SELECTION OF OPERATIONS

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ConsoleApplication1

{

    class Program

    {

        static void Main(string[] args)

        {

            Console.WriteLine("Enter the first number.");

            int a = Convert.ToInt16(Console.ReadLine());

            Console.WriteLine("Enter the second number.");

            int b = Convert.ToInt16(Console.ReadLine());

            Console.WriteLine("enter an operation to be performed (+,-,*,/)");

            string o = Console.ReadLine();

using if condition

            if (o.Trim() == "+")

            {

                Console.WriteLine(Convert.ToString(a+b));

            }

            else if (o.Trim() == "-")

            {

                Console.WriteLine(Convert.ToString(a - b));

            }

            else if (o.Trim() == "*")

            {

                Console.WriteLine(Convert.ToString(a * b));

            }

            else if (o.Trim() == "/")

            {

                Console.WriteLine(Convert.ToString(a / b));

            }

                  Console.WriteLine("end");

            Console.ReadLine();

        }

    }

}

Using switch condition

switch (o.Trim())

            {

                case "+":

                    Console.WriteLine(Convert.ToString(a + b));

                    break;

                case "-":

                    Console.WriteLine(Convert.ToString(a- b));

                    break;

                case "*":

                    Console.WriteLine(Convert.ToString(a * b));

                    break;

                case "/":

                    Console.WriteLine(Convert.ToString(a / b));

                    break;

       }

                  Console.WriteLine("end");

            Console.ReadLine();