PHP源代码过滤空行和注释

<?php
$str=file_get_contents('D:\Apache2.2\htdocs\yiqi\web\libs\baseclass\db.class.php');

$str=preg_replace('/\/\*(.*?)\*\//is','',$str);
$str=preg_replace('/\/\/(.*?)\\n/is','',$str);
$str=preg_replace('(\n[\s| ]*\n)',"\n",$str);
echo $str;