Calculating a date interval with strtotime()

 
<?php
$birthday = 'March 10, 2010';
$whoopee_made = strtotime("$birthday - 9 months ago");
?>

1.	Checking a date range
2.	int strtotime ( string time [, int now] ) converts strings to a timestamp
3.	Using strtotime()
4.	Using strtotime() with a starting epoch timestamp
5.	Find the First monday on or after November 1, 2008
6.	Find weekday
7.	Finding the Date for a Weekday
8.	Getting the Day and Week of the Year
9.	If PHP is unable to convert your string into a timestamp, it will return -1.
10.	Obtaining the Difference Between Two Dates
11.	Subtracts a year from a given timestamp

Calculating a date interval with strtotime() : strtotime « String « PHP