大侠进！正则表达式小语句～

大侠进！求一个正则表达式小语句～～～
各位大侠～
求教一个正则表达式的提取方法：
下面这个地址

PHP code

<!--

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-->http://www.daikuan.com/sell/show.php?itemid=3">

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PHP code

<!--

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-->preg_match_all('/buy\/show\.php\?itemid=([\'"]?)(\d+)\1(?-i)/', $arrContent[0], $itemidx);

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