Integrate simple invite code script?

[hash1]

Hello, im wanting to create some sort of invite code script where I can generate a handful of active codes and then give them out so that who ever receives them can use them to sign up at my website.

 

Does any one know how I would go about doing this? Im absolutely clueless.

[slurpee]

Something like this?

 

$confCodes = array();
$codeLength = 10;
$numCodes = 100;
for($i=0; $i < $numCodes; $i++) {
  $confCodes[] = substr(md5(rand()),0,$codeLength);
}