Find duplicate files within directory structure.

a.txt

testing

b.txt

123

c.txt

testing

FindDupes.cs

//
//  Main.cs
//
//  Author:
//       pjensen <jensen.petej@gmail.com>

using System;
using System.Security.Cryptography;
using System.IO;
using System.Collections.Generic;
using System.Text;

namespace Sample
{
    class Main
    {
        static Dictionary<string,List<string>> fileHashes = new Dictionary<string, List<string>>();

        public static void Main(string[] args)
        {
            if (args.Length == 0)
            {
                Console.WriteLine("no input args");
                return;
            }
            else if (args.Length == 1)
            {
                DFS(args [0], delegate(string file)
                {
                    var tmpFileHashBytes = HashAlgorithm.Create("SHA256").ComputeHash(File.Open(file, FileMode.Open));
                    var tmpFileHashStr = ASCIIEncoding.UTF8.GetString(tmpFileHashBytes);

                    if (fileHashes.ContainsKey(tmpFileHashStr))
                    {
                        fileHashes [tmpFileHashStr].Add(file);
                    }
                    else
                    {
                        fileHashes.Add(tmpFileHashStr, new List<string> { file });
                    }
                }
                );
            }

            ShowDuplicates();

            Console.ReadKey();
        }

        static void ShowDuplicates()
        {
            foreach (var k in fileHashes.Keys)
            {
                if (fileHashes [k].Count > 1)
                {
                    foreach (var v in fileHashes [k])
                    {
                        Console.WriteLine(v);
                    }
                }
            }
        }

        static void DFS(string aPath, Action<string> action)
        {
            foreach (string s in Directory.EnumerateDirectories(aPath))
            {
                DFS(s, action);
            }

            foreach (string s in Directory.EnumerateFiles(aPath))
            {
                action(s);
            }
        }
    }
}

/users/pjensen/ttt/a.txt
/users/pjensen/ttt/c.txt