PHP Classes and Objects

PHP supports Object-Oriented Programming (OOP), which allows you to structure your code using classes and objects. This makes your code more organized, reusable, and scalable.

🔹 What Are Classes & Objects?

Think of a class as a blueprint for creating objects. It defines properties (variables) and methods (functions) that objects of that class can use. An object is an instance of a class, meaning it’s like an actual car built from a blueprint.

Let’s look at a simple example! 🚗

📝 Example 1: Creating a Class & Object

Here’s how to define a class and create an object in PHP:

<?php
// Define a class
class Car {
    public $brand; // Property

    // Method to set the brand name
    function setBrand($name) {
        $this->brand = $name;
    }

    // Method to get the brand name
    function getBrand() {
        return $this->brand;
    }
}

// Create an object (instance of the class)
$myCar = new Car();
$myCar->setBrand("Tesla");

echo "My car brand is: " . $myCar->getBrand();
?>

Here, we created a Car class with a brand property and two methods: setBrand() to set the brand name and getBrand() to retrieve it. Then, we created an object of the Car class and assigned it a brand name.

📝 Example 2: Constructor Method

A constructor is a special method that gets automatically called when an object is created. We use __construct() in PHP to define a constructor.

<?php
class Animal {
    public $name;

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

    function getName() {
        return "This is a " . $this->name;
    }
}

// Creating objects with a constructor
$cat = new Animal("Cat");
$dog = new Animal("Dog");

echo $cat->getName(); // Output: This is a Cat
echo "<br>";
echo $dog->getName(); // Output: This is a Dog
?>

Whenever we create an object of the Animal class, the constructor automatically assigns the name.

🔹 Class Properties: Public, Private, and Protected

Properties in a class can have different access levels:

• public – Can be accessed from anywhere.
• private – Can only be accessed inside the class.
• protected – Can be accessed inside the class and in child classes.

Let’s see an example:

<?php
class Person {
    public $name; // Public property
    private $age; // Private property

    function __construct($personName, $personAge) {
        $this->name = $personName;
        $this->age = $personAge;
    }

    // Public method to access private property
    function getAge() {
        return "Age: " . $this->age;
    }
}

$john = new Person("John", 25);
echo "Name: " . $john->name;
echo "<br>";
echo $john->getAge(); // Allowed (accesses private property through method)
// echo $john->age; // ERROR: Cannot access private property
?>

The $age property is private, so it cannot be accessed directly from outside the class.

📝 Example 3: Inheritance (Extending a Class)

In inheritance, one class can inherit the properties and methods of another class using the extends keyword.

<?php
// Parent class
class Vehicle {
    protected $type;

    function setType($vehicleType) {
        $this->type = $vehicleType;
    }

    function getType() {
        return "Vehicle Type: " . $this->type;
    }
}

// Child class
class Bike extends Vehicle {
    function ride() {
        return "Riding a " . $this->type;
    }
}

$myBike = new Bike();
$myBike->setType("Motorcycle");

echo $myBike->getType(); // Output: Vehicle Type: Motorcycle
echo "<br>";
echo $myBike->ride(); // Output: Riding a Motorcycle
?>

Here, the Bike class inherits the properties and methods of the Vehicle class.

🎯 Key Takeaways

• A class is a blueprint, and an object is an instance of a class.
• Use constructors to automatically initialize object properties.
• Control access to class properties with public, private, and protected visibility.
• Use inheritance to extend class functionality.

📝 Practice Time!

Try modifying the examples to create your own custom classes. Maybe a Fruit class 🍎 or a Laptop class 💻? Have fun experimenting! 🚀