Question

I have a small piece of code that checks a string for a url and adds the < a href> tag to create a link. I also have it check the string for a youtube link and then add rel=”youtube” to the < a> tag.

How can I get the code to only add rel to the youtube links?

How can I get it to add a different rel to any type of image link?

$text = "http://site.com a site www.anothersite.com/ http://www.youtube.com/watch?v=UyxqmghxS6M here is another site";

$linkstring = preg_replace( '/(http|ftp)+(s)?:(\/\/)((\w|\.)+)(\/)?(\S+)?/i', '<a href="\0">\4</a>', $text ); 
if(preg_match('/http:\/\/www\.youtube\.com\/watch\?v=[^&]+/', $linkstring, $vresult)) {
    $linkstring = preg_replace( '/(http|ftp)+(s)?:(\/\/)((\w|\.)+)(\/)?(\S+)?/i', '<a rel="youtube" href="\0">\4</a>', $text ); 
          $type= 'youtube';
          }
else {
$type = 'none';
}
echo $text;
echo $linkstring, "<br />";
echo $type, "<br />";

Answer 1

Try http://simplehtmldom.sourceforge.net/.

Code:

<?php
include('simple_html_dom.php');

$html = str_get_html('<a href="http://www.youtube.com/watch?v=UyxqmghxS6M">Link</a>');
$html->find('a', 0)->rel = 'youtube';
echo $html;

Output:

[username@localhost dom]$ php dom.php
<a href="http://www.youtube.com/watch?v=UyxqmghxS6M" rel="youtube">Link</a>

You can build an entire page DOM or a simple single link with this library.

Detecting hostname of URL:
Pass the url to parse_url. parse_url returns an array of the URL parts.

Code:

print_r(parse_url('http://www.youtube.com/watch?v=UyxqmghxS6M'));

Output:

Array
(
    [scheme] => http
    [host] => www.youtube.com
    [path] => /watch
    [query] => v=UyxqmghxS6M
)