Hàm khởi tạo (__construct)

<?php
class Dog {
    public $name;
    public $breed;

    public function __construct($name, $breed) {
        $this->name = $name;
        $this->breed = $breed;
    }
}

$rex = new Dog("Rex", "German Shepherd");
$buddy = new Dog("Buddy", "Golden Retriever");

echo $rex->name . "\n";
echo $rex->breed . "\n";
echo $buddy->name . "\n";
echo $buddy->breed . "\n";

Rex
German Shepherd
Buddy
Golden Retriever

class Cat {
    public $name;
    public $age;

    public function __construct($name, $age = 1) {
        $this->name = $name;
        $this->age = $age;
    }
}

$fluffy = new Cat("Fluffy", 3);
$whiskers = new Cat("Whiskers");  // age mặc định là 1

echo $fluffy->name . " is " . $fluffy->age . " years old\n";
echo $whiskers->name . " is " . $whiskers->age . " years old\n";

Fluffy is 3 years old
Whiskers is 1 years old