using System;

class Calculator

    {

        private float number1;

        private float number2;

        public float Number1

        {

            get { return number1; }

            set { number1 = value;}

        }

        public float Number2

        {

            get { return number2; }

            set { number2 = value;}

        }

        public Calculator()

        {

            number1 = 0;

            number2 = 0;

        }

        public float Add()

        {

            return number1 + number2;

        }

        public float Subtract()

        {

            return number1 - number2;

        }

        public float Multiply()

        {

            return number1 * number2;

        }

        public float Divide()

        {

            if (number2 != 0)

            {

                return number1 / number2;

            }

            else 

            {

                return float.NaN;

            }

        }

        public float performOperation(string operation)

        {

            switch(operation)

            {

                case "+":

                    return Add();

                case "-":

                    return Subtract();

                case "*":

                    return Multiply();

                case "/":

                    return Divide();

                default:

                return 0;

            }

        }

​

    }

​

public class Program

{

    public static void Main()

    {

        Calculator calculator = new Calculator();

        bool keepRunning = true;

        while(keepRunning == true)

        {

            Console.Write("Enter first number: ");

            calculator.Number1 = Convert.ToSingle(Console.ReadLine());

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

            calculator.Number2 = Convert.ToSingle(Console.ReadLine());

            Console.Write("Choose an operation (+,-,*,/): ");

            string operation = Console.ReadLine();

            float result = calculator.performOperation(operation);

            Console.WriteLine(result);

            Console.Write("Do you want to perform another calculation (yes/no): ");

            string userResponse = Console.ReadLine();

            if(userResponse == "yes")

            {

                keepRunning = true;

            }

            else

            {

                keepRunning = false;

            }

        }

        Console.Write("Calculator closed.");

    }

}