using System;

​

public class addition

{

    public int addpgm(int a, int b)

    {

        int c = a + b;

        return (c);

    }

}

​

public class subtraction

{

    public int subpgm(int a, int b)

    {

        int c = a - b;

        return (c);

    }

}

​

public class multiplication

{

    public int mulpgm(int a, int b)

    {

        int c = a * b;

        return (c);

    }

}

​

public class division

{

    public int divpgm(int a, int b)

    {

        int c = a / b;

        return (c);

    }

}

​

public class SimpleCalculator

{

    public static void Main()

    {

        int num1, num2;

        string ch;

        addition addnum = new addition();

        subtraction subnum = new subtraction();

        multiplication mulnum = new multiplication();

        division divnum = new division();

        do

        {   

            Console.Write("1. Addition\n");

            Console.Write("2. Subtraction\n");

            Console.Write("3. Multiplication\n");

            Console.Write("4. Division\n\n");

            Console.Write("Enter the required computing choice : ");

            int choice = int.Parse(Console.ReadLine());

            Console.Write("\nEnter the first number : ");

            num1 = int.Parse(Console.ReadLine());

​

            Console.Write("Enter the second number : ");

            num2 = int.Parse(Console.ReadLine());

            switch(choice)

            {

                case 1: System.Console.WriteLine("\nThe sum of " + num1 + " and " + num2 + " is " + addnum.addpgm(num1, num2));     

                break;

                case 2: System.Console.WriteLine("\nThe difference between " + num1 + " and " + num2 + " is " + subnum.subpgm(num1, num2));     

                break;

                case 3: System.Console.WriteLine("\nThe product of " + num1 + " and " + num2 + " is " + mulnum.mulpgm(num1, num2));     

                break;

                case 4: 

                    if(num2 != 0)

                    {

                        System.Console.WriteLine("\nThe quotient formed from " + num1 + " and " + num2 + " is " + divnum.divpgm(num1, num2));

                    }

                    else

                    {

                        System.Console.WriteLine("\nDivision By Zero causes Run - Time Exception");

                    }

                break;

                default: System.Console.WriteLine("\nINVALID CHOICE");

                break;  

            }

            Console.Write("\nDo you wish to Continue (y/n) ?");

            Console.WriteLine();

            ch = Console.ReadLine();

        }while(ch=="y");

    }

}

​

​