What are the limitations of using PHP string replace within frames or iframes?

When using PHP string replace within frames or iframes, the limitation is that the replacement will only affect the content within that specific frame or iframe. If you want to replace content across multiple frames or iframes, you will need to implement a solution that can target all frames or iframes on the page.

// Get the content of the current page
$content = file_get_contents('http://www.example.com');

// Replace 'old_string' with 'new_string' in the content
$content = str_replace('old_string', 'new_string', $content);

// Output the modified content
echo $content;