Question

I have an array in PHP which is multidimensional. It can have any number of levels as it is generated dynamically. None of the arrays contained in the array are empty and all have keys set.

I am looking for a way to get all array keys into a new array. I know how to do it on a single layered array but I am stuck as I don’t know how many levels deep the array will go, it could be a single layered array itself or a 20 level multi dimensional array?

Thanks…

Answer 1

If you want to gather all the keys as the values of a new array, the following should work for you.

// Function to recursively gather keys
function getKeys(&$keyArray, $parentArray) {
    if (!is_array($parentArray) || count($parrentArray) === 0) {
        return;
    }
    foreach ($parentArray as $key => $element) {
        $keyArray[] = $key;
        if (is_array($element)) {
            getKeys($keyArray, $element);
        }
    }
}

// Usage
$arrayToBeChecked = array(array(array(...
$arrayToHoldKeys;
getKeys($arrayToHoldKeys, $arrayToBeChecked);