Reverse of a string

Write a program in c# (c sharp) to   accept a string from user and display the  reverse of a string .

using System;

namespace ReverseofString
{

   class Program
    {
    static void Main(string[] args)
    {
            string str1, str2 = "";
            int len, i;
            Console.WriteLine("Enter a String:");
            str1 = Console.ReadLine();
            len = str1.Length;
            for (i = len - 1; i >= 0; i--)
            {
                str2 = str2 + str1[i];
            }
            Console.WriteLine("Reverse of the entered string is:  " + str2);
            Console.ReadKey();
        }
    }
}

If anyone have any doubt about the program , please comment and you can also mail me on "ibsarmschauhan13@gmail.com" and "makansingh42@yahoo.com".