Regular expression _php techniques that can filter multiple lines of code in DEDECMS collection

In the past with Dede collection, always filtered more than one line of code, can only line of filtering, online, found that there are many and I like the rookie. With the continuous use of Dede acquisition, there is a further understanding of the positive, now I use a regular expression, can also match multiple lines of code.

For example: In the following code, filter out a hyperlink with two lines of code.

<TD align= "center" >
<a href= "http://www.XXX.com/111111.htm" >xxx
Xxx</a>
</td>

With the following filter, you can achieve multiple line matching
{Dede:trim} <a href= "http://www.XXX.com/111111.htm" > ([^\n<]*) </a> {/dede:trim}

Looks like \ n Such a symbol, can act as a newline character, one \ n represents a newline.
Hope to be useful to the beginner Dede.