title: Calculating age from date of birth in PHP
body: <p>What's the most precise function you have come across to work out an age from the users date of birth. I have the following code and was wondering how it could be improved as it doesn't support all date formats and not sure if it's the most accurate function either (DateTime compliance would be nice).</p>
  
  <pre><code>function getAge($birthday) {
      return floor((strtotime(date('d-m-Y')) - strtotime($date))/(60*60*24*365.2421896));
  }
  </code></pre>