using System;

public class Program

{

    public static void Main()

    {

        var calculator = new AreaCalculator();

        //// call the first compute method

        var firstResult = calculator.Compute(3,2);

        //// call the second compute method 

        var secondResult = calculator.Compute(3,2,2);

        var addition = new Addition();

        var sum = addition.Compute(4,2);

        Console.WriteLine(sum);

        addition.Display("something");

        var subtraction = new Subtraction();

        subtraction.Display("something else");

        //// because of polymorphism having the same method name was allowed since it has a different set of parameters

        Console.WriteLine(firstResult);

        Console.WriteLine(secondResult);

    }

}

​

//// Encapsulation sample

public class Person {

    public string Name;

    public int Age;

    public int getAge () {

        return this.Age;

    }

    public void setAge (int age) {

        this.Age = age;

    }

    public string getName () {

        return this.Name;

    }

    public void setName (string name) {

        this.Name = name;

    }

}

​

//// Polymorphism sample (overloading)

public class AreaCalculator {

    public int Compute(int length, int width) {

        return length * width;

    }

    public int Compute(int length, int width, int height) {

        return length * width * height;

    }

}

​

public abstract class Calculator {

    //// this is the method that we will override

    public abstract int Compute(int firstNumber, int secondNumber);

    public virtual void Display(string text) {

        Console.WriteLine("default"+text);

    }

​

}

​

​

public class Addition : Calculator {

    //// overrides the compute method to perform addition

    public override int Compute(int firstNumber, int secondNumber) {

        return firstNumber + secondNumber;

    }

    public override void Display(string text){

        Console.WriteLine("from addition"+text);

    }

}

​

public class Subtraction : Calculator {

    //// overrides the compute method to perform subtraction

    public override int Compute(int firstNumber, int secondNumber) {

        return firstNumber - secondNumber;

    }

}