title: d/m/y to Y-m-d php stringtotime not working correctly
body: <p>I have a date string of the format <code>d/m/y</code> e.g. <code>22/02/13</code></p>
  
  <p>I would like to echo this string as <code>Y-m-d</code> but using the following code, it is not working.</p>
  
  <pre><code>$d = '22/02/13';
  echo date('Y-m-d', strtotime($d));
  </code></pre>
  
  <p>Output: <code>1970-01-01</code></p>
  
  <p>What am I doing wrong? Do I have to explode this by <code>/</code> as the delimiter and do it manually or is there a simpler / more elegant solution?</p>