Find all matches between delimeters

Question

How do I replace all <p> tags between delimiters? My text is

<p>other text...</p>
<p>other text...</p>
``text text...</p>
<p>text text...</p>
<p>text text ...``
<p>other text...</p>
<p>other text...</p>
``text text...</p>
<p>text text...</p>
<p>text text ...``
<p>other text...</p>
<p>other text...</p>
``text text...</p>
<p>text text...</p>
<p>text text ...``
<p>other text...</p>
<p>other text...</p>

I want to match all <p> tags between double backticks (``all p tags here``) as delimiters and replace them with empty string. I could match p tags if there is no other text outside delimiters using regex /<\/?p>/i but how can I match all p tags inside delimiters if there is text and other p tags outside them.

Answer 1

This is a job for preg_replace_callback:

$str = <<<EOD
<p>other text...</p>
<p>other text...</p>
``text text...</p>
<p>text text...</p>
<p>text text ...``
<p>other text...</p>
<p>other text...</p>
``text text...</p>
<p>text text...</p>
<p>text text ...``
<p>other text...</p>
<p>other text...</p>
``text text...</p>
<p>text text...</p>
<p>text text ...``
<p>other text...</p>
<p>other text...</p>
EOD;

$res = preg_replace_callback(
        '/``(?:(?!``).)*``/s', 
        function ($m) {
            return preg_replace('~</?p>~', '', $m[0]);
        },
        $str);
echo $res;

Output:

<p>other text...</p>
<p>other text...</p>
``text text...
text text...
text text ...``
<p>other text...</p>
<p>other text...</p>
``text text...
text text...
text text ...``
<p>other text...</p>
<p>other text...</p>
``text text...
text text...
text text ...``
<p>other text...</p>
<p>other text...</p>