php--inheritance

inheritance Using keywords:extends
PHP is single-inheritance, and there is only one parent class
The constructor of PHP can be inherited, but if the subclass also defines a constructor, the parent class is overwritten

Subclasses define the functions of the parent class, called overriding

The parent keyword, which is intended to be a parent, is currently the object of the parent class of the current class in the child class.
Use it to invoke the properties and behavior of the overridden parent class

Class animal{

    Public $name;
    Public $sex;
    Public $age;

    Public function __construct ($name)
    {
        $this->name = $name;
    }

    Public function shout () {
        echo  ' Animals all have their own cries ';
    }

    Public Function desc () {

    }
}

Class Dog extends animal{

Public    function __construct ($name)
//    {
        $this->name = $name;
//    }

    /**
     * Subclasses define the functions of the parent class, called Overrides
     */
    Public function shout () {

        Echo ', Dog's cry: Wang ~ ~ Wang ~ Wang ~;
    }

    Public Function desc () {
        Echo ' Dog's name: '. $this->name;
        parent::shout ();
        $this->shout ();
    }
}

Class Cat extends animal{

Public    function __construct ($name)
//    {
        $this->name = $name;
//    }

    Public function shout () {
        Echo ', the cat's cry: Meow ~ ~ Meow ~ ~ ~;
    }
    Public Function desc () {
        Echo ' Meow's name: '. $this->name;
        $this->shout ();
    }
}

$animal = new Dog (' blessings ');
$animal->desc ();

Echo ' <br><br> ';

$animal = new Cat (' Mimi ');
$animal->desc ();

php--inheritance