How to convert string to an array of characters in C#?

using System;

using System.IO;

namespace FileOperationsSample

{

    class Program

    {

        public static void Main(String[] args)

        {

            String str = "I am string";

            // We need to create an array with size of string length

            char[] b = new char[str.Length];

            // Load string in a StringReader

            StringReader sr = new StringReader(str);

            sr.Read(b, 0, 11);

            Console.WriteLine(b);

            sr.Close();

            Console.ReadLine();

        }

    }

}