Flatten Multi-dimensional PHP Array

function flattenArray(array $array) {
    $result = [];
    foreach ($array as $element) {
        if (is_array($element)) {
            $result = array_merge($result, flattenArray($element));
        } else {
            $result[] = $element;
        }
    }
    return $result;
}

$nestedArray = [1, [2, 3], 4, [5, [6, 7]], 8];
$flatArray = flattenArray($nestedArray);

print_r($flatArray);

How it works: This recursive function, `flattenArray`, takes a multi-dimensional array and converts it into a single-dimensional array. It iterates through each element: if an element is an array itself, it recursively calls `flattenArray` on it and merges the result; otherwise, it adds the element directly to the result array. This is a robust way to handle arbitrarily deep nested arrays.