title: finding next month, previous month giving wrong result
body: <p>I want to find 2 months after current month and previous month. I have coded as below,</p>
  
  <pre><code>$current = strtotime(date('m',time()) . '-01 00:00:01');
  $next_month = date('m', strtotime('+1 month', $current));
  $next_next_month = date('m', strtotime('+2 month', $current));
  $previous_month = date('m', strtotime('-0 month', $current));
  
  echo $previous_month.$next_month.$next_next_month;
  
  output : 01 02 03
  </code></pre>
  
  <p>I want to get the result from current month. And the expected output is <code>04 05 06</code>.</p>
  
  <p>How to achieve this result. Is there any solution. Thankyou.</p>