Using a regex variable from within the regex itself, within PHP

Question

My goal: I'm trying to use regex to retrieve a name string from the jumbled response of a file_get_contents() call within PHP.

Here's an excerpt of what I get back from a file_get_contents call, and the string I will be working with:

file_get_contents('http://releases.ubuntu.com/13.10/ubuntu-13.10-desktop-amd64.iso.torrent');

28:announce39://torrent.ubuntu.com:6969/announce13:announce-listll39://torrent.ubuntu.com:6969/announceel44://ipv6.torrent.ubuntu.com:6969/announceee7:comment29:Ubuntu CD releases.ubuntu.com13:creation datei1382003607e4:infod6:lengthi925892608e4:name30:ubuntu-13.10-desktop-amd64.iso12:piece lengthi524288e6:pieces35320:I½ÊŒÞJÕ`9

You can see how I've emboldened the text of interest above. The regex I'm using is currently as follows:

preg_match('/name[0-9]+\:(.*?)\:/i', $c, $matches);

This gives me:

name30:ubuntu-13.10-desktop-amd64.iso12

Now, name30 is the name and also 30 characters in length from the next semi-colon, so how can I use this variable to continue on for only 30 characters length before finishing the regex, whilst removing the "name" string and count characters?

My end goal would be:

ubuntu-13.10-desktop-amd64.iso

Note: I did think of just removing any end numbers instead of character counting, however the filename may not have a valid extension and may just end with numbers in the future.

Explosion Pills · Accepted Answer · 2013-11-26 15:46:32Z

3

Assuming that name([0-9]+): is solid for finding the start of what you need, you could use preg_replace_callback

$names = array();
preg_replace_callback("/name([0-9]+):(.*?):/i", function($matches) use (&$names){
    // Substring of second group up to the length of the first group
    $names[] = substr($matches[2], 0, $matches[1]);
}, $c);

edited Nov 26, 2013 at 15:46

answered Nov 26, 2013 at 15:20

Explosion Pills

192k56 gold badges341 silver badges417 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Jimbo Over a year ago

Nice! No idea who downvoted... Only addition here is to pass $names by reference to make it work (&$names), but that seems to work perfectly, thank you!

Casimir et Hippolyte · Accepted Answer · 2013-11-26 15:41:25Z

2

An other way:

preg_match_all('/:name(\d+):\K[^:]+/', $str, $matches, PREG_SET_ORDER);
foreach ($matches as $match) {
    $results[] = substr(match[0], 0, $match[1]);
}

answered Nov 26, 2013 at 15:41

Casimir et Hippolyte

90k5 gold badges102 silver badges131 bronze badges

Collectives™ on Stack Overflow

Using a regex variable from within the regex itself, within PHP

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related