关于正则,该如何解决

关于正则
<!--123-->如何用正则去掉注释<!---->.保留123.谢谢~

[解决办法]

PHP code

[User:root Time:17:23:03 Path:/home/liangdong/php]$ php preg.php 123456[User:root Time:17:23:04 Path:/home/liangdong/php]$ cat preg.php <?php$str = '9kdasf<!--123-->d8asdkM\n<!--456-->addf';$nmatches = preg_match_all('/<!--(.*)-->/Uis', $str, $matches);if ($nmatches) {        foreach ($matches[1] as $content) {                echo $content . PHP_EOL;        }}?>
[解决办法]
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PHP code
[User:root Time:17:23:03 Path:/home/liangdong/php]$ php preg.php 
123
456
[User:root Time:17:23:04 Path:/home/liangdong/php]$ cat preg.php 
<?php
$str = '9kdasf<!--123-->d8asdkM\n<!--456-->……