Let's assume I do preg_replace as follows:
preg_replace ("/<my_tag>(.*)<\/my_tag>/U", "<my_new_tag>$1</my_new_tag>", $sourse);
That works but I do also want to grab the attribute of the my_tag - how would I do it with this:
<my_tag my_attribute_that_know_the_name_of="some_value">tra-la-la</my_tag>
You don't use regex. You use a real parser, because this stuff cannot be parsed with regular expressions. You'll never know if you've got all the corner cases quite right and then your regex has turned into a giant bloated monster and you'll wish you'd just taken fredley's advice and used a real parser.
For a humourous take, see this famous post.
preg_replace('#<my_tag\b([^>]*)>(.*?)</my_tag>#',
'<my_new_tag$1>$2</my_new_tag>', $source)
The ([^>]*) captures anything after the tag name and before the closing >. Of course, > is legal inside HTML attribute values, so watch out for that (but I've never seen it in the wild). The \b prevents matches of tag names that happen to start with my_tag, preventing bogus matches like this:
<my_tag_xyz>ooga-booga</my_tag_xyz><my_tag>tra-la-la</my_tag>
But that will still break on <my_tag> elements wrapped in other <my_tag> elements, yielding results like this:
<my_tag><my_tag>tra-la-la</my_tag>
If you know you'll never need to match tags with other tags inside them, you can replace the (.*?) with ([^<>]++).
I get pretty tired of the glib "don't do that" answers too, but as you can see, there are good reasons behind them--I could come up with this many more without having to consult any references. When you ask "How do I do this?" with no background or qualification, we have no idea how much of this you already know.
Forget regex's, use this instead:
http://simplehtmldom.sourceforge.net/
Related
I've got a database with a lot of user made entries grown about 10 years. The users had the option to put HTML-code in their content. And some didn't that well. So I've a lot of content in where the quotes are missing. Need a valid HTML-code for an ex/import via XML.
Had tested to replace width but my regex doesn't work. Do you've an idea where's my fault?
$out=preg_replace("/<a href=h(.)*>/","<a href=\"h$1\">",$out);
PS: If you have an idea how to automatically make a correction on wrong html source this would alternatively be great.
I think you wanted to use "/<a href=h(.*)>/" (mind the star inside the parenthesis) since you want to capture all characters after the h and before the > inside the capture group.
You can also use <a href=([^"].*)> since the href may not start with h. This regex captures all href values that do not start with ".
Yet, all of these assume that the href is the last attribute in your a, i.e.., ending with >.
As a more general rule, I came up with (?<key>\w*)\s*=\s*(?<value>[^"][^\s>]*) that finds attribute-value pairs, separated by =. The values may not start with ", and they go until the next whitespace or >. Use this with caution, since it may fail in serveral circumstances: Multi-line html, inline JavaScript, etc.
Whether it is a good idea to use RegEx for such a task is a different discussion.
I need to match all three types of comments that PHP might have:
# Single line comment
// Single line comment
/* Multi-line comments */
/**
* And all of its possible variations
*/
Something I should mention: I am doing this in order to be able to recognize if a PHP closing tag (?>) is inside a comment or not. If it is then ignore it, and if not then make it count as one. This is going to be used inside an XML document in order to improve Sublime Text's recognition of the closing tag (because it's driving me nuts!). I tried to achieve this a couple of hours, but I wasn't able. How can I translate for it to work with XML?
So if you could also include the if-then-else login I would really appreciate it. BTW, I really need it to be in pure regular expression expression, no language features or anything. :)
Like Eicon reminded me, I need all of them to be able to match at the start of the line, or at the end of a piece of code, so I also need the following with all of them:
<?php
echo 'something'; # this is a comment
?>
Parsing a programming language seems too much for regexes to do. You should probably look for a PHP parser.
But these would be the regexes you are looking for. I assume for all of them that you use the DOTALL or SINGLELINE option (although the first two would work without it as well):
~#[^\r\n]*~
~//[^\r\n]*~
~/\*.*?\*/~s
Note that any of these will cause problems, if the comment-delimiting characters appear in a string or somewhere else, where they do not actually open a comment.
