How to extract/ unzip ZIP / GZIP file using PHP

How to extract ZIP / GZIP file using PHP

<?php
$zip = new ZipArchive;
$res = $zip->open('myproject.zip');
if ($res === TRUE) {
  $zip->extractTo('/var/www/html/directoryname/');
  $zip->close();
  echo 'woot!';
} else {
  echo 'doh!';
}
?>