PHP -按大写和小写字母拆分数组

<?php
function splitArrayByCase($array) {
    $lowercaseArray = array();
    $uppercaseArray = array();

    foreach ($array as $element) {
        if (ctype_lower($element)) {
            $lowercaseArray[] = $element;
        } else {
            $uppercaseArray[] = $element;
        }
    }

    return array(
        'lowercase' => $lowercaseArray,
        'uppercase' => $uppercaseArray
    );
}

$array = array('Apple', 'banana', 'Cherry', 'date', 'Elderberry');
$result = splitArrayByCase($array);

echo "Lowercase Array: ";
print_r($result['lowercase']);

echo "Uppercase Array: ";
print_r($result['uppercase']);
?>

Lowercase Array: Array
(
    [0] => banana
    [1] => date
)

Uppercase Array: Array
(
    [0] => Apple
    [1] => Cherry
    [2] => Elderberry
)