From: dblack@...
Date: 2006-09-03T21:23:23+09:00
Subject: Re: RegExp issues....

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Hi -

On Sun, 3 Sep 2006, Gareth Adams wrote:

> 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 string=
s
> /conatining/ a letter, digit hyphen or underscore:
>
> irb(main):001:0> /[A-Z0-9_-]/ =3D~ "=C2=A3$%^"
> =3D> nil
> irb(main):002:0> /[A-Z0-9_-]/ =3D~ "=C2=A3$0%^"
> =3D> 2
>
> You probably want something like
>
> /^[\w-]+$/

Eric Hodel already suggested using \A and \Z, and I just suggested \A
and \z.  The problem with ^ and $ is that they match the beginnings
and endings of lines, but not the whole string.


David

--=20
                   David A. Black | dblack@wobblini.net
Author of "Ruby for Rails"   [1] | Ruby/Rails training & consultancy [3]
DABlog (DAB's Weblog)        [2] | Co-director, Ruby Central, Inc.   [4]
[1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com
[2] http://dablog.rubypal.com    | [4] http://www.rubycentral.org
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