Could it just be a version issue? The code you posted works fine for me:

use warnings;
use strict;
use XML::LibXML;

my $XML = <<'_END_XML_';
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html [ <!ENTITY atad "data"> ] >
<html xmlns="http://www.w3.org/1999/xhtml">
<div class="&atad;" id="Hello" />
<div class="&atad;" id="World" />
</html>
_END_XML_

print $XML::LibXML::VERSION, " ",
    XML::LibXML::LIBXML_DOTTED_VERSION, " ",
    XML::LibXML::LIBXML_VERSION, " ",
    XML::LibXML::LIBXML_RUNTIME_VERSION, "\n";
my $dom = XML::LibXML->load_xml(string=>$XML);
my $xpc = XML::LibXML::XPathContext->new;
$xpc->registerNs(xh => 'http://www.w3.org/1999/xhtml');
for my $div ($xpc->findnodes('//xh:div[@class="data"]', $dom)) {
    print "1:", $div->{id}, "\n"
}
for my $div ($xpc->findnodes('//xh:div', $dom)) {
    print "2:", $div->{id}, " ", $div->{class}, "\n"
}

__END__

2.0129 2.9.1 20901 20901
1:Hello
1:World
2:Hello data
2:World data

[download]

In reply to Re^4: Parsing HTML/XML with Regular Expressions by haukex
in thread Parsing HTML/XML with Regular Expressions by haukex

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.