How to read two char at time in c#?

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



namespace ConsoleApplication4

{

    class Program

    {

        static void Main(string[] args)

        {

            string str = "dotnetfunda";

            string c1 = string.Empty;

            for (int i = 0; i <= str.Length - 1; i++)

            {

                c1 = c1+str[i];               

                if (c1.Length == 2)

                {

                    Console.WriteLine(c1);

                    Console.ReadLine();

                    c1 = string.Empty;

                }

                else if (c1.Length == 1)

                {

                    if (i == str.Length - 1)

                    {

                        Console.WriteLine(c1);

                        Console.ReadLine();

                    }

                }

            }

           

        }

    }

}