserEmailNotValid() {
    return "Email inserita non valida!";
}

function getErrorUserPasswordNotValid() {
    return "Password inserita non valida! Inserisci una password che sia lunga tra i 6 e i 50 caratteri!";
}

function getErrorUserAddressNotValid() {
    return "Indirizzo inserito non valido!";
}

function getErrorUserPhoneNumberNotValid() {
    return "Numero telefonico inserito non valido! Inserisci solo numeri, senza trattini o caratteri speciali!";
}
}

I include a screenshot of folder too

I'm trying this now, with AutoLoader:
This is in ECommerce class:

spl_autoload_register('MyAutoloader::ClassLoader');
spl_autoload_register('MyAutoloader::LibraryLoader');

And this is in MyAutoloaderClass

class MyAutoloader
{
public static function ClassLoader($className)
{
    $path = "../class/";
    include $path.$className.'.php';
}


public static function LibraryLoader($className)
{

    $path = __DIR__."/";
    include $path.$className.'.php';
}

}

It says that

include(../class/ErrorManager.php): failed to open stream: No such file or directory in

Answer 1

include on a relative path will search the file based on the path of the called PHP script, not the included PHP file your are calling include from.

To be able to include even if your ECommerce class is used from different locations, try

include __DIR__ . '/' . $filename;

On older PHP versions you can use dirname(__FILE__) instead of __DIR__.

There might be other dependencies before ErrorManager.php gets loaded, e.g. in Dispatcher.php.

What happens if you test the following?

include "../class/Checker.php";
include "../class/User.php";
include "../utilities/Dispatcher.php";
include "../utilities/ErrorManager.php";

Consider to use a class loading mechanism like spl_autoload_register. It makes the class dependency management much easier.