I know how to extract web address from url like this:
https://www.youtube.com/watch?v=j__wz7NtNgM
I can extract "youtube.com" from it.
I have no idea how to extract web address from a string like this
my fav website is youtube.com snel ip
How to extract "youtube.com" from it?
you can use different functions.
There are:
preg_match
trim
parse_url
I suggest you using the parse_url function, you can work with it more easy.
To check the url with the preg_match function you have to declare the whole
regex of a url. With the trim function you can split the parts off,
e.g. the http://xxx part or the part behind this section
Even though you’re implementing it in PHP, it’s rather a question of regular expression, right?
Just like a complete URL, you can match the fragment of hostname and TLD from any text. The former’s got the advantage that, to put it a bit bluntly, it starts with https? which can’t be mistaken so easily. On the other hand, it’s hard to tell apart if it’s a web address or if someone just missed hitting space:
my fav website is youtube.com snel ip and it blows.museum is closed, right?
One possible trade-off is by detecting addresses that start with either a protocol or a dubdubdub:
(https?:\/\/([a-z]+\.)*|www\.)([a-z0-9]+\.[a-z]{2,})(\/)?
That’s a bit safer, but it won’t match your example. So, another imperfect way is to detect links if they have some sort of boundary around them:
(^|\b|\s)([a-z0-9]+\.[a-z]{2,})(\b|\W|$)
You could narrow mismatches by making a whitelist of TLDs like (com|net), but I’d not do that; remember there’s IDNs. If you wish to support something like http://موقع.وزارة-الاتصالات.مصر/, it gets a bit more sophisticated.
The regular expressions above do work, though their intent is to be a mere lead to further adjust to your needs and to propose another solution respectively.
Related
I know this question has been asked about a dozen times, but this one is not technically a dupe (check the others if you like) ;)
Basically, I have a Javascript regex that checks email addresses which I use for front-end validation, and I use CodeIgniter to double check on the back end, in case the validation on the front end fails to run properly (browser issues, for instance.) It's QUITE a long regular expression, and I have no idea where to begin converting it by hand.
I'm pretty much looking for a tool that converts JS regexes to PHP regexes - I haven't found one in any of the answers to similar questions (of course, it's possible that such a tool doesn't exist.) Okay, I lied - one of them suggested a tool that costs $39.95, but I really don't want to spend that much to convert a single expression (and no, there isn't a free trial as suggested by the answer to the aforementioned question.)
Here's the Javascript expression, graciously provided by aSeptik:
/^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))#((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/i
And the one used by CodeIgniter, which I don't want to use because it doesn't follow the same rules (disallows some valid addresses):
/^([a-z0-9\+_\-]+)(\.[a-z0-9\+_\-]+)*#([a-z0-9\-]+\.)+[a-z]{2,6}$/ix
I want to use the same rules set by the Javascript regex in PHP.
Having this sort of inconsistency where my front-end code is saying that the email address is okay, and then Codeigniter says it isn't, is of course the behavior I'm trying to fix in my application.
Thanks for any and all tips! :D
There are some differences between regex engines in Javascript and PHP. Please check Comparison of regular-expression engines
article for theoretical and Difference between PHP regex and JavaScript regex answer for practical information.
Most of the time, you can use Javascript regex patterns in PHP with small modifications. As a fundamental difference, PHP regex is defined as a string (or in a string) like this:
preg_match('/^\(?(\d{3})\)?[- ]?(\d{3})[- ]?(\d{4})$/',$telephone);
Javascript regex is not, it's defined in its own way:
var ptr = new RegExp(/^\(?(\d{3})\)?[- ]?(\d{3})[- ]?(\d{4})$/);
// or
var ptr = /^\(?(\d{3})\)?[- ]?(\d{3})[- ]?(\d{4})$/;
You can give it a try by running the regex on PHP. As a recommendation, do not replace it in Codeigniter files, you can simply extend or replace native library. You can check Creating Libraries out for more information.
