Question

Im building my own forum where you can use diffrent types of BBcode and one of them is [youtube][/youtube] to embed youtube videos,

The idea is to make it idiot-proof, the user can enter the full lenght url or just the code to the video like this

[youtube]http://www.youtube.com/watch?v=AJ3_kndmeCg%5B/youtube%5D
[youtube]http://www.youtube.com/watch?v=AJ3_kndmeCg&feature=related%5B/youtube%5D
[youtube]AJ3_kndmeCg[/youtube]

Here is my code that get the code out of a full lenght url,

<?php
$getpost=$_POST['post'];  
$getpost=preg_replace("'\[youtube\].*?=(.*?)&.*?\[/youtube\]'is",'yt link is \\1',$getpost);  
$getpost=preg_replace("'\[youtube\].*?=(.*?)\[/youtube\]'is",'yt link is \\1',$getpost);  
$getpost=preg_replace("'\[youtube\](.*?)\[/youtube\]'is",'yt link is \\1',$getpost);  
?>

The results are:

yt link is AJ3_kndmeCg
yt link is AJ3_kndmeCg
yt link is AJ3_kndmeCg

It works perfectly if I only want to embed 3 youtube videos,

But if i wanted to embed 6 youtube videos like this:

[youtube]http://www.youtube.com/watch?v=AJ3_kndmeCg%5B/youtube%5D
[youtube]http://www.youtube.com/watch?v=AJ3_kndmeCg&feature=related%5B/youtube%5D [youtube]AJ3_kndmeCg[/youtube]
[youtube]http://www.youtube.com/watch?v=AJ3_kndmeCg%5B/youtube%5D
[youtube]http://www.youtube.com/watch?v=AJ3_kndmeCg&feature=related%5B/youtube%5D
[youtube]AJ3_kndmeCg[/youtube]

The results are:

yt link is AJ3_kndmeCg
yt link is AJ3_kndmeCg[/youtube]
yt link is AJ3_kndmeCg
yt link is http://www.youtube.com/watch?v=AJ3_kndmeCg
[youtube]AJ3_kndmeCg

Do you see that^^ the tags still remain on two lines and one of the lines show a full lenght URL,

Answer 1

Wow, this was a real toughie of a regex to write.

Got it for you in one:

$getpost=preg_replace('@\[youtube\].*?(?:v=)?([^?&[]+)(&[^[]*)?\[/youtube\]@is',
             'yt link is \\1', $getpost);

This will work for all the cases you supplied. It will not work if the link begins with a part other than ‘v=’ (for example, ‘http://www.youtube.com/watch?foo=bar&v=AJ3_kndmeCg‘).

Enjoy!