title: Calculate the date difference in the given format in PHP4
body: <p>I need a function in php4 that will calculate the date difference in the provided date format.
  eg.</p>
  
  <pre><code>$date1 = "2011-08-24 10:03:00";
  $date2 = "2012-09-24 10:04:31";
  $format1 = "Y W" ; //This format should return the difference in Year and week.
  $format2 = "M D"; // This format should return the difference in Months and days.
  // The format can be any combination of Year,Month,Day,Week,Hour,Minute,Second.
  
  function ConvertDate($data1,$date2,$format) 
  </code></pre>
  
  <p>Please let me know if you need any more details on this.
  Thanks in advance.</p>