正则如此匹配重复字符串？

Question

 afasdf<img src="images/bar/bar_07.jpg" />adfdsaf<img src="images/bar/bar_07.jpg" />afdadsf<img src="images/bar/bar_07.jpg" />afddsafdasf<img src="images/bar/bar_07.jpg" />

Answer 1

$s =<<< TXT
afasdf<img src="images/bar/bar_07.jpg" />adfdsaf<img src="images/bar/bar_07.jpg" />afdadsf<img src="images/bar/bar_07.jpg" />afddsafdasf<img src="images/bar/bar_07.jpg" />
TXT;preg_match_all('/.*(<.+).*\\1.*\\1.*/', $s, $r);
print_r($r[1]);
Array
(
    [0] => <img src="images/bar/bar_07.jpg" />
)