title: PHP Convert Local time to UTC DateTime
body: <p>I want to convert my local timezone dateTime to UTC timezone DateTime.</p>
  
  <pre><code>date_default_timezone_set('Asia/Calcutta');
  $datetime = "2016-05-05 18:33:00";
  echo date_default_timezone_get()."&lt;br&gt;"; // Asia/Calcutta
  date_default_timezone_set('UTC');
  echo date_default_timezone_get()."&lt;br&gt;"; //UTC
  echo $utcDateTime = date("Y-m-d H:i:s",strtotime($datetime));
  </code></pre>
  
  <p><strong>Current Output</strong></p>
  
  <pre><code>2016-05-05 18:33:00
  </code></pre>
  
  <p>But, Problem is do not convert local dateTime to UTC dateTime. It will give output as Local DateTime.</p>