Question

Comment is the output I’m seeing. Help!

echo date("Y-m-t", strtotime("2012-07-31 -1 month")); //2012-07-31
echo date("Y-m-t", strtotime("2012-07-31 -2 month")); //2012-05-31

July has 31 days, so it can’t be processing it as August 1, right? Even if it were, the second line should work. Right?!

Thanks!

Answer 1

What’s happening here is, “7-31” minus one month comes out as “6-31”, which translates to “7-1”, which – asking for the last day of the month – comes out as “7-31”.

When you want to do month math, it’s almost always, if not always, better to build the time using mktime.

$month = 7;
echo date("Y-m-t", mktime(0, 0, 0, $month - 1, 1, 2012)); //2012-06-30

Note that when doing month math in mktime, always give ‘1’ as the day. Or really anything as long as it’s 28 or lower.