PHP 生成随机字符串

function random($length = 8)
{     
    $chars = 'bcdfghjklmnprstvwxzaeiou';

    for ($p = 0; $p < $length; $p++)
    {
        $result .= ($p%2) ? $chars[mt_rand(19, 23)] : $chars[mt_rand(0, 18)];
    }

    return $result;
}

function random_str($length, $keyspace = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ')
{
    $str = '';
    $max = mb_strlen($keyspace, '8bit') - 1;
    for ($i = 0; $i < $length; ++$i) {
        $str .= $keyspace[random_int(0, $max)];
    }
    return $str;
}