use XML::Simple;
my $xml = new XML::Simple;
$answers = $xml->XMLin('answers.xml');
$url = $answers->{answer}->[0]->{url}; 
print "$url";

##</code><code>##

<?xml version="1.0" encoding="UTF-8"?>
<file>
  <answer>
    <url>web 1</url>
  </answer>
  <answer>
    <url>web 2</url>
  </answer>
</file>

##</code><code>##

<?xml version="1.0" encoding="UTF-8"?>
<file>
  <answer>
    <url>web 1</url>
  </answer>
</file>