I was able to solve this in a better-than-expected manner. I was unable to convert the Javascript regex that I wanted to use (even after purchasing RegexBuddy - it'll come in handy, but it was not able to produce a proper conversion), so I decided to go looking on the Regex Validate Email Address site to see if they had any recommendations anywhere for good regexes. That's when I found this:
"The expression with the best score is currently the one used by PHP's filter_var()":
/^(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){255,})(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){65,}#)(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22))(?:\.(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22)))*#(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\]))$/iD
It matches with only 4/86 errors, while the Javascript one I was using matches with 8/86 errors, so the PHP one is a little more accurate. So, I extended the CodeIgniter Form_validation library to instead use return filter_var($str, FILTER_VALIDATE_EMAIL);.
...But does it work in Javascript?
var pattern = new RegExp(/^(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){255,})(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){65,}#)(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22))(?:\.(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22)))*#(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\]))$/i);
Zing! Works like a charm! Not only did I get the consistency I was looking for between front and back end validation, but I also got a more accurate regex in the process. Double win!
Thank you to all those who provided suggestions!
Today there is exists the site https://regex101.com/ where you can transform one JS regex to PHP or some another languages.
I have been struggling and testing for the last two hours and simply cannot wrap my head around the whole RegEx-stuff enough in order to find a proper solution to this...
I am trying to redirect a couple of URLs from our old site to the new one due to a recent re-launch.
This is the current state of things / a demo of my RegEx
Essentially it looks like this:
.+(\/es|\/de|\/en)?\/(legal)(.+)?
My problem is that a URL like https://example.com/es/projects/legal-yeah is also being matched, which does make sense looking at the rule but is not what I want to achieve...
How can I perform a test which only matches URLs where there is nothing in between the first part for the language string (de/en/es/empty) and the second part (/legal)?
Thanks so much for sharing your thoughts on this, appreciate it!
By using an end-of-line anchor $ and explicitly adding (\/.*) after legal you can achieve what you need:
.+(\/es|\/de|\/en)?\/(legal)(\/.+)?$
https://regex101.com/r/HsIDkQ/8
This final RegEx-rule matches the URLs like I intended – ignoring any other occurences of the "legal"-string (in this case) which might appear in another URL on some other level and 'fuzzy' enough to include all the language-cases, even without a language-string appearing at all.
Solution
The trick in the end was to force the rule to look for a TLD in front of the other stuff so it would only allow for first-level URLs to be included.
UPDATE: My first solution didn't turn out to work since the redirection engine / plugin only makes use of the URL path, not including the domain (see GitHub issue) and as such I can't match the DOT as needed precessor.
Now the rule is paying attention to the start of the string and not accepting anything other the language string in front of the targeted URL-slug which in turn removes false positives.
Thanks to #Xatenev who pointed me in the right direction!
I know this question has been asked about a dozen times, but this one is not technically a dupe (check the others if you like) ;)
Basically, I have a Javascript regex that checks email addresses which I use for front-end validation, and I use CodeIgniter to double check on the back end, in case the validation on the front end fails to run properly (browser issues, for instance.) It's QUITE a long regular expression, and I have no idea where to begin converting it by hand.
I'm pretty much looking for a tool that converts JS regexes to PHP regexes - I haven't found one in any of the answers to similar questions (of course, it's possible that such a tool doesn't exist.) Okay, I lied - one of them suggested a tool that costs $39.95, but I really don't want to spend that much to convert a single expression (and no, there isn't a free trial as suggested by the answer to the aforementioned question.)
Here's the Javascript expression, graciously provided by aSeptik:
/^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))#((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/i
And the one used by CodeIgniter, which I don't want to use because it doesn't follow the same rules (disallows some valid addresses):
/^([a-z0-9\+_\-]+)(\.[a-z0-9\+_\-]+)*#([a-z0-9\-]+\.)+[a-z]{2,6}$/ix
I want to use the same rules set by the Javascript regex in PHP.
Having this sort of inconsistency where my front-end code is saying that the email address is okay, and then Codeigniter says it isn't, is of course the behavior I'm trying to fix in my application.
