while ($t =~ /<div id="724">(.*?)<\/div>/sg)
{
    print "$_\n" for $1 =~ /<p>(.+?)<\/p>/g;
}

##</code><code>##

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

my $t = <<'EOF';
...
<meta charset="UTF-8" />
...
EOF

my $dom = XML::LibXML->load_xml(string => $t);

print $_->to_literal . "\n" for $dom->findnodes('//div[@id="724"]/p');

##</code><code>##

 1:59 >perl 1798_SoPW.pl
aaa22
22
22
aaa22
aaa22
aafsdfsdfa22

 1:59 >