regex to replace all non alphanumeric characters code example

Example 1: c# filter non alphanumeric characters

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

Example 2: remove all non alphabetic characters from string c#

var cleanString = new string(dirtyString.Where(Char.IsLetter).ToArray());