Hi All,
  I've written a new cgi configuration module that generates the HTML config update forms, verifies the input and saves the data as perl variables.
  For the verification I use regexp (obvious). Regexp have never been my strong point, although recently they have been making a lot more sense. I understand $1, $`, $&, $', etc. But I'm not sure if I'm doing some things right. For example I have a regexp that checks for path for illegal characters:- 
unless ($input->{$key} =~ /^[a-zA-Z]?:?[^\<\>\:\"\|\?\*]+$/) {
    die "Error";
}#unless

[download]
If I want to show the user what didn't match to cause the error I'm having to do another regexp:- 
unless ($input->{$key} =~ /^[a-zA-Z]?:?[^\<\>\:\"\|\?\*]+$/) {
    $input->{$key} =~ /[\<\>\:\"\|\?\*]/;
    die "Error, found $&";
}#unless

[download]
Am I doing it right? The ^a-zA-Z?:? is at the beginning as paths my be full windows paths. Although I get the feeling I problem mean ^(a-zA-Z:)? I'll have to test to be sure. Thinking about it I need yet another regexp so the error doesn't complain about the : in a c:/... 
unless ($input->{$key} =~ /^[a-zA-Z]?:?[^\<\>\:\"\|\?\*]+$/) {
    $input->{$key} =~ s/^[a-zA-Z]://;
    $input->{$key} =~ /[\<\>\:\"\|\?\*]/;
    die "Error, found $&";
}#unless

[download]
Sure there is an easier way to do it. Hoping one of you rexexp gurus will help.

Lyle

In reply to Showing why a Regexp didn't match by cosmicperl

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.