How Are Classes in PHP Work?

PHP is a popular server-side scripting language used for web development. One of the key features of PHP is its support for object-oriented programming (OOP). Classes in PHP are an essential part of OOP and play a crucial role in organizing and structuring code.

Let’s explore how classes work in PHP and understand their significance.

Defining a Class

In PHP, a class is defined using the class keyword followed by the class name. The class name should be written in PascalCase, starting with an uppercase letter. For example, let’s define a class called Car:

class Car {
// Class properties and methods go here
}

Properties and Methods

A class consists of properties and methods. Properties are variables that hold data, while methods are functions that perform actions or provide functionality. They are defined within the class scope.

Let’s add some properties and methods to our Car class:

class Car {
// Properties
public $brand;
public $color;

// Methods
public function startEngine() {
    // Code to start the engine
}

public function drive() {
    // Code to drive the car
}


}

In the example above, we added two properties: brand and color, and two methods: startEngine() and drive(). The public keyword denotes that these members can be accessed from outside the class.

Creating an Object

Once a class is defined, we can create objects or instances of that class. An object is a specific occurrence of a class, which has its own set of properties and can invoke the defined methods.

Let’s create an object of the Car class:

$myCar = new Car();

The new keyword is used to create a new object of the class. Here, $myCar is an instance of the Car class.

Accessing Properties and Methods

Once we have an object, we can access its properties and methods using the object operator (->).

For example, let’s set the brand and color properties of $myCar:

$myCar->brand = 'Tesla';
$myCar->color = 'Red';

We can also invoke the methods of the object:

$myCar->startEngine();
$myCar->drive();

Visibility Modifiers

In PHP, properties and methods can have visibility modifiers that determine their accessibility from different parts of the code. The three visibility modifiers in PHP are:

public: Members declared as public are accessible from anywhere, both within and outside the class.
protected: Members declared as protected are accessible within the class and its subclasses.
private: Members declared as private are only accessible within the class itself.

By default, if no visibility modifier is specified, the member is considered public.

Inheritance

Inheritance is a powerful feature of OOP that allows classes to inherit properties and methods from another class. The class that is being inherited from is called the parent or base class, while the class that inherits is called the child or derived class.

Let’s say we have a class called SportsCar that extends the Car class:

class SportsCar extends Car {
// Additional properties and methods specific to SportsCar
}

The SportsCar class inherits all the properties and methods from the Car class. It can also define its own additional properties and methods.

Conclusion

In PHP, classes are fundamental to object-oriented programming. They allow you to define properties and methods, create objects, and organize your code in a structured manner. Understanding how classes work in PHP is crucial for building robust and maintainable web applications.