How to check if only chosen characters are in a string?

Question

What\'s the best and easiest way to check if a string only contains the following characters:

abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_         


        

Answer 1

Use a regular expression, like this one:

^[a-zA-Z0-9]+$

http://regexlib.com/REDetails.aspx?regexp_id=1014