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

namespace FilesCompare
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Please type the first file.");
            string firstFilePath = Console.ReadLine();

            Console.WriteLine("Please type the second file.");
            string secondFilePath = Console.ReadLine();

            bool isEqual = CompareFiles(firstFilePath, secondFilePath);
            Console.WriteLine(isEqual ? "equal" : " Not equal");

            Console.Read();
        }

        public static bool CompareFiles(string targetFile, string updatedFile)
        {
            FileInfo targetFileInfo = new FileInfo(targetFile);
            FileInfo updatedFileInfo = new FileInfo(updatedFile);

            if (targetFileInfo.Length != updatedFileInfo.Length)
            {
                return false;
            }

            using (FileStream targetStream = File.OpenRead(targetFile))
            {
                using (FileStream updatedStream = File.OpenRead(updatedFile))
                {
                    if (targetStream.Length != updatedStream.Length)
                    {
                        return false;
                    }

                    // Using a larger buffer than the default buffer of 4 * 1024 used by FileStream.ReadByte improves performance.
                    // The buffer size is based on user feedback. Based on performance results, a better buffer size may be determined.
                    byte[] targetBuffer = new byte[16 * 1024];
                    byte[] updatedBuffer = new byte[16 * 1024];
                    int targetReadLength;
                    int updatedReadLength;
                    do
                    {
                        targetReadLength = targetStream.Read(targetBuffer, 0, targetBuffer.Length);
                        updatedReadLength = updatedStream.Read(updatedBuffer, 0, updatedBuffer.Length);

                        if (targetReadLength != updatedReadLength)
                        {
                            return false;
                        }

                        for (int i = 0; i < targetReadLength; ++i)
                        {
                            if (targetBuffer[i] != updatedBuffer[i])
                            {
                                return false;
                            }
                        }

                    } while (0 < targetReadLength);
                }
            }

            return true;
        }

    }
}