title: Add days to a date in PHP
body: <p>Is there any php function available where I can add days to a date to make up another date? For example, I have a date in the following format:
  27-December-2011</p>
  
  <p>If I add 7 to the above, it should give:
  03-January-2012.</p>
  
  <p>Many thanks</p>