Question

I need to compare 2 strings in C# and treat accented letters the same as non-accented letters. For example:

string s1 = 'hello'; string s2 = 'héllo';  s1.Equals(s2, StringComparison.InvariantCultureIgnoreCase); s1.Equals(s2, StringComparison.OrdinalIgnoreCase); 

These 2 strings need to be the same (as far as my application is concerned), but both of these statements evaluate to false. Is there a way in C# to do this?

Answer 1

FWIW, knightfor’s answer below (as of this writing) should be the accepted answer.

Here’s a function that strips diacritics from a string:

static string RemoveDiacritics(string text) {   string formD = text.Normalize(NormalizationForm.FormD);   StringBuilder sb = new StringBuilder();    foreach (char ch in formD)   {     UnicodeCategory uc = CharUnicodeInfo.GetUnicodeCategory(ch);     if (uc != UnicodeCategory.NonSpacingMark)     {       sb.Append(ch);     }   }    return sb.ToString().Normalize(NormalizationForm.FormC); } 

More details on MichKap’s blog (RIP…).

The principle is that is it turns ‘é’ into 2 successive chars ‘e’, acute. It then iterates through the chars and skips the diacritics.

"héllo" becomes "he<acute>llo", which in turn becomes "hello".

Debug.Assert("hello"==RemoveDiacritics("héllo")); 

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Note: Here’s a more compact .NET4+ friendly version of the same function:

static string RemoveDiacritics(string text) {   return string.Concat(        text.Normalize(NormalizationForm.FormD)       .Where(ch => CharUnicodeInfo.GetUnicodeCategory(ch)!=                                     UnicodeCategory.NonSpacingMark)     ).Normalize(NormalizationForm.FormC); }