Ok... I'll try my best to explain the problem. I have the following function:

function fixdate(&$month, &$year) {
	if ($month < 1) {
		$month = 12;
		$year--;
	} elseif ($month > 12) {
		$month = 1;
		$year++;
	}
}

So far so good, the function itself works ok. But when I try to do the following:

	fixdate($prevmonth = ($month - 1), $prevyear = $year);

I get this error:

	Fatal error: Only variables can be passed by reference in C:\foo.php on line 181

However, this code works as expected:

	fixdate($prevmonth = ($month - 1), $prevyear = ($year + 0));

You'd expect the first code ($prevyear = $year) to work as well, wouldn't you? The reason I use $prevyear = $year and not just pass $year is because I need to keep the value of $year after the function has executed.

This might be related to the way PHP copies variables, I'm not sure. If you need any more information, let me know. :)

Thanks,
Chen