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What is the use of interface in C# ?

  • Interface in C# is a blueprint of a class. It is like abstract class because all the methods which are declared inside the interface are abstract methods.
  • It cannot have method body and cannot be instantiated.
  • It is used to achieve multiple inheritance which can't be achieved by class.
  • It is used to achieve fully abstraction because it cannot have method body.
  • Its implementation must be provided by class or struct.
  • The class or struct which implements the interface, must provide the implementation of all the methods declared inside the interface.
Interface

Interface

C# interface example

  • Let's see the example of interface in C# which has draw() method. Its implementation is provided by two classes: Rectangle and Circle.
using System;  
public interface Drawable  
{  
void draw();  
}  
public class Rectangle : Drawable  
{  
public void draw()  
{  
Console.WriteLine("drawing rectangle...");  
}  
}  
public class Circle : Drawable  
{

public void draw()  
{  
Console.WriteLine("drawing circle...");  
}  
}  
public class TestInterface  
{  
public static void Main()  
{  
Drawable d;  
d = new Rectangle();  
d.draw();  
d = new Circle();  
d.draw();  
}  
}  
click below button to copy the code. By - c# tutorial - team

C# examples - Output :

drawing rectangle...
drawing circle…

Note: Interface methods are public and abstract by default. You cannot explicitly use public and abstract keywords for an interface method.

learn c# tutorials - Abstract vs Interface Csharp in c#

learn c# tutorial - Abstract vs Interface Csharp in c# Example

using System;  
public interface Drawable  
{  
public abstract void draw();//Compile Time Error  
}  
click below button to copy the code. By - c# tutorial - team


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