Online PHP editor | output for NCapg

<?php function position($s) { $unique_domains = [ 'www.crownworldwide.com', 'www.acquisition.gov', 'www.hemisphere-freight.com', 'www.businessinsider.com', 'www.oceansidelogistics.com', 'mixjet.aero', 'www.airindiaexpress.in', 'rlglobal.com', 'www.metroshipping.co.uk', 'www.flexport.com' ]; return array_keys(array_filter($unique_domains, function($elm) use ($s){ if (preg_match('/'.$s.'/', $elm)) { return true; } return false; }))[0] ?? null; } print_r(position('flexport.com')); // 9 echo '<br/>'; print_r(position('www.flexport.com')); // 9 echo '<br/>'; print_r(position('.com')); // 0