$re = '/https:+[\w\d-.\/]+jpg/';
$str = '<![CDATA[
<img referrerpolicy="no-referrer" src="https://scontent-sjc3-1.cdninstagram.com/vp/3ae37927158eaae1bb9d4fe0752aa85f/5C1F0F58/t51.2885-15/e35/38261725_382280748969632_602638638102085632_n.jpg"><br>
]]>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php