How to count string length of a domain list and group them by length?

Question

I have a list of domain names, for example:

domain1.com
domain2.com
domainxxx2.com
dom.com

from that list I want to get:

length 7 [2]
length 10 [1]
length 3 [1]

I know how to split the tld and count each domain length, but dont know how to group and count those with the same length.

I would like to do it on PHP.

Answer 1

Quick and dirty and untested:

$lengths = [];
for ($i = 1; $i <= 255; $i++) {
    foreach ($domains as $domain) {
        if (strlen($domain) === $i) {
            $lengths[$i][] = $domain;
        }
    }
}

Answer 2

Quicker & cleaner but still untested

$sorted = array();
foreach($domains as $domain)
{
    $sorted[strlen($domain)][] = $domain;
}