string reverse - benchmark testing

stringReverse_benchmark1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace stringPerformance
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Diagnostics;

    namespace ConsoleApplication4
    {
        class Program
        {
            delegate string StringDelegate(string s);

            static void Benchmark(string description, StringDelegate d, int times, string text)
            {
                Stopwatch sw = new Stopwatch();
                sw.Start();
                for (int j = 0; j < times; j++)
                {
                    d(text);
                }
                sw.Stop();
                Console.WriteLine("{0} Ticks {1} : called {2} times.", sw.ElapsedTicks, description, times);
            }

            public static string ReverseXor(string s)
            {
                char[] charArray = s.ToCharArray();
                int len = s.Length - 1;

                for (int i = 0; i < len; i++, len--)
                {
                    charArray[i] ^= charArray[len];
                    charArray[len] ^= charArray[i];
                    charArray[i] ^= charArray[len];
                }

                return new string(charArray);
            }

            public static string ReverseSB(string text)
            {
                StringBuilder builder = new StringBuilder(text.Length);
                for (int i = text.Length - 1; i >= 0; i--)
                {
                    builder.Append(text[i]);
                }
                return builder.ToString();
            }

            public static string ReverseArray(string text)
            {
                char[] array = text.ToCharArray();
                Array.Reverse(array);
                return (new string(array));
            }

            public static string StringOfLength(int length)
            {
                Random random = new Random();
                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < length; i++)
                {
                    sb.Append(Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65))));
                }
                return sb.ToString();
            }

            static void Main(string[] args)
            {

                int[] lengths = new int[] { 1, 10, 15, 25, 50, 75, 100, 1000, 100000 };

                foreach (int l in lengths)
                {
                    int iterations = 10000;
                    string text = StringOfLength(l);
                    Benchmark(String.Format("String Builder (Length: {0})", l), ReverseSB, iterations, text);
                    Benchmark(String.Format("Array.Reverse (Length: {0})", l), ReverseArray, iterations, text);
                    Benchmark(String.Format("Xor (Length: {0})", l), ReverseXor, iterations, text);

                    Console.WriteLine();
                }

                Console.Read();
            }
        }
    }
}