using System;

using System.Web;

using System.IO;

using System.Text;

using System.Linq;              

using System;

using System.Collections.Generic;

using System.Globalization;

using System.Linq;

using System.Text;

using System.Text.RegularExpressions;

using System.Threading;

using System.Threading.Tasks;

​

public class Program

{

    public static void Main()

    {

        var input = "HellÒ Wörld ÍÊÒÚÀöß";

        var sw = new System.Diagnostics.Stopwatch();

        sw.Start();

        var output1 =ReplaceSpecialCharacters(input, string.Empty);

        sw.Stop();

        Console.WriteLine("SW:"+sw.Elapsed);

        Console.WriteLine(input);

        sw.Restart();

        var chars = input.Select(d => d).Distinct();

        foreach(var bla in chars)

        {

            input = input.Replace(bla, GetBase(bla));

        }

        Console.WriteLine("SW:"+sw.Elapsed);

        Console.WriteLine(input);

        Console.WriteLine(output1);

    }

    public static char GetBase(char input)

        {

            var ignore = "ÖöÄäÜü";

​

            if (ignore.Contains(input))

            {

                return input;

            }

​

            var result = input.ToString().Normalize(NormalizationForm.FormD);

​

            return result[0];

        }

     private const string regexStr = @"[^a-zA-Z0-9äöüÄÖÜß'\- _.]+";

        public static string ReplaceSpecialCharacters(string str, string replaceCharacter)

        {

            if (string.IsNullOrWhiteSpace(str))

                return str;

​

            return Regex.Replace(Regex.Replace(str, regexStr, NormalizedReplace, RegexOptions.Compiled), regexStr, replaceCharacter, RegexOptions.Compiled);

        }

​

        private static string NormalizedReplace(Match match)

        {

            var erg = RemoveAccents(match.Value);

​

            return erg;

        }

​

        private static string RemoveAccents(string input)

        {

            return new string(

                input

                .Normalize(System.Text.NormalizationForm.FormD)

                .ToCharArray()

                .Where(c => CharUnicodeInfo.GetUnicodeCategory(c) != UnicodeCategory.NonSpacingMark)

                .ToArray());

        }

    public class Car

    {

    }

    public enum MyEnum

    {

        None = 0,

        One = 1,

        Two = 2,

    }

}