php中的类是什么有哪些

<?php
class Car {
    public $color;
    public $speed = 0;

    public function accelerate($amount) {
        $this->speed += $amount;
    }

    public function brake($amount) {
        $this->speed = max(0, $this->speed - $amount); // 保证速度不为负数，这是个小细节，但很重要
    }

    public function __construct($color) { // 构造函数，对象创建时自动调用
        $this->color = $color;
    }

    public function __destruct() { // 析构函数，对象销毁时自动调用，可以用来释放资源
        echo "Car {$this->color} is destroyed.\n";
    }
}

$myCar = new Car("red");
$myCar->accelerate(60);
echo "My car is {$myCar->color} and its speed is {$myCar->speed}.\n";
$myCar->brake(20);
echo "After braking, speed is {$myCar->speed}.\n";

// 对象销毁，会触发析构函数
unset($myCar);


//  另一个类，展示继承
class SportsCar extends Car {
    public $turbo = false;

    public function activateTurbo() {
        $this->turbo = true;
        echo "Turbo activated!\n";
    }
}

$sportsCar = new SportsCar("blue");
$sportsCar->activateTurbo();
$sportsCar->accelerate(100);
echo "Sports car speed: {$sportsCar->speed}\n";

?>