- date_diff: documentation ( source)
- var_dump: documentation ( source)
- date_create: documentation ( source)
<?php
$date1=date_create("2013-03-15");
$date2=date_create("2013-12-12");
$diff=date_diff($date1,$date2);
var_dump(datediffInWeeks('6/4/2013', '1/2/2013'));// 21