Regex Expressions for all non alphanumeric symbols

If you want to match non-alphanumeric symbols then just use \W|_.

Regex pattern = new Regex(@"\W|_");

This will match anything except 0-9 and a-z. Information on the \W character class and others available here (c# Regex Cheet Sheet).

• https://www.mikesdotnetting.com/article/46/c-regular-expressions-cheat-sheet

You could also avoid regular expressions if you want:

return s.Any(c => !char.IsLetterOrDigit(c))