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 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();  
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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();  
}  
}  
click below button to copy the code. By - c# tutorial - team

C# examples - Output :

drawing rectangle...
drawing circle...
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Abstract vs interface in c# :

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