What is an Interface in PHP? | Intellipaat

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What is Interface in PHP
Updated on 07th Aug, 23 6.6 K Views

PHP is a widely-used open-source scripting language that is particularly suited for web development. It is a server-side scripting language that is used to create dynamic web pages that can interact with databases and other web services. PHP is fast, reliable, and easy to use, making it a popular choice for web developers around the world. One of the most powerful features of PHP is the ability to define interfaces, which allows for greater flexibility and maintainability in your code. In the blog, we will find more of it.

Table of Contents:

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Introduction to PHP Interface

A PHP interface refers to the blueprint of a class, which sets an agreement that a class has to follow. The working of the PHP interface is similar to the working class for its objects. The interface is a feature of OOPs that allows you to create functions without defining their actual implementation. 

Below mentioned are the pointers which will help you to understand the PHP interface in-depth – 

  • The concept of interface is a widely used concept in the domain of computer programming.
  • Quick switching between the implementations is possible due to the PHP interface.
  • The class which implements the concept of interface is known as the concrete class.
  • It helps the developers to serve the objects in a more abstract manner.
  • In PHP interfaces are defined in two ways. The first one is publicly visible constant and the second one is publicly visible methods.
  • PHP interfaces should be named according to the naming nomenclature. The initials should be capitalized. 

For example, interface Intellipaat; or interface IntellipaatIndia;

  • PHP interface is easy to implement. Its syntax is
Interface InterfaceName

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PHP Interface Example

Below mentioned is an example of a PHP interface that shows the basic implementation of the PHP interface. In the below example, we have declared and defined two PHP interfaces.

<!--PHP Interface code snippet-->
interface PhpInterface{
    public function phpmethod1();
    public function phpmethod2();

class MyClass implements PhpInterface{
    public function phpmethod1(){
        echo "First Method is Displayed" . "\n";
    public function phpmethod2(){
        echo "Second Method is Displayed". "\n";

$obj = new MyClass;

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Abstract Class vs Interface Class

abstract class vs interface class

Abstract class and Interface class are usually misunderstood by learners. Below mentioned are the differentiating factors between the Abstract class and the Interface class. 

FactorAbstract ClassInterface Class
Type of abstractionPartial abstractionFull abstraction
Keyword usedExtend keyword is used.Implement keyword is used.
Type of specifierIt uses any type of access specifier.It uses public access specifier.
InheritanceMultiple inheritance is not possible.Multiple inheritance is possible.
Static membersA complete member can be static.No member can be static.
ContainersSupport containers.Does not support containers.

Features of PHP Interface

features of php interface

Due to the introduction of the PHP interface, developers were able to edit without amending the underlying code. Similarly, there are many other features that make the PHP interface an ideal choice.

The following are the features of the PHP interface.

  • Abstraction: Abstraction is a fundamental concept in object-oriented programming (OOP). An interface provides a way to define a set of methods that a class must implement without specifying how those methods are implemented. This allows for better separation of concerns, making it easier to modify and maintain code.
  • Encapsulation: Encapsulation is another essential OOP concept that interfaces support. By defining a set of methods that a class must implement, an interface provides a clear contract between different parts of a program. This makes it easier to understand how different components interact with each other.
  • Polymorphism: Polymorphism is the ability of an object to take on many forms. With interfaces, you can define a set of methods that can be implemented by different classes. This allows you to write code that is more flexible and adaptable, making it easier to add new features or modify existing ones.
  • Multiple Inheritance: Multiple inheritance is a feature of OOP that allows a class to inherit from multiple parent classes. In PHP, a class can implement multiple interfaces, which provides a way to achieve the benefits of multiple inheritances without the complications and potential problems that can arise.
  • Type Hinting: Type hinting is a feature in PHP that allows you to specify the expected data type for a function argument or return value. When you use an interface as a type hint, you are indicating that the argument or return value must be an instance of a class that implements that interface. This helps to ensure that the code is more reliable and less prone to errors.
  • Dependency Injection: Dependency injection is a design pattern that allows you to inject dependencies into a class, rather than having the class create them itself. By using interfaces to define dependencies, you can write code that is more modular and easier to test. This can lead to more robust and maintainable code.

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Career Transition


PHP provides a powerful tool for creating modular and extensible code. By defining a set of methods that a class must implement, interfaces enable developers to establish a contract between different components of an application, ensuring that they can work together seamlessly. While interfaces can be a bit challenging to understand at first, taking the time to learn about them can pay off in terms of cleaner, more maintainable code. By using interfaces, you can design your code in a way that makes it easier to test, refactor, and extend in the future.

As with any programming concept, there is always more to learn about interfaces and how to use them effectively. However, by understanding the basics of what interfaces are and how they work in PHP, you can take your coding skills to the next level and create more robust and flexible applications.

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