function num2alpha($number) {
    $result = '';
    while ($number > 0) {
        $number--; // Adjust for 0-indexing
        $result = chr($number % 26 + 65) . $result; // Convert to letter
        $number = intval($number / 26); // Move to the next "digit"
    }
    return $result;
}

不能传入0,要从1开始才行

破罐子互摔