PHP: Set value of nested array using variable as key

Question

Lets say i have this kind of code:

    $array = [
        'a'=> [
            'b' => [
                'c'=>'some value',
            ],
        ],
    ];

    $array['a']['b']['c'] = 'new value';

Of course this is working, but what i want is to update this 'c' key using variable, something like that:

$keys = '[a][b][c]';
$array{$keys} = 'new value';

But keys are treatening as string and this is what i get:

$array['[a][b][c]'] = 'new value';

So i would like some help, to show me the right way to make this work without using eval().

By the way, there can be any number of array nests, so something like this is not a good answer:

$key1 = 'a';
$key2 = 'b';
$key3 = 'c';
$array[$key1][$key2][$key3] = 'new value';

Answer 1

It isn't the best way to define your keys, but:

$array = [];
$keys = '[a][b][c]';
$value = 'HELLO WORLD';

$keys = explode('][', trim($keys, '[]'));
$reference = &$array;
foreach ($keys as $key) {
    if (!array_key_exists($key, $reference)) {
        $reference[$key] = [];
    }
    $reference = &$reference[$key];
}
$reference = $value;
unset($reference);

var_dump($array);

If you have to define a sequence of keys in a string like this, then it's simpler just to use a simple separator that can be exploded rather than needing to trim as well to build an array of individual keys, so something simpler like a.b.c would be easier to work with than [a][b][c]

Demo