You can also combine all of these into one regex:
~(?:#|//)[^\r\n]*|/\*.*?\*/~s
If you use some tool or language that does not require delimiters (like Java or C#), remove those ~. In this case you will also have to apply the DOTALL option differently. But without knowing where you are going to use this, I cannot tell you how.
If you cannot/do not want to set the DOTALL option, this would be equivalent (I also left out the delimiters to give an example):
(?:#|//)[^\r\n]*|/\*[\s\S]*?\*/
See here for a working demo.
Now if you also want to capture the contents of the comments in a group, then you could do this
(?|(?:#|//)([^\r\n]*)|/\*([\s\S]*?)\*/)
Regardless of the type of comment, the comments content (without the syntax delimiters) will be found in capture 1.
Another working demo.
Single-line comments
singleLineComment = /'[^']*'|"[^"]*"|((?:#|\/\/).*$)/gm
With this regex you have to replace (or remove) everything that was captured by ((?:#|\/\/).*$). This regex will ignore contents of strings that would look like comments (e.g. $x = "You are the #1"; or $y = "You can start comments with // or # in PHP, but I'm a code string";)
Multiline comments
multilineComment = /^\s*\/\*\*?[^!][.\s\t\S\n\r]*?\*\//gm
I'm stuck with php preg_match_all function. Maybe someone wil help me with regexp. Let's assume we have some code:
[a]a[/a]
[s]a[/s]
[b]1[/b]
[b]2[/b]
...
...
[b]n[/b]
[e]a[/e]
[b]8[/b]
[b]9[/b]
...
...
[b]n[/b]
I need to match all that inside [b] tags located between [s] and [e] tags. Any ideas?
if your structure is exactly the same as above I would personally avoid regex (not a good idea with these fort of languages) and just check the second char of each line. Once you see an s go into consume mode and for each line until you see an e find the first ] and read in everything between that and the next [
For simplicity use two preg_match calls.
First to retrieve the list you want to inspect /\[s](.+?)\[e]/s.
And then use that result string and match for the contained /\[b](.+?)\[\/b]/s things.
It looks like you are trying to pattern match something that has a treelike structure, essentially like HTML or XML. Any time you find yourself saying "find X located inside matching Y tags" you are going to have this problem.
Trying to do this sort of work with with regular expressions is a Bad Idea.
Here's some info copy/pasted from a different answer of mine for a similar question:
Some references to similar SO posts which will give you an idea of the difficulty you're getting into:
Regex to match all HTML tags except <p> and </p>
Regex to replace all \n in a String, but no those inside [code] [/code] tag
RegEx match open tags except XHTML self-contained tags - bobince says it much more thoroughly than I do (:
The "Right Thing" to do is to parse your input, maintaining state as you go. This can be as simple as scanning your text and keeping a stack of current tags.
Regular expressions alone aren't sufficient to parse XML, and this appears to be a simplified XML language here.
I am attempting to match a string which is composed of HTML. Basically it is an image gallery so there is a lot of similarity in the string. There are a lot of <dl> tags in the string, but I am looking to match the last <dl>(.?)+</dl> combo that comes before a </div>.
The way I've devised to do this is to make sure that there aren't any <dl's inside the <dl></dl> combo I'm matching. I don't care what else is there, including other tags and line breaks.
I decided I had to do it with regular expressions because I can't predict how long this substring will be or anything that's inside it.
Here is my current regex that only returns me an array with two NULL indicies:
preg_match_all('/<dl((?!<dl).)+<\/dl>(?=<\/div>)/', $foo, $bar)
As you can see I use negative lookahead to try and see if there is another <dl> within this one. I've also tried negative lookbehind here with the same results. I've also tried using +? instead of just + to no avail. Keep in mind that there's no pattern <dl><dl></dl> or anything, but that my regex is either matching the first <dl> and the last </dl> or nothing at all.
