OOPS Concepts in PHP | Object Oriented Programming in PHP

Object-Oriented Programming (OOP) in PHP organizes code into classes and objects, enabling more structured, reusable, and maintainable code. Unlike procedural programming, OOP bundles data and functions together, making it easier to model real-world concepts.

For instance, a Product class could have properties like name and price, with methods like getPrice() to retrieve the product's price. This allows you to create multiple product objects, each with its own unique values, while keeping the code organized and reusable.

In this blog, we’ll explore key OOP concepts in PHP, such as classes, objects, inheritance, and polymorphism, providing you with the knowledge to write clean and efficient PHP code.

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Object Oriented Programming (OOP) in PHP: Popular OOP Concepts

Object-oriented programming in PHP helps developers build reusable and complex web applications. Object-oriented programming is a programming style that refers to the association of various components and revolves around the inheritance, polymorphism, encapsulation, and abstraction concepts.

OOP is programmed in such a way that the users can focus on the object while developing the program and code, but not the procedure. OOP also focuses on drawing programming close to real life.

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Here are five key features of Object-Oriented Programming (OOP) in PHP:

• Encapsulation: Encapsulation allows you to bundle data (properties) and methods (functions) that operate on the data within a class.
• Inheritance: Inheritance enables one class (child class) to inherit properties and methods from another class (parent class).
• Polymorphism: Polymorphism allows objects of different classes to be treated as objects of a common superclass. 
• Abstraction: Abstraction involves creating abstract classes or interfaces, which define methods that must be implemented by subclasses.
• Access Modifiers: PHP provides access modifiers like public, protected, and private to control the visibility of class properties and methods.

These features of OOP in PHP help create modular, reusable, and maintainable code, making it easier to scale and manage larger applications.

Also Read: What are the Advantages of Object-Oriented Programming?

Key Terms Related to Object-Oriented Programming (OOP)

Understanding key terms related to Object-Oriented Programming (OOP) is crucial because they form the foundation of how OOP structures and organizes code. Grasping concepts like classes, objects, inheritance, and abstraction enables developers to design flexible, reusable, and maintainable software. 

Without a clear understanding of these terms, it becomes challenging to write efficient code, collaborate effectively, or leverage the full power of OOP principles in languages like PHP or Java. Mastery of this vocabulary ensures smoother learning curves and better communication within development teams.

Knowledge of these terms forms the foundation for building modular, reusable, and organized code in PHP:

• Object: An instance of a class representing a specific entity with its own values for the properties defined by the class.
• Member Variable (Attribute): Variables defined within a class that hold data specific to an object.
• Member Function (Method): Functions defined within a class that operate on the object’s data and define its behaviors.
• Parent Class (Super Class/Base Class): A class whose properties and methods are inherited by another class.
• Child Class (Subclass/Derived Class): A class that inherits from a parent class and can add or modify functionalities.

Also Read: Understanding Encapsulation in OOPS with Examples

Now that you have a good understanding of main terms related to OOP, let’s look at the top OOP concepts you need to be familiar with.

Core OOP Concepts in PHP with Examples

Object-oriented programming in PHP provides a structured approach to writing code that is modular, scalable, and easier to maintain. By focusing on creating reusable components and clear abstractions, PHP developers can build applications that are both flexible and robust, streamlining development and improving code quality across projects.

These are the fundamental concepts that form the backbone of OOP in PHP:

1. Classes and Objects

• A class is a programmer-defined data type comprising variables and methods.
• An object is a specific instance of a class, having unique values but sharing the structure and behavior defined by the class.
• Example: You can define a Car class and create multiple Car objects like car1, car2 with different attributes.

2. Interfaces

• An interface defines a contract by specifying methods that implementing classes must provide.
• Interfaces contain only public methods and are declared with the interface keyword.
• Classes can implement multiple interfaces to ensure consistent behavior.

3. Abstraction

• Abstraction hides complex implementation details and exposes only the necessary parts to the user.
• It helps focus on “what” an object does rather than “how” it does it.
• Abstract classes and interfaces are typical ways to achieve abstraction.

4. Constructors and Destructors

• A constructor (__construct) is a special method automatically called when an object is instantiated, typically used to initialize properties.
• A destructor (__destruct) is called when an object is destroyed or goes out of scope, used for cleanup tasks.

5. Overloading

• Overloading allows methods or operators to have multiple behaviors based on different argument types or numbers.
• In PHP, method overloading can be simulated using magic methods like __call.

Also Read: A Complete Guide on OOPs Concepts in Python

Major Principles of OOP in PHP

Mastering OOP in PHP requires understanding its core principles, which enable secure, reusable, and flexible code. These concepts help organize data and behavior, establish class hierarchies, and allow methods to adapt dynamically, making your PHP applications clean, efficient, and scalable.

Here are the key principles OOP in PHP:

1. Encapsulation

• Combines data (properties) and code (methods) into a single unit or class.
• Controls access to the internal state using access modifiers (public, protected, private).
• Protects the object’s data and reduces complexity by hiding implementation details.

2. Inheritance

• Establishes a parent-child relationship between classes where the child inherits properties and methods of the parent.
• Promotes code reuse and allows extending or modifying base class behavior.
• Can be single-level or multi-level inheritance.

3. Polymorphism

• Allows methods to behave differently based on the object calling them, supporting method overriding and overloading.
• Enables a single interface to represent different underlying forms (data types).
• Facilitates flexibility and extensibility in code design.

