use strict;
my $str = '<p>111 222 333</p>
<li>111 222 333</li>
<h1>111 222 333</h1>
<h2>111 222 333</h2>
<strong>111 222 333</strong>
<p><strong>111 222 333</strong></p>
<p>111 <a href="">222</a> 333</p>';
my $regex = qr~<(a|h1)\b.*?</\1>(*SKIP)(*F)|(222)~sip;
my $subst = '<a href="#link">\\2</a>';
my $result = $str =~ s~$regex~$subst~rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html