---
title: "What is the purpose of an interface in programming, and how does it differ from a class?"  
description: "What is the purpose of an interface in programming, and how does it differ from a class?"  
author: "Steilla Mitchel"  
published: 2023-06-21  
updated: 2023-06-24  
canonical: https://www.mindstick.com/forum/158823/what-is-the-purpose-of-an-interface-in-programming-and-how-does-it-differ-from-a-class  
category: "c#"  
tags: ["interface", "programming language"]  
reading_time: 2 minutes  

---

# What is the purpose of an interface in programming, and how does it differ from a class?

What is the [purpose of an interface](https://www.mindstick.com/forum/158817/what-is-the-purpose-of-an-interface-in-oop) in [programming](https://www.mindstick.com/articles/12214/web-development-company-in-india-laid-on-the-foundation-of-concrete-java-programming), and how does it differ from a [class](https://www.mindstick.com/blog/165/generic-class-in-c-sharp)?

## Replies

### Reply by Aryan Kumar

An [interface](https://www.mindstick.com/articles/12101/interfaces-in-java-extending-interfaces) in programming is a contract that specifies the behavior of a class. It defines the methods that a class must implement, but it does not define how the methods are implemented. Interfaces are useful for decoupling different parts of a program and for allowing different implementations of the same interface.

Here are some of the purposes of an interface in programming:

- **Decoupling different parts of a program:** Interfaces allow different parts of a program to interact with each other without knowing about each other's implementation details. This can make the program more modular and easier to maintain.
- **Allowing different implementations of the same interface:** Interfaces allow different implementations of the same interface. This can be useful for providing different implementations of the same interface for different platforms or for different purposes.

Here are some of the differences between an interface and a class:

- An interface defines the methods that a class must implement, but it does not define how the methods are implemented. A class defines both the methods that the class implements and how the methods are implemented.
- An interface cannot be instantiated, but a class can be instantiated.
- An interface can be implemented by multiple classes, but a class can only implement one interface.

Here is an example of an interface in Rust:

Rust

```plaintext
pub trait Foo {
  fn foo(&self);
}
```

This interface defines a single method called `foo()`. Any class that implements the `Foo` interface must implement the `foo()` method.

Here is an example of a class that implements the `Foo` interface:

Rust

```plaintext
struct Bar {
  // ...
}

impl Foo for Bar {
  fn foo(&self) {
    // ...
  }
}
```

This class implements the `Foo` interface by defining the `foo()` method.

As you can see, the interface defines the behavior of the class, but it does not define how the behavior is implemented. This allows different classes to implement the same interface in different ways.


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Original Source: https://www.mindstick.com/forum/158823/what-is-the-purpose-of-an-interface-in-programming-and-how-does-it-differ-from-a-class

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