Changing values in a multi-dimensional array via reference (in PHP)?

Question

The following PHP function finds the node in the multi-dimensional array by matching its key:

<?php
function & findByKey($array, $key) {
    foreach ($array as $k => $v) {
        if(strcasecmp($k, $key) === 0) {
            return $array[$k];
        } elseif(is_array($v) && ($find = findByKey($array[$k], $key))) {
            return $find;
        }
    }

    return null;
}


$array = [
    'key1' => [
        'key2' => [
            'key3' => [
                'key5' => 1
            ],
            'key4' => '2'
        ]
    ]
];

$result = findByKey($array, 'key3');

I want the function to return a reference to the node so that if I change $result then the original $array also changes (like Javascript objects).

<?php
array_splice($result, 0, 0, '2');

//Changes $array also since the `$result` is a reference to:
$array['key1']['key2']['key3']

How can I do this?

Tried using array_column ? That should be a start

Rotimi
– Rotimi

2017-08-23 11:49:18 +00:00
Commented Aug 23, 2017 at 11:49 — Rotimi
– Rotimi, Commented Aug 23, 2017 at 11:49

BizzyBob · Accepted Answer · 2017-08-23 12:59:19Z

1

You need to do two things:

1) specify your $array parameter as a reference:

function & findByKey(&$array, $key) {

2) assign the variable $result by reference using the &:

$result = &findByKey($array, 'key3');

Since you are calling your function recursively, you need to also assign $find by reference as well.

altogether:

function & findByKey(&$array, $key) {
    foreach ($array as $k => $v) {
        if(strcasecmp($k, $key) === 0) {
            return $array[$k];
        } elseif(is_array($v) && ($find = &findByKey($array[$k], $key))) {
            return $find;
        }
    }

    return null;
}


$result = &findByKey($array, 'key3');
$result = 'changed';
print_r($array);

edited Aug 23, 2017 at 12:59

answered Aug 23, 2017 at 12:34

BizzyBob

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