When importing dates or timestamps out of mySql you might want to rank the dates on time. For this you ofcourse want to use numbers. It is a bit unclear on php.net to convert dates to numbers or strings. However, I found out by searching in forums and here is how to do it (very easy though)
Just use the function strtotime
for example: $date='Fri, 04 May 2007 11:50:18 +0200'; echo $number=strtotime($date);
It will convert the date (and time!):
Fri, 04 May 2007 11:50:18 +0200
into a number like this:
1178272218<comments />