เรื่องการเขียนข้อมูลเพิ่มใน xml สามารถเพิ่มต่อท้ายสุดได้หรือไม่

$filename="phoneBook.xml";
$contents = file($filename);
$lines="";
for($i=2;$i<count($contents);$i++) {
$lines .= $contents[$i];
}
$head = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n";
$head .= "<phone>\r\n";

$data = "<phones>\r\n";
$data .= "<Name>$name</Name>\r\n";
$data .= "<Office>$office</Office>\r\n";
$data .= "<Home>$home</Home>\r\n";
$data .= "<Mobile>$mobile</Mobile>\r\n";
$data .= "<Address>$address</Address>\r\n";
$data .= "<Position>$position</Position>\r\n";
$data .= "<Type>$type</Type>\r\n";
$data .= "</phones>\r\n";

$fp = fopen($filename,'w');
fwrite($fp, $head.$data.$lines);
fclose($fp);

echo "<h3>Record data complete</h3>";