PHP Constructors

In PHP, a constructor is a special method that is automatically called when an object is created. It allows you to initialize object properties at the time of object creation.

The constructor method in PHP is named __construct().

🔹 Why Use Constructors?

Imagine ordering a pizza 🍕, and it arrives with no toppings—you have to add them manually every time. Annoying, right? A constructor helps you automatically set values when an object is created, so you don’t have to do it manually.

📝 Example 1: Using a Constructor

Let’s create a Car class where the brand name is set automatically using a constructor.

<?php
class Car {
    public $brand;

    // Constructor method
    function __construct($name) {
        $this->brand = $name;
    }

    function getBrand() {
        return "Car Brand: " . $this->brand;
    }
}

// Creating objects with constructor
$car1 = new Car("Tesla");
$car2 = new Car("BMW");

echo $car1->getBrand(); // Output: Car Brand: Tesla
echo "<br>";
echo $car2->getBrand(); // Output: Car Brand: BMW
?>

As soon as we create a new Car object, the constructor automatically assigns the brand name. No need for a separate method to set it!

📝 Example 2: Constructor with Default Values

If no brand is specified, we can set a default value in the constructor.

<?php
class Laptop {
    public $brand;

    function __construct($name = "Unknown") {
        $this->brand = $name;
    }

    function getBrand() {
        return "Laptop Brand: " . $this->brand;
    }
}

// Creating objects with and without parameters
$laptop1 = new Laptop("Dell");
$laptop2 = new Laptop(); // No brand specified

echo $laptop1->getBrand(); // Output: Laptop Brand: Dell
echo "<br>";
echo $laptop2->getBrand(); // Output: Laptop Brand: Unknown
?>

Since we didn’t pass a value for $laptop2, it gets the default value "Unknown".

🔹 Using Multiple Parameters in a Constructor

Constructors can take multiple arguments to initialize multiple properties.

📝 Example 3: Constructor with Multiple Parameters

<?php
class Mobile {
    public $brand;
    public $price;

    function __construct($name, $cost) {
        $this->brand = $name;
        $this->price = $cost;
    }

    function getDetails() {
        return "Mobile: " . $this->brand . " - Price: $" . $this->price;
    }
}

// Creating objects
$phone1 = new Mobile("iPhone", 999);
$phone2 = new Mobile("Samsung", 799);

echo $phone1->getDetails();
echo "<br>";
echo $phone2->getDetails();
?>

Now each object has both brand and price properties set automatically.

🔹 Using Constructors in Inheritance

When a child class extends a parent class, it can inherit or override the constructor.

📝 Example 4: Constructor in an Inherited Class

<?php
class Animal {
    public $name;

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

    function getName() {
        return "Animal: " . $this->name;
    }
}

// Child class
class Dog extends Animal {
    public $breed;

    function __construct($animalName, $dogBreed) {
        parent::__construct($animalName); // Calling parent constructor
        $this->breed = $dogBreed;
    }

    function getBreed() {
        return "Breed: " . $this->breed;
    }
}

$dog1 = new Dog("Dog", "Labrador");
echo $dog1->getName();
echo "<br>";
echo $dog1->getBreed();
?>

The Dog class calls the parent class constructor using parent::__construct(), so it gets the name from the Animal class and adds its own breed property.

🎯 Key Takeaways

• __construct() is a special method that runs when an object is created.
• Constructors help initialize object properties automatically.
• Default values can be set if no arguments are passed.
• Multiple parameters can be used to initialize multiple properties.
• Child classes can inherit or override parent class constructors.

📝 Practice Time!

Try modifying the examples to create your own Book 📖 or Movie 🎬 classes with constructors. Have fun experimenting! 🚀