如何在PHP中将多维数组"扁平化"为简单数组？

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

$multiDimensionalArray = array(array(1, 2), array(3, 4), array(array(5, 6), array(7, 8)));
$flattenedArray = flattenArray($multiDimensionalArray);
print_r($flattenedArray);

function flattenArray($array) {
    $result = array();
    $stack = array();
    $stack[] = $array;

    while (!empty($stack)) {
        $current = array_pop($stack);
        foreach ($current as $element) {
            if (is_array($element)) {
                $stack[] = $element;
            } else {
                $result[] = $element;
            }
        }
    }
    return $result;
}

$multiDimensionalArray = array(array(1, 2), array(3, 4), array(array(5, 6), array(7, 8)));
$flattenedArray = flattenArray($multiDimensionalArray);
print_r($flattenedArray);