Recursive function never return my temp array

Question

I'm assuming my loop keeps looping and clearing my temp array, but not sure how to fix this. At the end, return is always empty.

How can I correctly return my temp array?

Data set:

Array(
    [0] => Array(
            [0] => Array(
                    [id] => 55
                    [parent] => 49
                )
            [1] => Array(
                    [id] => 62
                    [parent] => 50
                )
            [2] => Array(
                    [id] => 64
                    [parent] => 51
                )
        )
    [1] => Array(
            [0] => Array(
                    [id] => 49
                    [parent] => 0
                )
        )
)

Function:

<?php

    $patterns = function($array, $temp = array(), $index = 0, $parent = 0) use(&$patterns) {
        if($index < count($array)) {
            foreach($array[$index] as $sub) {
                if($index == 0 || $parent == $sub['id']) {
                    $temp[$index] = $sub['id'];
                    $patterns($array, $temp, $index + 1, $sub['parent']);
                }
            }
        }

        if($index >= count($array) && $parent == 0) {
            print_r($temp); // correct result does display here!

            return $temp; // this return gives no return
        }
    };

    print_r($patterns($dataset));

?>

print_r returns Array ( [0] => 55 [1] => 49 )

expected output please. – Tintu C Raju Nov 18 '15 at 03:57 — Tintu C Raju, Nov 18 '15 at 03:57

score 1 · Accepted Answer · answered Nov 18 '15 at 04:01

On line 8, return the result of $patterns($array, $temp, ...) only if it is not null. Also, don't set the result to the $temp variable, so you don't override it if the result is null.

Like so:

$temp2 = $patterns($array, $temp, $index + 1, $sub['parent']);

if (isset($temp2)) {
    return $temp2;
}

If the condition on line 13 fails, it'll return null, and that's not the result you want, so you have to keep going if it is null.

By the way, I wasn't able to reproduce your code giving the correct answer where it says // correct result does display here!. To make it work I had to change lines 5 & 6 to:

foreach($array[$index] as $key => $sub) {
    if ($key == 0 || $parent == $sub['id']) {

And I also had to change line 13 to:

if($index >= count($array)-1 && $parent == 0) {

thank you so much! Line 5, 6, and 13 changes broke the logic. The returning the variable worked! — HelpNeeder, Nov 18 '15 at 04:19
Ah just realized that my datA set is already reversed so no need to reverse again. This is the reason you couldn't get the result. My mistake. — HelpNeeder, Nov 19 '15 at 23:22

score 0 · Answer 2 · answered Nov 18 '15 at 03:32

0

What happens when you modify line #6 and add "return" to the beginning of it?

    RETURN $patterns($array, $temp, $index + 1, $sub['parent']);

answered Nov 18 '15 at 03:32

John Doe

905
8
9

Actually, I see something. Your line "return $temp" isn't inside any function that I can see. It's outside of the $patterns function. Your value of $temp is set at that point - but there's nowhere to "return" it to. Is that it? – John Doe Nov 18 '15 at 03:59

Recursive function never return my temp array

2 Answers2