Reset array keys in multidimensional array, recursive, by reference

Question

I want to reset keys in a big, multidimensional array. I already found a solution which is actually work:

$fix_keys = function(array $array) use (&$fix_keys)
{
 foreach($array as $k => $val)
 {
 if (is_array($val))
 {
 $array[$k] = $fix_keys($val);
 }
 }
 return array_values($array);
};

and the problem is, if I pass big arrays to it, it becomes slow and memory consuming. What about refactoring with working references:

$fix_keys = function(array &$array) use (&$fix_keys)
{
 foreach($array as $k => &$val)
 {
 if (is_array($val))
 {
 $array[$k] = $fix_keys($val);
 }
 }
 unset($val);
 $array = array_values($array);
};

but it messed up the array, all I get is [0] => null. What is wrong?

Edit: so input data:

$a = [
 'a' => 1,
 'b' => 2,
 'c' => [
 'aa' => 11,
 'bb' => [
 'ccc' => 1
 ],
 'cc' => 33
 ]
];

and I want to have:

array(3) {
 [0]=>
 int(1)
 [1]=>
 int(2)
 [2]=>
 array(3) {
 [0]=>
 int(11)
 [1]=>
 array(1) {
 [0]=>
 int(1)
 }
 [2]=>
 int(33)
 }
}

• Narendrasingh Sisodia: Can you post some input along with expected output

Answer 1

If memory is an issue you can try using yield. I'm not sure if this fits your needs, but here it is:

function reduce($array){
 foreach($array as $key => $value){
 if(is_array($value)){
 reduce($value);
 }
 }
 yield array_values($array);
}

---

You can also use send if you need to apply some logic to the generator.

Answer 2

I found the solution:

$fix_keys = function(array &$array) use (&$fix_keys)
{
 foreach(array_keys($array) as $k)
 {
 if (is_array($array[$k]))
 {
 $fix_keys($array[$k]);
 }
 }
 $array = array_values($array);
};