PHP ftp_mdtm() Function

<?php
// connect and login to FTP server
$ftp_server = "ftp.example.com";
$ftp_conn = ftp_connect($ftp_server) or die("Could not connect to $ftp_server");
$login = ftp_login($ftp_conn, $ftp_username, $ftp_userpass);

$file = "somefile.txt";

// get the last modified time
$lastchanged = ftp_mdtm($ftp_conn, $file);
if ($lastchanged != -1)
  {
  echo "$file was last modified on : " . date("F d Y H:i:s.",$lastchanged);
  }
else
  {
  echo "Could not get last modified";
  }

// close connection
ftp_close($ftp_conn);
?>