PHP preg_match_all run php function on matched items - php

Question

I'm not sure of the terminology so I apologize ahead of time.
I'm trying to create a PHP template engine that will query a string for <ZONE header> and </ZONE header> and it will pull everything in between and then run a php function to see if the header exists. If the header exists it will display what was in between, and if the header does not exists it will remove what was in between.
Here's an example:
$string = "
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
<ZONE header><img src="images/header.jpg" /></ZONE header>
<p>Nam sollicitudin mattis nisi, eu convallis mi tincidunt vitae.</p>
";
The function would ideally remove <ZONE header><img src="images/header.jpg" /></ZONE header> then it will run the php function I've created header() which checks to see if the "header" exists in the database, and if it does, it will display everything inside <ZONE header></ZONE header> and if it doesn't it will remove it from the string.
If "header" exists:
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
<img src="images/header.jpg" />
<p>Nam sollicitudin mattis nisi, eu convallis mi tincidunt vitae.</p>
If "header" does not exist:
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
<p>Nam sollicitudin mattis nisi, eu convallis mi tincidunt vitae.</p>
Here is what I was working with but got stuck:
preg_match_all("|\<ZONE_header>(.*)\<\/ZONE_header>|isU", $string, $zone, PREG_SET_ORDER);
if (isset($zone) && is_array($zone)) {
foreach ($zone as $key => $zoneArray) {
if ($key == 0) {
$html = $zoneArray[1];
if ($html != "") {
if (header() != "") {
$html = str_replace($zoneArray[0], NULL, $html);
}
}
}
}
}
echo $html;
Any ideas, thoughts, suggestions?
Thank you for any and all help!

Answer 1

Note that I replace your header() function with get_header().
$string = preg_replace_callback('/<ZONE header>(.+)<\/ZONE header>/', 'replace_header', $string);
function replace_header($matches) {
return get_header() ? $matches[1] : '';
}
See documentation for preg_replace_callback.

Answer 2

Like this ?
$string = '
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
<ZONE header><img src="images/header.jpg" /></ZONE header>
<p>Nam sollicitudin mattis nisi, eu convallis mi tincidunt vitae.</p>
';
$pattern="#<ZONE header[^>]*>(.+)</ZONE header>#iU";
preg_match_all($pattern, $string, $matches);
if (strlen($matches[0][0])==0){
$string=strip_tags($string,"<p>");
}
else{
$string=strip_tags($string,"<p><img>");
}
echo $string;