Interfaces In C# Programming – A Complete Guide

Interfaces in C# programming is a very crucial concept and quite confusing for a lot of developers to understand and implement. So I have created C# interfaces article to make sure, even a basic developer also can understand.

After going through this article, you will get the complete knowledge of interfaces like

  • What is an interface?
  • When to use interfaces?
  • Where to use interface?

C# Interfaces | Interfaces In C#

Let’s understand what c# interfaces are?.

Interfaces are declared using interface keyword. An interface is like a contract that all derived classes/interfaces should follow.

In other words, it’s like rules defined in the interface and these interface rules has to be followed by derived class or interfaces.¬†So remember we are defining rules in interfaces and forcing them to follow in next subclasses.

Example: How to declare and implement interfaces in c#?

If you look at the above code, we have declared “IInput” interface with two methods (rules).

  • getkeyBoard()
  • getMouse()

In subsequent classes of Computer and Laptop, I am implementing the same rules defined in IInput Interface. I hope now you understood how to create rules and implement methods (rules) using interfaces in c#.

Features about Interfaces in c#

  • Interfaces are declared using interface keyword.
  • All methods in interfaces are by default public and we can’t change them.
  • An Interface contains methods with no implementations.
  • Interfaces may contain properties, methods, events, and indexers.
  • Any Interfaces cannot be Instantiated directly.