理解如何在php中引用父类的问题

class ParentClass {
    protected $name = "Parent";
}

class ChildClass extends ParentClass {
    public function getParentName() {
        return $this->name; // 访问子类继承的父类属性
    }
}

$child = new ChildClass();
echo $child->getParentName(); // 输出 "Parent"

class ParentClass {
    protected function sayHello() {
        echo "Hello from Parent";
    }
}

class ChildClass extends ParentClass {
    public function callParentMethod() {
        parent::sayHello(); // 调用父类的方法
    }
}

$child = new ChildClass();
$child->callParentMethod(); // 输出 "Hello from Parent"