Disable special characters in usernames
 

Hello, i know that for disable special characters in username i should use a Regular Expression.

I need a Regular Expression that allow all characters of an english/european keyboard (for example A-Z 0-9 and|!"£$%&/()[]{}~=?^'?è+ùà?,.-é*§°ç;:_@#€ and spaces too) but not special characters like that αssу ♥, etc.

What Regular Expression should i use to do that?
Thanks in advance :)