From: Gareth Adams <gareth.adams@...>
Date: 2006-09-03T21:12:32+09:00
Subject: Re: RegExp issues....

Ben V. <comprug <at> gmail.com> writes:

> 
> I am trying to validate user input so it contains only letters, numbers, 
> underscores and dashes. I am using this regexp:/[A-Z0-9_-]/. However, 
> when I type in 'hello' in the field, it says that it doesn't match the 
> regexp, yet I'm sure that reg exp works for letters, numbers, and 
> underscores only. What am I doing wrong? Thanks for your help and time.
> 


No one else seems to have mentioned that that regex will match all strings
/conatining/ a letter, digit hyphen or underscore:

irb(main):001:0> /[A-Z0-9_-]/ =~ "贈$%^"
=> nil
irb(main):002:0> /[A-Z0-9_-]/ =~ "贈$0%^"
=> 2

You probably want something like

/^[\w-]+$/

Gareth