Generate unique usernames based on given domain names

Question

I want to generate unique usernames based on some string (first 6 letters of domain names).

The problem is that the first 6 letters of domain names, may be the same.

Consider the following table:

Domain        | Username
--------------+------------
a.com         | acom
google.com    | google
yahoo.com     | yahooc
aaaaaa.com    | aaaaaa
aaaaa5.com    | aaaaa5 -- Because `aaaaa5` is still unique
aaaaaab.com   | aaaaa1 -- `aaaaaa` is taken, so we choose `aaaaa` + `1`
aaaaaac.com   | aaaaa2
aaaaaad.com   | aaaaa3
aaaaaae.com   | aaaaa4
aaaaaaf.com   | aaaaa6 -- We had `aaaaa5` before, so we go for `aaaaa6`
.
.
.
aaaaax.com    | aaaa10

I had really no idea where to begin, and didn't find anything after some search.

---

Update: Friends, I'm wondering because of the minuses!

It's nothing strange. Just gonna be like WHMCS's user generation system!

Answer 1

It's not clear how you want to generate the username but this is a way to get a unique one. Hope it gives you an idea where to start:

EDIT:

I edited the code so it generates unique usernames with a maximum of 6 characters. The for loop is just for demonstration purposes.

$basename = 'username';
$usernames = array();
for ($i = 0; $i < 25; $i++) {   
    $username = substr($basename,0,6);
    $number = 0;
    while(in_array($username, $usernames)) {
        $length = strlen($username)-strlen($number);
        $username = substr($basename,0,$length).$number;
        $number++;
    }
    $usernames[] = $username;
    echo $username.'<br>';
}