preg_match on dynamic url - php

Question

Is there a way in php to do a preg_match on a url like below
dynamic/dynamic/dev/new_mobile/lib
and it would only pull out dev/new_mobile, and the link also has the ability to be like this too
dynamic/dynamic/dynamic/tst/new_mobile/lib
In the above example it would only pull out tst/new_mobile. The key is it would grab the last two directories before lib. Any idea how this could be done?

Answer 1

Here's a regex that will get the part you want:
$url = 'dynamic/tst/new_mobile/lib/foo/bar';
if (preg_match('#^(?:.*?/)?([^/]+/[^/]+)/lib(?:/.+)?$#', $url, $matches)) {
$part = $matches[1];
var_dump($part); // "tst/new_mobile"
}
This will get the 2 directories before the lib directory allowing for any directories before and after. It will also match a couple of edge cases that you don't mention whether you need:
tst/new_mobile/lib/foo/bar
/tst/new_mobile/lib/foo/bar

Answer 2

just explode then reverse array, simple and easy to use.
$array_url = explode('/',$url);
$tmp_array_url = array_reverse($array_url);
then you can rebuild as you will, no need to wonder with how many dynamic parts come before.
echo $tmp_array_url[0]; // "lib";
echo $tmp_array_url[1]; // "new_mobile";
echo $tmp_array_url[2]; // "dev";
EDIT: since you got lib constant, just do something like this :
$the_two_before = "";
for($i = 0; $i < count($tmp_array_url); $i++){
if($tmp_array_url[$i] == "lib"){
$the_two_before = $tmp_array_url[$i+2]."/".$tmp_array_url[$i+1];
}
}