Classes and Objects

Classes and objects are some of the key concepts of OOP in PHP. Understanding these concepts will give you the ability to structure your code in such a way that it becomes easier to maintain and also extend.

In this tutorial, we will dive into the basics of classes and objects as used in PHP, using examples whenever appropriate to help illustrate each concept.

What is a Class in PHP?

In PHP, a class is like a mold with two main parts: attributes, which describe what something is like, and methods, which describe what it can do. You can think of a class as a template or mold for making objects of the same kind. Just as a mold can be used to create many items with the same shape, a class lets you make many objects with the same features. The class itself is just a design—it doesn’t hold any real data until you create objects from it.

Here is an example of a basic class in PHP:

class Car {
    public $color;
    public $model;
    public function startEngine() {
        return "Engine started!";
    }
}

Above, the class Car contains two properties: $color and $model, and one method, startEngine(). This class provides a template to create car objects. Each one of these would contain its color and model and a way to start its engine.  

What is an Object in PHP?

An object is a specific version created from a class. When you make an object, you're using the class blueprint to build an example that has its own unique values for its properties and the ability to perform its methods. Imagine a class as a house plan and the object as the actual house built from that plan. Each object is like a 'real' version with its own data, but all are based on the same design.

Here is an example shows you how you can create an object from a class in PHP:

$myCar = new Car();
$myCar->color = "Red";
$myCar->model = "Sedan";

echo $myCar->startEngine(); // outputs: Engine started!

In this example, $myCar is an object created from the Car class. It has its values for $color and $model, and it can use the startEngine method to start the engine. Each object acts as an independent entity, though all share the same structure from which they were created, the Car class.  

Creating and Using Multiple Objects in PHP OOP

One of the major benefits of using classes in PHP is that with one class, you can instantiate many objects. Each object is independent; thus, you can have different values for its properties without affecting other objects. Such reusability of a single blueprint of classes makes your code modular and flexible.

Here is an example of how one could instantiate multiple car objects:

$car1 = new Car();
$car1->color = "Red";
$car1->model = "SUV";

$car2 = new Car();
$car2->color = "Blue";
$car2->model = "Convertible";

echo "Car 1 is a " . $car1->color . " " . $car1->model; // Outputs: Car 1 is a Red SUV
echo "Car 2 is a " . $car2->color . " " . $car2->model; // Outputs: Car 2 is a Blue Convertible

Here, car1 and car2 are two different objects created from the class Car. Both have different values of $color and $model, but they share the same structure. With this, you can easily create and manage several instances, each having different data.  

Wrapping Up

OOP classes and objects in PHP enable you to write reusable, clean, and scalable code. Defining a class sets up a blueprint for creating multiple objects, each with unique properties and behaviors.

This approach makes your code modular, maintainable, and ready to scale as applications grow. Classes and objects will change how you approach coding. Instead of repetitive or one-use scripts, you will create clear components. This will make developing applications more understandable.

If you need more tutorials in PHP, click on this page.