[RESOLVED] Calculating days elapsed between two dates specified by strings

[sneakyimp]

Given two dates (e.g., '2008-06-30' and '2008-06-01') I'm wondering the easiest way to calculate the number of days that have elapsed. I wrote this function but can't help wondering if there's like a one-line piece of PHP kung-fu that might be shorter and more reliable. I have a weird feeling this one might break in 2038 or whatever:

/**
 * This routine can take two strings representing dates
 * and return the number of days that have elapsed between
 * the two.  By default, it rounds to the nearest day.
 * NOTE:  It relies on the strtotime() function to parse
 * the date strings
 * @param string $time1 The starting time
 * @param string $time2 The ending time
 * @param int $precision Round to this number of decimal points
 */
function get_days_elapsed($time1, $time2, $precision=0) {
	$t1 = strtotime($time1);
	if ($t1 === FALSE) return FALSE;
	$t2 = strtotime($time2);
	if ($t2 === FALSE) return FALSE;

$elapsed_seconds = $t2 - $t1;
$elapsed_days = round(($elapsed_seconds) / (60*60*24), $precision);

return $elapsed_days;
}

[NogDog]

The way you did it is probably the fastest (dividing by the number of seconds in a day), but can result in occasional errors if the input date/times cross a daylight savings time change (and depending on what times are being used). You can use a loop on strtotime("+1 day") or something similar, but that's kind of inefficient. (See http://www.charles-reace.com/PHP_and_MySQL/Time_Difference/ for an example).

There is a PEAR DATE package that includes several "date arithmetic" methods, but I've not yet messed around with it so have no pro/con comments.

[sneakyimp]

Thanks NogDog. I suppose my method will be good enough. The max impact I can see due to DST considerations in this case is 1/24 of a day which would be handled by the rounding.