如何在PHP中转换多维数组

function flattenArray($array) {
    return is_array($array) ? array_map('flattenArray', $array) : $array;
}

$multiDimensionalArray = array(
    array(1, 2, 3),
    array(4, array(5, 6)),
    array(7, 8, 9)
);

$flattenedArray = flattenArray($multiDimensionalArray);
print_r($flattenedArray);

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
    [6] => 7
    [7] => 8
    [8] => 9
)

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, 3),
    array(4, array(5, 6)),
    array(7, 8, 9)
);

$flattenedArray = flattenArray($multiDimensionalArray);
print_r($flattenedArray);

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
    [5] => 6
    [6] => 7
    [7] => 8
    [8] => 9
)