calculate length between date to date

Hi all I have 2 variables here that store date start and date end, I want to compare the lenght between the start date and the end date, how would I do that? $dateStart = "$year" . "$mon" . "$date" ; ( for instance, it will return "20010102") $dateEnd = "$yearEnd" . "$monEnd" . "$dateEnd" ; ( for instance, it will return "20010201") How do I calculate the length between those 2 variables? Jack jacky@activelifestyle.com "There is nothing more rewarding than reaching the goal you set for yourself"