Generate Random ID in PHP with no zeros, o's, ones's, or L's

I would like to create a random ID like an airline ticket with out any zeros, o's, ones's, or L's. It would be nice i开发者_如何学运维f server time was used in the generation process so no two IDs will be the same. How would one do this?

Following the awesome PHP naming scheme:

function generate_airline_ticket_number($length) {
  $characters = '23456789abcdefghjkmnpqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ';
  $max = strlen($characters) - 1;
  $string = '';

  for ($i = 0; $i < $length; $i++) {
    $string .= $characters[mt_rand(0, $max)];
  }

  return $string;
}

I should submit this to be included into PHP6 ;)

If you're worried about collisions, my approach would be to do an endless loop:

do
{
  $random_stuff = generate_airline_ticket_number(10);
} while(check_if_string__is_not_in__the_database($random_stuff));

There is always possibility that generated number will be repeated.

You have to store that generated earlier numbers and always check if currently generated number does not exist.

To generate a random number you can just use int rand ( int $min , int $max )

uniqid() seems perfect, apart from your limitations on letters and numbers. Selecting a great font may mitigate some of your needs, so you have L, a zero with a strike through, etc.

Baring that, you haven't placed any other limitations so what about.

$id  = uniqid()
$bad = array("0", "o", "l", "1");
$good = array("-", "#", "&", "$");

$id_clean = str_replace($bad, $good, $id);

The power of uniqid() combined with easily identified characters.

Another option

function genGoodRandString() {
    $rnd_id = md5(uniqid(rand(), true)); // get long random id
    $bad = array('0','o','1','l','8'); // define bad chars
    $fixed = str_replace($bad, '', $rnd_id); // fix
    return substr($fixed, 0, 10); // cut to required length
}

Why not just use a hash like MD5? I believe PHP has a md5() function built in. Another good one to use is sha1().

Using both of these hash functions you will end up getting what you don't want so I suggest you run a regex pattern on the hash to replace them with a random letter A-Z.

Oh, and hashes are usually 100% unique.

I guess I learned something new today.