PHP Autoloading Class Files

Summary: in this tutorial, you will learn how to organize your class files and load them automatically using PHP  __autoload() function.

It is good practice to keep each PHP class in a separated file and all class files in a folder named classes. In addition, Person class, the file name should be person.php.

the name of the class should be used to name the file for example if you have a

Before using a class you need to load it in your script file using PHP include file function such as  require_once() as follows:

1 2	require_once("classes/bankaccount.php"); $account = new BankAccount();

When the number of classes grows, it is quite tedious to call  require_once() function everywhere you use the classes. Fortunately, PHP provides a mechanism that allows you to load class files automatically whenever you try to create an object from a non-existent class in the context of the current script file.

PHP will call  __autoload() function automatically whenever you create an object from a non-existent class. To load class files automatically, you need to implement the __autoload() function somewhere in your web application as follows:

1 2 3 4 5

<?php function __autoload($className) { $className = str_replace('..', '', $className); require_once("classes/$className.php"); }

Whenever you create an object from a non-existent class, PHP looks into the  ./classes folder and load the corresponding class file using the  require_once() function.

From now on, you don’t have to call  require_once() function every time you use the class, which is very useful.

Notice that if PHP cannot find the __autoload() function or if the  __autoload() function failed to load the class files, you will get an error message.