请大家帮小弟我看看这个截取网址的正则有关问题在哪？感谢

<?php<br /><br /><br />$strtest1 = 'e7342287f1485896249c474049d5317c:1:0:<br><font color='#FF8000'>------解决思路----------------------</font><br>http://img01.taobaocdn.com/bao/uploaded/i1/T1dNrmFEJaXXXXXXXX_!!0-item_pic.jpg;78e4591d5b18775a71912801623c0d26:1:1:<br><font color='#FF8000'>------解决思路----------------------</font><br>http://img01.taobaocdn.com/bao/uploaded/i1/1643666761/TB2aMrfaFXXXXbGXpXXXXXXXXXX_!!1643666761.jpg;';<br /><br />$strtest2 = '<a href="http://www.williamlong.info/cat/?tags=Programming" :<br><font color='#FF8000'>------解决思路----------------------</font><br>rel="tag"><img  src="17c:1:0:<br alt="请大家帮小弟我看看这个截取网址的正则有关问题在哪？感谢" ><font color='#FF8000'>------解决思路----------------------</font><br>http://img01.taobaocdn.com/bao/uploaded/i1/T1dNrmFEJaXXXXXXXX_!!0-item_pic.jpg" alt="研发" class="thumb" /></a>';<br /><br />$regstr = '/http:\/\/img.*(?:\.jpg<br><font color='#FF8000'>------解决思路----------------------</font><br>\.png<br><font color='#FF8000'>------解决思路----------------------</font><br>\.gif)/U';<br /><br />preg_match_all($regstr, $strtest1, $match);<br /><br />var_dump($match);<br /><br />preg_match_all($regstr, $strtest2, $match);<br /><br />var_dump($match);<br /><br /><br />?>