How do I remove all non alphanumeric characters from a string except dash?

Using System.Linq

string withOutSpecialCharacters = new string(stringWithSpecialCharacters.Where(c =>char.IsLetterOrDigit(c) || char.IsWhiteSpace(c) || c == '-').ToArray());

I could have used RegEx, they can provide elegant solution but they can cause performane issues. Here is one solution

char[] arr = str.ToCharArray();

arr = Array.FindAll<char>(arr, (c => (char.IsLetterOrDigit(c) 
                                  || char.IsWhiteSpace(c) 
                                  || c == '-')));
str = new string(arr);

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When using the compact framework (which doesn't have FindAll)

Replace FindAll with¹

char[] arr = str.Where(c => (char.IsLetterOrDigit(c) || 
                             char.IsWhiteSpace(c) || 
                             c == '-')).ToArray(); 

str = new string(arr);

---

¹ Comment by ShawnFeatherly

Replace [^a-zA-Z0-9 -] with an empty string.

Regex rgx = new Regex("[^a-zA-Z0-9 -]");
str = rgx.Replace(str, "");

You can try:

string s1 = Regex.Replace(s, "[^A-Za-z0-9 -]", "");

Where s is your string.