using System;

using System.Linq;

using System.Text;

​

​

namespace SimpleCalculator

{

    public class CalculatorEngine

    {

        public double Calculator(string argOperation, double argFirstNum, double argSecondNum)

        {

            double result;

            switch(argOperation.ToLower())

            {

                case "add":

                case "+":

                    result = argFirstNum + argSecondNum;

                    break;

                case "subtract":

                case "-":

                    result = argFirstNum - argSecondNum;

                    break;

                case "multiply":

                case "*":

                    result = argFirstNum * argSecondNum;

                    break;

                case "divide":

                case "/":

                    result = argFirstNum / argSecondNum;

                    break;

                default:

                    throw new InvalidOperationException("Specified operation is not recognized");

            }

            return result;

        }

    }

}