如何在PHP中获取数组中的所有字母字符？

$array = array('abc', 'def', 'ghi');
$result = array();

foreach ($array as $item) {
    preg_match_all('/[a-zA-Z]/', $item, $matches);
    $result[] = implode('', $matches[0]);
}

print_r($result);

$array = array('abc', 'def', 'ghi');
$result = array();

foreach ($array as $item) {
    $result[] = implode('', array_filter(str_split($item), function($val) {
        return ctype_alpha($val);
    }));
}

print_r($result);