StringReverse.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace CSharpBasic
{
    class Program
    {
        public delegate string StringDelegate(string s);

        public static void benchmark(string description, StringDelegate d, int times, string s){
            Stopwatch sw = new Stopwatch();
            sw.Start();
            for (int i = 0; i < times; i++ )
            {
                d(s);
            }
            sw.Stop();
            Console.WriteLine("{0} ticks.  {1}(Length:{2}), runs {3} times.", sw.ElapsedTicks, description, s.Length, times);
        }

        public static string reverseByAPI(string input){
            if (string.IsNullOrEmpty(input)) return input;

            char[] inputArrary = input.ToCharArray();
            Array.Reverse(inputArrary);

            return new string(inputArrary);
        }

        public static string reverseByBitwise(string input){
            if (string.IsNullOrEmpty(input)) return input;

            int halfLength = input.Length >> 1;
            char[] inputArray = input.ToCharArray();
            for (int i = 0; i < halfLength; i++ )
            {
                inputArray[i] ^= inputArray[input.Length - i -1];
                inputArray[input.Length - i -1] ^= inputArray[i];
                inputArray[i] ^= inputArray[input.Length - i -1];
            }
            return new string(inputArray);
        }

        public static string reverseByArray(string input)
        {
            if (string.IsNullOrEmpty(input)) return input;

            int halfLength = input.Length >> 1;
            char[] inputArray = input.ToCharArray();
            char temp;
            for (int i = 0; i < halfLength; i++)
            {
                temp = inputArray[i];
                inputArray[i] = inputArray[input.Length - i - 1];
                inputArray[input.Length - i - 1] = temp;
            }
            return new string(inputArray);
        }

        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();
        }

        public static void TestIntegrity(string description, StringDelegate d, string s){
            Console.WriteLine("String to be reversed: \"{0}\"",s);
            Console.WriteLine("String       reversed: \"{0}\", {1}", d(s), description);
            Console.WriteLine("-------------");
        }

        static void Main(string[] args)
        {
            string[] strs = {"1234567890",
                       "123",
                       "日本語"
                            };
            foreach (string s in strs)
            {
                TestIntegrity("Reversed by API", reverseByAPI, s);
                TestIntegrity("Reversed by Array", reverseByArray, s);
            }

            int[] lengthArray = { 1, 10, 100, 1000, 5000, 10000, 50000};
            foreach (int length in lengthArray)
            {
                string s = StringOfLength(length);
                benchmark("ReverseByAPI", reverseByAPI, 10000, s);
                benchmark("ReverseByXor", reverseByArray, 10000, s);
                Console.WriteLine("===============");
            }
            Console.ReadLine();
        }
    }
}