<?php
class MinhaClasse

{

public $publica = 'A';
protected $protegida = 'B',
private $privada = 'C';

function imprimeAlo()

{

echo $this->publica;
echo $this->protegida;
echo $this->privada;

}

}
class MinhaClasse2 extends MinhaClasse
{

function, construct(){

$this->protegida = '_';

}
function imprimeAlo()
{

echo @$this->publica?: '*';
echo @$this->protegida?: '*';
echo @$this->privada 2?: '*';

}

}
$obj = new MinhaClasse();
$obj->imprimeAlo();
$obj2 = new MinhaClasse2();
$obi2->imprimeAlo();