Move chunk of HTML with RegEx - html

Question

What I am trying to do is find a chunk of HTML that has comments chunk!--/block--> and move it in its entirety right after header. The thing is that the comment always remains the same but the chunk varies through pages using find and replace in Dreamweaver. Here is a quick sample:
<!--header-->
<header>Hello</header>
<!--/header-->
This is where the chunk needs to be moved
<h1>Hello content</h1>
<p>lorem ipsum</p>
This is the chunk, it has a starting comment and ending one, I thought it might be used as a references for RegEx including everything inside.
<!--block-->
<p>hello world</p>
<!--/block-->

Answer 1

Ok. You didn't specify the language for reular expression but this PHP code does what you need I just wrote it and tested it. As a bonus I wrote the final result back to the source page.
First you have your original file, I called mine source.php
<!--header--> <header>SO HERE IS THE HEADER</header> <!--/header-->
<div>this is information that is above ID CARR, but will be below the div ID carr once php is done executing..</div>
<div id="carr"> Phasellus laoreet dolor magna, et tempor mi dictum eu. Aenean pellentesque vulputate tortor. Vestibulum odio velit, faucibus sed dui non, laoreet facilisis sem. Curabitur a magna ligula. Cras cursus vel dui placerat posuere. Donec ullamcorper risus eu lobortis dignissim. Nullam fermentum est diam, sed lacinia sapien ornare et. </div> <div>here is more informatin on the bottom</div>
Then you have another page called index.php that does what you want. In this example I am targeting the above.
<?php
$page_path = 'source.php';
$source = file_get_contents($page_path);
$regex = '#\<div id="carr">(.+?)\</div>#s';
preg_match($regex, $source, $matches);
$match = $matches[0];
$a = explode("</header>", $source);
//strip out what we found with regular expression
$first = str_replace($match, '', $source);
//append it to the place where you need it.
$final = str_replace('<!--/header-->', '<!--/header-->'.$match, $first);
echo $final;
$fp = fopen($page_path, 'w+');//w+ erases r+ point at begining of file.
fwrite($fp, $final);
fclose($fp);
?>