C# Abstraction

Abstraction in C# is an OOP concept that hides the implementation details and shows only the essential features to the user.
It helps to reduce complexity and focus on what an object does, not how it does it.

Abstraction in C# can be achieved using:

Abstract Classes
Interfaces

🔹 1. Abstract Classes

Cannot be instantiated directly
Can contain abstract methods (no body) and concrete methods (with body)
Derived classes must implement abstract methods

Example

abstract class Shape
{
public abstract double Area(); // abstract method

public void Display()
{
Console.WriteLine("This is a shape."); // concrete method
}
}

class Rectangle : Shape
{
private double length, width;

public Rectangle(double l, double w)
{
length = l;
width = w;
}

public override double Area()
{
return length * width;
}
}




Rectangle r = new Rectangle(5, 10);
r.Display();
Console.WriteLine("Area: " + r.Area());

abstract class Shape

{

public abstract double Area(); // abstract method

public void Display()

{

Console.WriteLine("This is a shape."); // concrete method

}

class Rectangle : Shape

{

private double length, width;

public Rectangle(double l, double w)

{

length = l;

width = w;

}

public override double Area()

{

return length * width;

}

Rectangle r = new Rectangle(5, 10);

r.Display();

Console.WriteLine("Area: " + r.Area());

🔹 2. Interfaces

Defines a contract: methods/properties without implementation
A class implements an interface and provides the implementation
Supports multiple inheritance

Example

interface IVehicle
{
void Start();
void Stop();
}

class Car : IVehicle
{
public void Start()
{
Console.WriteLine("Car started");
}

public void Stop()
{
Console.WriteLine("Car stopped");
}
}




Car c = new Car();
c.Start();
c.Stop();

interface IVehicle

{

void Start();

void Stop();

}

class Car : IVehicle

{

public void Start()

{

Console.WriteLine("Car started");

}

public void Stop()

{

Console.WriteLine("Car stopped");

}

Car c = new Car();

c.Start();

c.Stop();

🔹 Abstract Class vs Interface

Feature	Abstract Class	Interface
Instantiation	Cannot instantiate	Cannot instantiate
Methods	Abstract + Concrete	Only abstract (C# 8+ supports default implementations)
Fields	Allowed	Not allowed
Inheritance	Single	Multiple
Access Modifiers	Allowed	Public only (by default)

🔹 Advantages of Abstraction

✔ Reduces complexity
✔ Focus on what an object does, not how
✔ Enforces a contract for derived classes
✔ Helps in scalable and maintainable design

🔹 Common Mistakes

❌ Trying to instantiate an abstract class
❌ Not implementing all interface methods
❌ Using abstract methods without override in derived class

🔹 Summary

Abstraction hides implementation details
Achieved using abstract classes or interfaces
Forces derived classes to implement essential functionality
Simplifies code and improves design

C# Abstraction

C# Abstraction

🔹 1. Abstract Classes

Example

🔹 2. Interfaces

Example

🔹 Abstract Class vs Interface

🔹 Advantages of Abstraction

🔹 Common Mistakes

🔹 Summary

You may also like...

C# Tutorial

C# Classes

C# Abstraction

C# Abstraction

🔹 1. Abstract Classes

Example

🔹 2. Interfaces

Example

🔹 Abstract Class vs Interface

🔹 Advantages of Abstraction

🔹 Common Mistakes

🔹 Summary

You may also like...

C# Class Members

C# Multiple Interfaces

C# Files

C# Tutorial

C# Classes