Challenge 1 — Solution

Task: Create an Animal class with a constructor setting $name, and a
method makeSound() that echoes a generic message. Create Cat and Cow
classes that extend it and override makeSound() with their own sound.
Create one of each and call makeSound() on both.

<?php
    class Animal {
        public function __construct(protected string $name) {}

        public function makeSound() {
            echo "{$this->name} makes some generic animal sound.<br>";
        }
    }

    class Cat extends Animal {
        public function makeSound() {
            echo "{$this->name} says Meow!<br>";
        }
    }

    class Cow extends Animal {
        public function makeSound() {
            echo "{$this->name} says Moo!<br>";
        }
    }

    $cat = new Cat("Whiskers");
    $cow = new Cow("Bessie");

    $cat->makeSound();
    $cow->makeSound();
?>


Output:
Whiskers says Meow!
Bessie says Moo!

Notes:
- Both Cat and Cow extend Animal, inheriting its constructor (via the
  protected $name property) without needing to redeclare it themselves.
- Each subclass overrides makeSound() with its own version - PHP always
  uses the most specific override available for the object a method is
  called on, so $cat->makeSound() runs Cat's own version, not Animal's
  generic one.
- $name is declared protected (rather than private) specifically so
  that Cat and Cow, as subclasses, can reference $this->name directly
  inside their own overridden makeSound() methods - a private property
  on Animal would not be accessible from a subclass at all.