Remove accents from a text file

Question

I have issues with removing accents from a text file program replaces characters with diacritics to ? Here is my code:

        private void button3_Click(object sender, EventArgs e)
        {

           if (radioButton3.Checked)
            {
                byte[] tmp;
                tmp = System.Text.Encoding.GetEncoding("ISO-8859-1").GetBytes(richTextBox1.Text);
                richTextBox2.Text = System.Text.Encoding.UTF8.GetString(tmp);


            }

        }

Answer 1

Taken from here: https://stackoverflow.com/a/249126/3047078

static string RemoveDiacritics(string text)
{
  var normalizedString = text.Normalize(NormalizationForm.FormD);
  var stringBuilder = new StringBuilder();

  foreach (var c in normalizedString)
  {
    var unicodeCategory = CharUnicodeInfo.GetUnicodeCategory(c);
    if (unicodeCategory != UnicodeCategory.NonSpacingMark)
    {
      stringBuilder.Append(c);
    }
  }

  return stringBuilder.ToString().Normalize(NormalizationForm.FormC);
}

usage:

string result = RemoveDiacritics("včľťšľžšžščýščýťčáčáčťáčáťýčťž");

results in vcltslzszscyscytcacactacatyctz

Answer 2

richTextBox1.Text = "včľťšľžšžščýščýťčáčáčťáčáťýčťž";            

string text1 = richTextBox1.Text.Normalize(NormalizationForm.FormD);

string pattern = @"\p{M}";
string text2 = Regex.Replace(text1, pattern, "�");

richTextBox2.Text = text2;

First normalize the string.
Then with a regular expression replace all diacritics. Pattern \p{M} is Unicode Category - All diacritic marks.