Online PHP editor | output for Zp59M

<?php abstract class Vehicle { protected static $wheels = 4; public function wheels() { return get_class($this) . " has " . static::$wheels . " wheels\n"; } } class Bike extends Vehicle { protected static $wheels = 2; } class Car extends Vehicle { protected static $wheels = 4; } class Car_With_Trailer extends Car { protected static $wheels = 6; } $bike = new Bike(); $car = new Car(); $car_with_trailer = new Car_With_Trailer(); print $car->wheels(); print $bike->wheels(); print $car_with_trailer->wheels();