递归函数不附加到数组

Question

I've got a function that generates a matrix of date pairs. specifically, it takes two dates and adds the 31 day ranges to an array, so roughly, it would look like: [[date, date+31], [date, date+31], ...]

I'm using a recursive function to do it:

public function getBatchDates(Carbon $start, Carbon $end, array $arr) {
        $setEnd = Carbon::createFromTimestamp($start->getTimestamp())->addDays(31);
        if($setEnd->greaterThanOrEqualTo($end)) {
            $setEnd = $end;
            array_push($arr, array($start, $setEnd));
            return;
        }

        array_push($arr, array($start, $setEnd));

        $this->getBatchDates($setEnd, $end, $arr);
}

Now, when I debug the test that calls this function, it seems to work correctly:

However, the test, which is roughly as follows:

$array = array();
getBatchDates(new Carbon("first day of December 2015"),Carbon::now(), $array);

$this->assertNotNull($array);
$this->assertGreaterThan(0, sizeof($array));

It fails, because the $array is 0-length. Is there something I'm missing, the debugger makes it look like things are working.

Answer 1

Arrays in PHP are not passed into functions by reference, but by value. You'll need to either change the function signature to public function getBatchDates(Carbon $start, Carbon $end, array &$arr) (I think) or return the modified array.