Also Read: Explore Object-Oriented Programming in Python 2025

Now that you understand the core OOP concepts in PHP, let’s move to the key principles of OOP.

Creating Objects in PHP

First and foremost, in PHP, classes are created where users can create several objects in the same class by their choice. Each object is created with the help of a new keyword. When a class is created, the developers can create as many numbers of objects as they want for the same class.

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1. Calling Member Function

When the object is created, developers can access the method functions and variables of the class using the operator ‘->’. One member function is able to process the member variables of related objects only. Let us take an example that shows how to set the price and title for any three books by calling the member functions:

$physics->setTitle( “Physics for High School” );

$chemistry->setTitle( “Advanced Chemistry” );

$maths->setTitle( “Algebra” );

$physics->setPrice( 10 );

$chemistry->setPrice( 15 );

$maths->setPrice( 7 );

To get the value set you can call another member functions:

$physics->getTitle();

$chemistry->getTitle();

$maths->getTitle();

$physics->getPrice();

$chemistry->getPrice();

$maths->getPrice();

This will produce the following result:

Physics for High School

Advanced Chemistry

Algebra

10

15

7

2. Creating Abstract Class

An abstract class in PHP serves as a blueprint for other classes and cannot be instantiated directly. It allows you to define abstract methods that child classes must implement, enforcing a consistent interface while providing shared functionality.

<?php

abstract class DBCommonMethods

{

    private $host;

    private $db;

    private $uid;

    private $password;

    public function __construct($host, $db, $uid, $password)

    {

        $this->host = $host;

        $this->db = $db;

        $this->uid = $uid;

        $this->password = $password;

    }

}

?>

Here,

• “Abstract class” refers to the class that cannot be used directly for creating an object.
• “$host,$db …” are the class variables common in various implementations

3. Creating interface

Let us now create an interface containing standard methods to implement different database variables:

<?php

interface DBInterface

{

    public function db_connect();

    public function insert($data);

    public function read($where);

    public function update($where);

    public function delete($where);

}

?>

Here,

• “Interface” is a keyword for creating the interfaces
• “Public function” is a standard method to implement

4. Creating Concrete Class

Let us create a concrete class that can extend DBCommon Methods classes and interfaces:

<?php class MySQLDriver extends 

DBCommonMethods implements DBInterface { public function __construct($host, $db, $uid, $password) 

{ 

parent::__construct($host, $db, $uid, $password); } 

public function db_connect() { //connect code goes here } 

public function delete($where) { //delete code goes here } 

public function insert($data) { //insert code goes here } 

public function read($where) { //read code goes here } 

public function update($where) { //update code goes here } 

} ?>

5. Function overriding

Function in child classes override within the same name as the parent class. In a child class, the developer can modify the function definition inherited from the parent class.

function getPrice() {

   echo $this->price . “<br/>”;

   return $this->price;

} 

function getTitle(){

   echo $this->title . “<br/>”;

   return $this->title;

}

6. Visibility

Each method and property in PHP has its visibility that is declared by keywords like private, public, and protected which are explained below: 

• Public- It allows any user from outside to access the method and property.
• Private- It does not give access to any user except itself.
• Protected- It only allows children classes and itself to access the method and property.

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Also Read: Master Polymorphism in OOP: Key Insights on Types & Examples

Now that you know how to create objects in PHP, let’s explore some of the more advanced OOPs concepts in PHP.

Advanced OOPs Concepts In PHP

So far, we have learned some of the most popular OOPs concepts in PHP with examples. If you are looking for something more on the advanced level, don’t worry we have got you covered. The mentioned below list highlights some of the more advanced OOPs concepts in PHP.

• Protected Scope- As the name suggests itself, protected scopes are private, and can be accessed only through cloud accesses. It is very similar to private scopes, the only difference being private scope is accessible only to the exact class that has the property.
• Accessors And Mutators- Accessors, also sometimes referred to as getters, are functions that return the value of a class property. Mutators, on the other hand, are functions that change the value of a class property. Both these functions are especially useful when you are dealing with a large system or a complicated class. 
• The __get Method- There are certain methods that exist to make your class smarter. They are present in every class, but PHP handles them by default. One such method is the __get method. It is a simple accessor function that you can use when you want to get a property that does not exist. 
• The __set method- Completely opposite to the __get method, the __set method is used when your code tries to set a property that does not exist.
• The __construct method -Last but not least, yet another popular OOps concept in PHP is the __construct method. You can use this method when you want to create a new instance of a class or some really elegant code. Most of the time, this method is used to automatically run some extra code while the instance is created. 

Also Read: OOP vs POP: Difference Between POP and OOP

Next, let’s see how upGrad can help you improve your knowledge of OOPs Concepts in PHP.

Upskill with upGrad and Learn OOP

Mastering Object-Oriented Programming (OOP) in PHP is essential for writing clean, scalable, and maintainable code. Choosing the right learning path can speed up your progress and deepen your understanding of key concepts like classes, inheritance, and polymorphism. 

upGrad offers expertly designed PHP courses tailored to your skill level and career goals. With millions of learners and strong industry connections, upGrad provides the support and resources you need to excel in PHP development, from fundamentals to advanced OOP techniques. Start your journey with upGrad and transform your PHP coding skills today.

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References:

https://www.zend.com/blog/object-oriented-programming-php