./index.php 入口檔案
function __autoload($classname) {
    $filename = "./". $classname .".php";
    include_once($filename);
}

// we've called a class ***
$obj = new myClass();

//myClass.php
class myClass {
    public function __construct() {
        echo "myClass init'ed successfuly!!!";
    }
}

思考：其實自動載入就是省去自己手寫多個include_once檔案，讓複用自動載入函式引入需要include_once的檔案