Another option is HTML::TreeBuilder, which may be more suited towards your goal. Replacing existing tags can be tricky, given the dozens of variants that people may use in their HTML, some valid, most invalid. Let the module figure it out, not a hand-rolled regex.

merlyn has a recent article called "The Wrong Parser for the Right Reasons" which covers something very similar. Give it a read, and see if it suits your goal. A brief synopsis from the top of the article:

More and more these days, you get faced with a problem with angle brackets somewhere in the data. How do you find what you're looking for in HTML or XML data?

At first glance, the question has an obvious answer. If you have an HTML task, you use HTML::Parser or some derived or wrapper class. If you have an XML task, you use XML::Parser or XML::LibXML. But maybe the obvious answer isn't always the best. Let's look at a couple of cases.


In reply to Re: Regex's on Text of HTML (using HTML::Parser) by hacker
in thread Regex's on Text of HTML (using HTML::Parser) by rjahrman

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.