PHP-生成自定义长度随机字符串方法

$length 生成字符串长度
function createNoncestr($length = 32)
{
    $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
    $str = '';
    for ($i = 0; $i < $length; $i++) {
        $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
    }
    return $str;
}