using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace fciv
{
    class Program
    {
        static void Main(string[] args)
        {
            var files = Directory.GetFiles(@"C:\oracle\", "*.sql", SearchOption.AllDirectories).OrderBy(_ => _).ToList();
            var outputXmlName = "result.xml";
            File.Delete(outputXmlName);

            var sw = new Stopwatch();
            sw.Start();

            using( var outputXml = File.AppendText(outputXmlName) )
            {             
                foreach (var file in files)
                {
                    var s = CheckSum(file, 4096);
                    outputXml.WriteLine(s);               
                }
                outputXml.Flush();
            }

            sw.Stop();
            var ts = sw.Elapsed;
            Debug.WriteLine(ts); // 出力例：00:00:00.9984668

        }

        private static string CheckSum(string file, int bufferSize)
        {
            try
            { 
                using (var sm = new BufferedStream(File.OpenRead(file), bufferSize))
                {
                    using( var sha = MD5.Create() )
                    { 
                        var checksum = sha.ComputeHash(sm);
                        return BitConverter.ToString(checksum).Replace("-", String.Empty).ToLower();
                    }
                }
            }
            catch 
            {
                // ファイルアクセス拒否時等…
                return string.Empty;
            }
        }
    }
}