use strict;
use warnings;
use XML::Twig;

my $xfile = <<EOF;
<people>
    <person><name>Jane Doe</name><age>42</age></person>
    <person><name>John Doe</name><age>43</age></person>
    <person><name>Foo Bar</name><age>43</age></person>
</people>
EOF

my $t= new XML::Twig();
$t->parse($xfile);
my $people  = $t->root();
my @persons = $people->children('person');
for (@persons) {
    my $name = $_->first_child('name')->text();
    my $age  = $_->first_child('age' )->text();
    if ($age == 43) { print "$name is $age\n" }
}

__END__
John Doe is 43
Foo Bar is 43