Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks, I am writing a script to take data from a web page and validate it. Most of the script is done, including the length validation. The only bit i am stuck on as i do not understand perl all that well is the validation of symbols. The field $username must have either characters i.e 'bob' or characters and digits i.e 'bob1' but not just digits i.e '1234565'. It cannot have any symbols either, only _- are to be accepted i.e for usernames 'bob-jones' or 'tom_frank'. The current piece of code i have below does not do exactly what i want it to do, but if somebody could modify it, so that i can plonk it back into my script i would be eternaly gratefull. 
 if ($display !~ /^\w*$/) {
    $message = $message.$errmsg ;
    $found_err = 1 ; }

[download]
Thank-you for reading this, and i know for most of you this is simple - but i'm rubbish at this type of thing.

Replies are listed 'Best First'.
Re: Subscription Stuff
by DamnDirtyApe (Curate) on Aug 03, 2002 at 17:44 UTC 
    unless (    ( $display =~ /^[\w-]+$/ ) # Can contain chars, digits, _ 
+and -
         && ( $display !~ /^\d+$/    ) # But not just digits
       )
{
    # String failed to validate.
}

    [download]

    If you're having trouble with the regexps presented, I suggest you give perlre a good long read -- they only get worse from here. :-)


    _______________
    DamnDirtyApe 
    Those who know that they are profound strive for clarity. Those who
would like to seem profound to the crowd strive for obscurity.
            --Friedrich Nietzsche
[reply]
[d/l]
Re: Subscription Stuff
by Zaxo (Archbishop) on Aug 03, 2002 at 17:18 UTC

    You want to match at least one, so use '+' instead of '*' as the quantifier. Having passed that, you want to match a non-digit:

    sub is_word_with_nondigit {
#    $_ = shift;
#    /^\w+$/ and /\D/;
    $_[0] =~ /^\w+$/ and $_[0] =~ /\D/;
}

    [download]

    A different quantifier may be used if you want a minimum length, like /^\w{4,}$/

    Update: Modified code to untaint the sub's argument, instead of checking a copy. If you don't like side effects use the commented-out version.

    After Compline,
    Zaxo

[reply]
[d/l]
Re: Subscription Stuff
by Cine (Friar) on Aug 03, 2002 at 17:06 UTC
    Whats wrong with all the answers you got in 186609??

    T I M T O W T D I
[reply]
[d/l]
      i am stupid, i couldn't integrate any of those answers into the script i already have. also i need it to validate wether just number have been entered
[reply]
Re: Subscription Stuff
by BronzeWing (Monk) on Aug 03, 2002 at 21:40 UTC

    I felt an itch to try to do this in one regex. Admittedly it's a longer string than checking with two short ones, but here's a single regex that I believe does the same thing:

    m/^[\w-]*[A-Z\-\_][\w-]*$/i

    Basically, "There must be a single character that is a letter, a dash, or an underscore. It can also have any number of characters before or after it if none of those characters are anything but word characters (letters or underscores) or dashes."

    -BronzeWing

[reply]
[d/l]

Back to Seekers of Perl Wisdom