C# - Inheritance

Inheritance in C#

Inheritance is a fundamental concept in Object-Oriented Programming (OOP) that allows one class to inherit the fields and methods of another class. The class that is inherited from is called the base class or superclass, and the class that inherits is called the derived class or subclass. Inheritance promotes code reuse and establishes a relationship between classes.

Here's a detailed example to illustrate inheritance in C#:

Base Class

Let's start with a simple base class called Animal that has some common properties and methods.

public class Animal
{
    // Properties
    public string Name { get; set; }
    public int Age { get; set; }

    // Constructor
    public Animal(string name, int age)
    {
        Name = name;
        Age = age;
    }

    // Method
    public void Eat()
    {
        Console.WriteLine($"{Name} is eating.");
    }

    // Virtual method to be overridden by derived classes
    public virtual void MakeSound()
    {
        Console.WriteLine($"{Name} is making a sound.");
    }
}

Derived Class

Now, let's create a derived class called Dog that inherits from the Animal class. The Dog class will have its own additional properties and methods, and it will override the MakeSound method from the Animal class.

public class Dog : Animal
{
    // Additional property
    public string Breed { get; set; }

    // Constructor that calls the base class constructor
    public Dog(string name, int age, string breed) : base(name, age)
    {
        Breed = breed;
    }

    // New method specific to Dog
    public void Bark()
    {
        Console.WriteLine($"{Name} is barking.");
    }

    // Override the MakeSound method
    public override void MakeSound()
    {
        Console.WriteLine($"{Name} is barking.");
    }
}

Another Derived Class

Let's create another derived class called Cat that also inherits from the Animal class.

public class Cat : Animal
{
    // Additional property
    public string Color { get; set; }

    // Constructor that calls the base class constructor
    public Cat(string name, int age, string color) : base(name, age)
    {
        Color = color;
    }

    // New method specific to Cat
    public void Meow()
    {
        Console.WriteLine($"{Name} is meowing.");
    }

    // Override the MakeSound method
    public override void MakeSound()
    {
        Console.WriteLine($"{Name} is meowing.");
    }
}

Using the Classes

Here's how you can use these classes to create objects and call their methods.

public class Program
{
    public static void Main(string[] args)
    {
        // Create a Dog object
        Dog myDog = new Dog("Buddy", 3, "Golden Retriever");
        myDog.Eat();             // Inherited method
        myDog.Bark();            // Dog-specific method
        myDog.MakeSound();       // Overridden method

        // Create a Cat object
        Cat myCat = new Cat("Whiskers", 2, "Black");
        myCat.Eat();             // Inherited method
        myCat.Meow();            // Cat-specific method
        myCat.MakeSound();       // Overridden method
    }
}

Output

Buddy is eating.
Buddy is barking.
Buddy is barking.
Whiskers is eating.
Whiskers is meowing.
Whiskers is meowing.

Explanation

Base Class (Animal):

• Contains properties Name and Age.
• Has a constructor to initialize these properties.
• Contains a method Eat that is inherited by all derived classes.
• Contains a virtual method MakeSound that can be overridden by derived classes.
  

Derived Class (Dog):

• Inherits from Animal and adds an additional property Breed.
• Has a constructor that calls the base class constructor using base.
• Contains a new method Bark.
• Overrides the MakeSound method to provide a specific implementation for Dog.

Another Derived Class (Cat):

• Inherits from Animal and adds an additional property Color.
• Has a constructor that calls the base class constructor using base.
• Contains a new method Meow.
• Overrides the MakeSound method to provide a specific implementation for Cat.