How do i replace accents (german) in .NET

Question

I need to replace accents in the string to their english equivalents

for example

ä = ae

ö = oe

Ö = Oe

ü = ue

I know to strip of them from string but i was unaware about replacement.

Please let me know if you have some suggestions. I am coding in C#

Take a look at the answers mentioning "RemoveDiacritics" here: https://stackoverflow.com/questions/7470997/replace-german-characters-umlauts-accents-with-english-equivalents — BTC, Mar 12 '18 at 12:57

dahlbyk · Answer 1 · 2018-11-08T16:02:19.623

39

If you need to use this on larger strings, multiple calls to Replace() can get inefficient pretty quickly. You may be better off rebuilding your string character-by-character:

var map = new Dictionary<char, string>() {
  { 'ä', "ae" },
  { 'ö', "oe" },
  { 'ü', "ue" },
  { 'Ä', "Ae" },
  { 'Ö', "Oe" },
  { 'Ü', "Ue" },
  { 'ß', "ss" }
};

var res = germanText.Aggregate(
              new StringBuilder(),
              (sb, c) => map.TryGetValue(c, out var r) ? sb.Append(r) : sb.Append(c)
              ).ToString();

edited Nov 08 '18 at 16:02

answered Aug 13 '09 at 12:37

dahlbyk

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6

Good solution. I've extended it to handle all of ISO-8859-1: http://codepad.org/dUMpGlgg – primo Feb 01 '17 at 09:19
shorter: `res = text.Aggregate(new StringBuilder(), (sb, c) => map.TryGetValue(c, out string r) ? sb.Append(r) : sb.Append(c)).ToString();` ;) – AntiHeadshot Nov 08 '18 at 15:31
Updated! Love the evolution of C# with these nice little shortcuts. – dahlbyk Nov 08 '18 at 16:03

score 11 · Answer 2 · answered Aug 13 '09 at 12:16

Do just want a mapping of german umlauts to the two-letter (non-umlaut) variant? Here you go; untested, but it handles all german umlauts.

String replaceGermanUmlauts( String s ) {
    String t = s;
    t = t.Replace( "ä", "ae" );
    t = t.Replace( "ö", "oe" );
    t = t.Replace( "ü", "ue" );
    t = t.Replace( "Ä", "Ae" );
    t = t.Replace( "Ö", "Oe" );
    t = t.Replace( "Ü", "Ue" );
    t = t.Replace( "ß", "ss" );
    return t;
}

score 4 · Answer 3 · answered Aug 13 '09 at 12:11

I can't think of any automatic way to do this, so I believe you'd have to do it manually.

ie.

string GermanString = "äö";
GermanString = GermanString.Replace("ä", "ae");
GermanString = GermanString.Replace("ö", "oe");

How many characters are there? All vowels, in upper and lower case, so, 10? Shouldn't be too much of a job.

score 0 · Answer 4 · answered Aug 13 '09 at 12:15

0

How about using string.Replace:

string germanText = "Mötörhead";
string replaced = germanText.Replace("ö", "oe");

(okay, not a real German word, but I couldn't resist)

You can chain calls to Replace like this

someText.Replace("ö", "oe").Replace("ä", "ae").Replace("ö", "oe")...

answered Aug 13 '09 at 12:15

Mark Seemann

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It's actually M**o**törhead ;) – Otto Abnormalverbraucher Oct 28 '14 at 16:42

Andreas Ahlen · Answer 5 · 2019-10-18T06:41:52.053

This class removes diacritic characters (é, ì, è, etc.) and replaces umlauts and the German "ß" with their equivalents "ae (ä)", "oe (ö)", "ue (ü)" and "ss (ß)".

public sealed class UmlautConverter
{
    private Dictionary<char, string> converter = new Dictionary<char, string>()
    {
        {  'ä', "ae" },
        {  'Ä', "AE" },
        {  'ö', "oe" },
        {  'Ö', "OE" },
        {  'ü', "ue" },
        {  'Ü', "UE" },
        {  'ß', "ss" }
    };

    string value = null;
    public UmlautConverter(string value)
    {
        if (!string.IsNullOrWhiteSpace(value))
        {
            this.value = value;
        }
    }
    public string RemoveDiacritics()
    {
        if (string.IsNullOrWhiteSpace(value))
        {
            return null;
        }

        string normalizedString = this.value.Normalize();

        foreach (KeyValuePair<char, string> item in this.converter)
        {
            string temp = normalizedString;
            normalizedString = temp.Replace(item.Key.ToString(), item.Value);
        }

        StringBuilder stringBuilder = new StringBuilder();

        for (int i = 0; i < normalizedString.Length; i++)
        {
            normalizedString = normalizedString.Normalize(NormalizationForm.FormD);
            string c = normalizedString[i].ToString();
            if (CharUnicodeInfo.GetUnicodeCategory(Convert.ToChar(c)) != UnicodeCategory.NonSpacingMark)
            {
                stringBuilder.Append(c);
            }
        }
        return stringBuilder.ToString();
    }

    public bool HasUmlaut()
    {
        if (string.IsNullOrWhiteSpace(value))
        {
            return false;
        }

        foreach (KeyValuePair<char, string> item in this.converter)
        {
            if (this.value.Contains(item.Key.ToString()))
            {
                return true;
            }
        }

        return false;
    }
}

Usage:

Console.WriteLine(new UmlautConverter("Nürnberger Straße").RemoveDiacritics()); // Nuernberger Strasse

        Console.WriteLine(new UmlautConverter("Größenwahn").RemoveDiacritics()); // Groessenwahn
        Console.WriteLine(new UmlautConverter("Übermut").RemoveDiacritics()); // UEbermut
        Console.WriteLine(new UmlautConverter("Università").RemoveDiacritics()); // Universita
        Console.WriteLine(new UmlautConverter("Perché").RemoveDiacritics());// Perche
        Console.WriteLine(new UmlautConverter("être").RemoveDiacritics()); // etre

There is a minor bug in the "Übermut" case replacing "Ü" with "UE" instead of Ue". But this can be easily fixed. Enjoy :)

How do i replace accents (german) in .NET

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