<H1>(<[A-Za-z0-9]+>)

[download]
matches the ABCD in <H1>ABCD</H1>?

I think not. Remove the < and >, and add an H1 closing tag to clarify, ie: 

<H1>([A-Za-z0-9]+)</H1>

[download]

Or if you don't mind it picking up underscores as well as letters and numbers, you can use the much more succint: 

<H1>(\w+)</H1>

[download]
\w means match a word character. I suggest you do a little search on parsing html in the Super Search, or look at the HTML::Parser module, discussed here

You may want to also add modifiers to your regex, ie: 


    if ( m!$catreg!is ) {

[download]
the i makes it case insensitive (picks up h1 and H1), the s make the regex treat the whole string/page as one line, matching H1's created by that lovely editor, Dreamweaver, eg: 
                    <h1>I am a heading
                    created by Dreamweaver</h1>

[download]

<rant>
(not that Dreamweaver users ever seem to use <Hn> when <p><b><font size=6> will do instead :)
</rant>

cLive ;-)

Update: I missed that you were matching a possible tag before the match you use (see below). I strongly suggest you look at a parsing module if you don't know whether tags will contain tags or not!

In reply to Re: (**corrected**) What Does This Line Do? by cLive ;-)
in thread (**corrected**) What Does This Line Do? by sfrattura

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.