Using Reflection to get private property value in PHP

reflection.php

<?php
 
class A {
    private $data;
 
    public function setData($value)
    {
        $this->data = $value;
    }
}
 
$a = new A;
$a->setData('hello world');

#echo $a->data; //error
 
$reflector = new ReflectionClass('A');
$properties = $reflector->getProperties();
 
foreach ($properties as $property) {
    $property->setAccessible(true);
    echo $property->getValue($a) . PHP_EOL; // hello world
    #$property->setAccessible(false);
    #echo $property->getValue($a) . PHP_EOL; // error
}