Question

How to make my id generator code elegant: When a user registers they get an id.. What is the chance that the id generated will NOT be unique? Also – How can i make my code elegant?
THANKS!

#hash = random url generated from 128 chars

$cac = substr($hash, 64,-60);

$words = array('GET', 'COOL', 'WOW', 'YES', 'NICE', 'BUCK', 'LUCK', 'FUN', 'CASH', 'TIP', 'PEEK', 'TAG'); 
$rword = rand(0,11);

$syms = array('-', '#', '$', '@');
$rsym = rand(0,3); 

$nums = rand(0,9);

$aff_id_temp = $words[$rword] . $syms[$rsym] . $cac . $nums;
$final_id = strtoupper($aff_id_temp);

—UPDATE—
The code works. Just need to generate a simple affiliate id for users when they register. By elegant I mean – perhaps the way I am hacking out the final product code be done more simply or in a different way (perhaps in a loop) basically I want to learn different ways to achieve the same result. I want other coding perspectives.

The output is something like: TIP#6C1D2

Answer 1

Practically zero, due to the hash. That said, it depends entirely on the hash function.

Excluding the hash, the chance of any given id colliding with another given id is 1/(12*4*10) = 1/480, roughly 0.2%. However, the chance of a new id not colliding with any other id is 1-(1-1/480)^c, where c is the number of ids you already have. With just 50 ids you already have a 10% chance of collision.

You can get a unique hash with the uniqid function.