21'C 흐림
서울 강남구
<?
$subject = '<iframe width="640" height="360" src="https://www.youtube.com/embed/_3tpMK5-CZk" frameborder="0" allowfullscreen></iframe>';
$pattern ='/(src=|href=)('|")?([^<>s'"]*)('|"|s|)/i';
preg_match_all( $pattern, $subject, $matches );
echo $matches[3][0];
?>