Get potential domain from array of strings

getPotentialDomains.php

<?php 

function getPotentialDomains( $lines ) {
	$re = '~((https|http){1}://(www|ww2|web)?(\.)?(([a-z0-9\-])+\.)+([a-z]{2,}){1})~ui';

	$domains = [];
	foreach ( $lines as $line ) {
		preg_match_all( $re, $line, $matches, PREG_SET_ORDER, 0 );

		$domains = array_merge( $domains, $matches );
	}

	return implode( ',', $domains );
}

echo getPotentialDomains( [
	'https://example.domain/page?=78',
	'http://example.domain/page?=78',
	'["Train (noun)"](https://www.askoxford.com/concise_oed/train?view=uk).',
	'["Train (noun)"](http://aefae.askoxford.com/concise_oed/train?view=uk).'
] );