PHP removing all array items

Question

Can anyone please help me to understand and fix; why the following code is clearing all the items from the array. Code is meant to remove all items recursively in the array that do not have '_label' in their key

function checkiflabel($item,$key){
   if(strpos($key,'_label')!==false)
        return true;
    else
        return false;
}
function walk_recursive_remove (array $array, callable $callback) {
    foreach ($array as $k => $v) {
        if (is_array($v)) {
            if (($callback($v, $k))==false)
                unset($array[$k]);
            else
                $array[$k] = walk_recursive_remove($v, $callback);
        } else {
            if (($callback($v, $k))==false) {
                unset($array[$k]);
            }
        }
    }
    return $array;
}

I am calling this using

$data = walk_recursive_remove($data1,'checkiflabel');
print_r($data); die;

Its shows empty array and for sure $data1 is an array and has values because if I change

if (($callback($v, $k))==false) 

to

if ($callback($v, $k))

it does remove all items that have _label and the rest items are fine. Below is the print_r for $data1 with some data obfuscation

Array ( [1] => Array (
    [gridReviewerDecision] => ACCEPTED
    [gridReviewerDecision_label] => Accepted
    [gridReviewerComment] => ok
    [gridReviewerComment_label] => ok
    [gridReviewerAcceptedAmount] => 100
    [gridReviewerAcceptedAmount_label] => 100
    [gridUploadFilesByReviewer] => Array (
        [0] => Array (
            [appDocUid] => 5810427715e892c81ab34c8030653093
            [name] => drawing.pdf
            [version] => 1
            )
        )
    [gridUploadFilesByReviewer_label] => Array (
        [0] => drawing.pdf
        )
    [gridContest] => 1
    [gridContest_label] => true
    [gridTypeOfMOtive] => AAAAA
    [gridTypeOfMOtive_label] => BBBBB
    [gridComment] => test 1
    [gridComment_label] => test 1
    [gridUploadFiles] => Array (
        [0] => Array (
            [appDocUid] => 3735522335e892c08eefa43074490443
            [name] => drawing.jpg
            [version] => 1
            )
        [1] => Array (
            [appDocUid] => 6071415935e892c10331426048606075
            [name] => drawing.png
            [version] => 1
            )
        )
    [gridUploadFiles_label] => Array (
        [0] => drawing.jpg
        [1] => drawing.png
        )
    [gridContestationAmount] => 100
    [gridContestationAmount_label] => 100
    [DA_PLATFORME] => XXXXXX
    [DA_PLATFORME_label] => XXXXXX
    [EAN] => 3257980158208
    [EAN_label] => 3257980158208
    [DESIGNATIONARTICLE] => ZZZZZZ
    [DESIGNATIONARTICLE_label] => ZZZZZZ
    [VA] => 00
    [VA_label] => 00
    [DPROMORPERM] => P
    [DPROMORPERM_label] => P
    [CODERUPTURECOMMANDE] => 06
    [CODERUPTURECOMMANDE_label] => 06
    [DATELIVR] => 04/12/09
    [DATELIVR_label] => 04/12/09
    [NOCDE] => 12336422
    [NOCDE_label] => 12336422
    [RELIQUAT] => 
    )
  )

Answer 1

EDIT My misunderstanding - you are working with associative arrays. This was not initially clear to me.

When I test your posted code against the following array:

$a = [
    'test' => 'a',
    'test2' => 'b',
    'test3' => 'c',
    'test_label' => 'd',
    'test_label_2' => [
        'test_label_3' => 'e',
        'test4' => [
            'test_label_4' => 'f'
        ]
    ]
];

It seems to do what you expect.

OUTPUT:
Array (
     [test_label] => d
     [test_label_2] => Array (
          [test_label_3] => e
     )
)

---

Original Answer

The issue is with the order of parameters.

    if (($callback($v, $k))==false) {
        unset($array[$k]);
    }

In this case, $v is the string, and $k is the array index. So, your checkiflabel method is comparing the numeric array indexes to a string.

The solution is simply to reverse the order that you call the method with.

    if (($callback($k, $v))==false) {
        unset($array[$k]);
    }

As a small tip, in the future when you run into similar issues: You would've quickly noticed this by simply adding a var_dump to the checkiflabel method to ensure that the parameters are as you expected them to be! :)