PHP: Backup a folder to a zip file

<?php
include('pclzip.lib.php');
//zip file name
$new_zip= new PclZip('backup.zip');
//backup theimages folder
$file_list = $new_zip->create('images/');
if ($file_list == 0)
{
die("Error : ".$new_zip->errorInfo(true));
}
echo "Successfully created zip file";
?>