C# Abstract Class - c# - c# tutorial - c# net
What is abstract class in C# ?
- Abstract classes are the way to achieve abstraction in C#. Abstraction in C# is the process to hide the internal details and showing functionality only. Abstraction can be achieved by two ways:
- Abstract class
- Interface
- Abstract class and interface both can have abstract methods which are necessary for abstraction.
Abstract Class
Abstract Method
- A method which is declared abstract and has no body is called abstract method.
- It can be declared inside the abstract class only.
- Its implementation must be provided by derived classes. For example:
public abstract void draw();
Note: An abstract method in C# is internally a virtual method so it can be overridden by the derived class.
- You can't use static and virtual modifiers in abstract method declaration.
C# Abstract class
- In C#, abstract class is a class which is declared abstract. It can have abstract and non-abstract methods.
- It cannot be instantiated. Its implementation must be provided by derived classes. Here, derived class is forced to provide the implementation of all the abstract methods.
- Let's see an example of abstract class in C# which has one abstract method draw().
- Its implementation is provided by derived classes: Rectangle and Circle. Both classes have different implementation.
using System;
public abstract class Shape
{
public abstract void draw();
}
public class Rectangle : Shape
{
public override void draw()
{
Console.WriteLine("drawing rectangle...");
}
}
public class Circle : Shape
{
public override void draw()
{
Console.WriteLine("drawing circle...");
}
}
public class TestAbstract
{
public static void Main()
{
Shape s;
s = new Rectangle();
s.draw();
s = new Circle();
s.draw();
}
}
C# examples - Output :
drawing rectangle...
drawing circle...
Abstract vs interface in c# :
abstract vs interface csharp in c# Example