PHP - Unzip an uploaded file using php

<?php

     $zip = new ZipArchive;
     $res = $zip->open('my_zip_file.zip');
     if ($res === TRUE) {
         $zip->extractTo('my_extract_to_dir/');
         $zip->close();
         echo 'ok';
     } else {
         echo 'failed';
     }
?> 

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