Problem with PHP preg_match_all

Posted on 2009-04-10
Last Modified: 2012-05-06
I'm tryign to crap a web site but I think an ascii character code is messing it up.

Everythign works fine untill I try to get the title of a video..   I load the page into $html, in the beginnign section of my script, I need to get the video code so I have already set the $item.

The complete line in the html is "<h1><a href="/watch/265126/come-on-in-im-home-pt-13/"> come on in, i&#39;m home,  pt 1/3</a></h1>"   I want to extract the title of the video between ""<h1><a href="/watch/265126/come-on-in-im-home-pt-13/">" and "</a></h1>"

The problem is, I could extract the title as is, but the html is always changing, my variable $item will always be updated with the nex code's need.  I think the &#39; is giving me a problem on that one video which breaks my script.

$item = "<h1><a href="/watch/265126/come-on-in-im-home-pt-13/">";
preg_match_all("/".$item."(.+?)\<\/a><\/h1>/is", $html, $match );
Debug Warning: D:\www\youtube1.php line 125 - preg_match_all() [<a href='function.preg-match-all'>function.preg-match-all</a>]: Unknown modifier 'w'

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Question by:megarry
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LVL 18

Expert Comment

ID: 24115801
The problem that is generating the error has to do with the fact that there are /s in $item that are not escaped. You are using the / as a delimiter and preg_match all is seeing the / in "/watch/265126/come" as the closing delimiter and this is why it says "Unknown modifier 'w'"

try the following (note that I removed your escaping of /s and changed the delimiter to a #

$item = '<h1><a href="/watch/265126/come-on-in-im-home-pt-13/">';
preg_match_all("#".$item."(.+?)\</a></h1>#is", $html, $match );

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LVL 18

Expert Comment

ID: 24115821
another minor change, the < should not need to be escaped

$item = "<h1><a href="/watch/265126/come-on-in-im-home-pt-13/">";
preg_match_all("/".$item."(.+?)<\/a><\/h1>/is", $html, $match );

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LVL 18

Accepted Solution

Hube02 earned 500 total points
ID: 24115828
Sorry, coppied the wrong code

$item = '<h1><a href="/watch/265126/come-on-in-im-home-pt-13/">';
preg_match_all("#".$item."(.+?)</a></h1>#is", $html, $match );

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Author Comment

ID: 24115831
I never knew you can use a delimiter of your choosing..  Always though you needed the "/ and /"..  Thanks! That will help not only with this problem but moving ahead!  

Works perfectly now..  :)
LVL 18

Expert Comment

ID: 24116188
You can also use sets of characters, for instance < and > or [ and ], though I don't generally use these. I like to use the # when dealing with html because this character usually does not appear in the regular expression.

They don't really cover this very well in what I've found of online documentation.

An excellent resource for anyone interested in regular expressions is Mastering Regular Expressions by Jeffrey Friedl

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