Now I realize . won't match line breaks but I've tried anything I could imagine there and it still either provides me with the NULL indicies or nearly the whole string (from the very first occurance of <dl to </dl></div>, which includes several other occurances of <dl>, exactly what I didn't want). I honestly don't know what I'm doing incorrectly.
Thanks for your help! I've spent over an hour just trying to straighten out this one problem and it's about driven me to pulling my hair out.
Don't use regular expressions for irregular languages like HTML. Use a parser instead. It will save you a lot of time and pain.
I would suggest to use tidy instead. You can easily extra all the desired tags with their contents, even for broken HTML.
In general I would not recommend to write a parser using regex.
See http://www.php.net/tidy
As crazy as it is, about 2 minutes after I posted this question, I found a way that worked.
preg_match_all('/<dl([^\z](?!<dl))+?<\/dl>(?=<\/div>)/', $foo, $bar);
The [^\z] craziness is just a way I used to say "match all characters, even line breaks"
I'm trying to put together a plug-in for vBulletin to filter out links to filesharing sites. But, as I'm sure you often hear, I'm a newb to php let alone regexes.
Basically, I'm trying to put together a regex and use a preg_replace to find any urls that are from these domains and replace the entire link with a message that they aren't allowed. I'd want it to find the link whether it's hyperlinked, posted as plain text, or enclosed in [CODE] bb tags.
As for regex, I would need it to find URLS with the following, I think:
Starts with http or an anchor tag. I believe that the URLS in [CODE] tags could be processed the same as the plain text URLS and it's fine if the replacement ends up inside the [CODE] tag afterward.
Could contain any number of any characters before the domain/word
Has the domain somewhere in the middle
Could contain any number of any characters after the domain
Ends with a number of extentions such as (html|htm|rar|zip|001) or in a closing anchor tag.
I have a feeling that it's numbers 2 and 4 that are tripping me up (if not much more). I found a similar question on here and tried to pick apart the code a bit (even though I didn't really understand it). I now have this which I thought might work, but it doesn't:
<?php
$filterthese = array('domain1', 'domain2', 'domain3');
$replacement = 'LINKS HAVE BEEN FILTERED MESSAGE';
$regex = array('!^http+([a-z0-9-]+\.)*$filterthese+([a-z0-9-]+\.)*(html|htm|rar|zip|001)$!',
'!^<a+([a-z0-9-]+\.)*$filterthese+([a-z0-9-]+\.)*</a>$!');
$this->post['message'] = preg_replace($regex, $replacement, $this->post['message']);
?>
I have a feeling that I'm way off base here, and I admit that I don't fully understand php let alone regexes. I'm open to any suggestions on how to do this better, how to just make it work, or links to RTM (though I've read up a bit and I'm going to continue).
Thanks.
You can use parse_url on the URLs and look into the hashmap it returns. That allows you to filter for domains or even finer-grained control.
I think you can avoid the overhead of this in using the filter_var built-in function.
You may use this feature since PHP 5.2.0.
$good_url = filter_var( filter_var( $raw_url, FILTER_SANITIZE_URL), FILTER_VALIDATE_URL);
Hmm, my first guess: You put $filterthese directly inside a single-quoted string. That single quotes don't allow for variable substitution. Also, the $filterthese is an array, that should first be joined:
var $filterthese = implode("|", $filterthese);
Maybe I'm way off, because I don't know anything about vBulletin plugins and their embedded magic, but that points seem worth a check to me.
Edit: OK, on re-checking your provided source, I think the regexp line should read like this:
$regex = '!(?#
possible "a" tag [start]: )(<a[^>]+href=["\']?)?(?#
offending link: )https?://(?#
possible subdomains: )(([a-z0-9-]+\.)*\.)?(?#
domains to block: )('.implode("|", $filterthese).')(?#
possible path: )(/[^ "\'>]*)?(?#
possible "a" tag [end]: )(["\']?[^>]*>)?!';