C# Tutorial 7.4: Abstraction

 Abstraction is an important concept in object-oriented programming (OOP) and is one of the key principles of OOP. In C#, abstraction is achieved through abstract classes and interfaces. This tutorial will guide you through the basics of abstraction in C#.

Abstraction in C#

1. Abstract Classes:

An abstract class is a class that cannot be instantiated and is typically used as a base class for other classes. It may contain abstract and non-abstract (concrete) methods. Abstract methods have no implementation in the abstract class and must be implemented by derived classes.

// Example of an abstract class
abstract class Shape
{
    public abstract void Draw(); // Abstract method with no implementation
    public void Display()
    {
        Console.WriteLine("Displaying shape");
    }
}
// Derived class implementing the abstract method
class Circle : Shape
{
    public override void Draw()
    {
        Console.WriteLine("Drawing a circle");
    }
}

2. Interfaces:

An interface is a contract that defines a set of methods and properties that a class must implement. Unlike abstract classes, interfaces can be implemented by multiple classes, providing a way to achieve multiple inheritances in C#.

// Example of an interface
interface IDrawable
{
    void Draw();
}
// Class implementing the interface
class Square : IDrawable
{
    public void Draw()
    {
        Console.WriteLine("Drawing a square");
    }
}

3. Using Abstraction in Code:

Now, let's use the abstract class and interface in a program:

class Program
{
    static void Main()
    {
        // Using abstract class
        Shape circle = new Circle();
        circle.Draw();    // Calls the overridden method in Circle
        circle.Display(); // Calls the method in the abstract class
        // Using interface
        IDrawable square = new Square();
        square.Draw();    // Calls the method in Square
    }
}

Summary:

• Abstraction helps in hiding the complex implementation details and exposing only the necessary functionalities.
• Abstract classes and interfaces provide a way to achieve abstraction in C#.
• Abstract classes can have a mix of abstract and concrete methods, while interfaces only contain method and property declarations.
• Abstract classes are used for common functionality among derived classes, and interfaces define a contract that multiple classes can implement.