title: PHP Week number
body: <pre><code>date_default_timezone_set('Europe/Helsinki');
  $now = strtotime('now'); // 1388430373
  $weekNumber = date('W', $now);
  var_dump($weekNumber);
  </code></pre>
  
  <p>Why this code shows <code>01</code>?<br>
  It's now 30th december 2013</p>
  
  <p>How to get <code>right</code> week number?</p>