深入理解PHP中的多态性特性

// 定义一个接口Shape
interface Shape {
    public function calculateArea();
}

// 定义一个矩形类Rectangle实现Shape接口
class Rectangle implements Shape {
    private $width;
    private $height;
    
    public function __construct($width, $height) {
        $this->width = $width;
        $this->height = $height;
    }
    
    public function calculateArea() {
        return $this->width * $this->height;
    }
}

// 定义一个圆形类Circle实现Shape接口
class Circle implements Shape {
    private $radius;
    
    public function __construct($radius) {
        $this->radius = $radius;
    }
    
    public function calculateArea() {
        return 3.14 * pow($this->radius, 2);
    }
}

// 使用多态性调用不同的calculateArea方法
function printArea(Shape $shape) {
    echo "The area is: " . $shape->calculateArea() . "
";
}

// 创建矩形对象并打印面积
$rectangle = new Rectangle(5, 10);
printArea($rectangle);

// 创建圆形对象并打印面积
$circle = new Circle(5);
printArea($circle);