Thanks for any and all tips! :D
There are some differences between regex engines in Javascript and PHP. Please check Comparison of regular-expression engines
article for theoretical and Difference between PHP regex and JavaScript regex answer for practical information.
Most of the time, you can use Javascript regex patterns in PHP with small modifications. As a fundamental difference, PHP regex is defined as a string (or in a string) like this:
preg_match('/^\(?(\d{3})\)?[- ]?(\d{3})[- ]?(\d{4})$/',$telephone);
Javascript regex is not, it's defined in its own way:
var ptr = new RegExp(/^\(?(\d{3})\)?[- ]?(\d{3})[- ]?(\d{4})$/);
// or
var ptr = /^\(?(\d{3})\)?[- ]?(\d{3})[- ]?(\d{4})$/;
You can give it a try by running the regex on PHP. As a recommendation, do not replace it in Codeigniter files, you can simply extend or replace native library. You can check Creating Libraries out for more information.
I was able to solve this in a better-than-expected manner. I was unable to convert the Javascript regex that I wanted to use (even after purchasing RegexBuddy - it'll come in handy, but it was not able to produce a proper conversion), so I decided to go looking on the Regex Validate Email Address site to see if they had any recommendations anywhere for good regexes. That's when I found this:
"The expression with the best score is currently the one used by PHP's filter_var()":
/^(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){255,})(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){65,}#)(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22))(?:\.(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22)))*#(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\]))$/iD
It matches with only 4/86 errors, while the Javascript one I was using matches with 8/86 errors, so the PHP one is a little more accurate. So, I extended the CodeIgniter Form_validation library to instead use return filter_var($str, FILTER_VALIDATE_EMAIL);.
...But does it work in Javascript?
var pattern = new RegExp(/^(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){255,})(?!(?:(?:\x22?\x5C[\x00-\x7E]\x22?)|(?:\x22?[^\x5C\x22]\x22?)){65,}#)(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22))(?:\.(?:(?:[\x21\x23-\x27\x2A\x2B\x2D\x2F-\x39\x3D\x3F\x5E-\x7E]+)|(?:\x22(?:[\x01-\x08\x0B\x0C\x0E-\x1F\x21\x23-\x5B\x5D-\x7F]|(?:\x5C[\x00-\x7F]))*\x22)))*#(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\]))$/i);
Zing! Works like a charm! Not only did I get the consistency I was looking for between front and back end validation, but I also got a more accurate regex in the process. Double win!
Thank you to all those who provided suggestions!
Today there is exists the site https://regex101.com/ where you can transform one JS regex to PHP or some another languages.
I'm developing a PHP-based web-application in which you have a form with textarea inputs that can accept links via anchor tags. But when I tested it after adding a hyperlink as follows, it pointed to a non-existent local subdirectory:
link
I realized that this was because I had not appended http:// before the link.
there might be cases where a user might input the link just as I did above. In such cases I don't want the link to be pointing as it did above. is there any possible solution, such as automatically appending http:// before the link in case that it doesn't exist? How do I do that?
----------------------------------------Edit---------------------------------------------
Please consider that the anchor tags are amidst other plaintext and this is making things harder to work with.
I'd go for something like this:
if (!parse_url($url, PHP_URL_SCHEME)) {
$url = 'http://' . $url;
}
This is an easy and stable way to check for the presence of a protocol in a URL, and allows others (e.g. ftp, https) that may be entered.
What you're talking about involves two steps, URL detection and URL normalization. First you'll have to detect all the URLs in the string being parsed and store them in a data structure for further processing, such as an array. Then you need to iterate over the array and normalize each URL in turn, before attempting to store them.
Unfortunately, both detection and normalization can be problematic, as a URL has a quite complicated structure. http://www.regexguru.com/2008/11/detecting-urls-in-a-block-of-text/ makes some suggestions, but as the page itself says, no regex URL detection is ever perfect.
There are examples of regular expressions that can detect URLs available from various sites, but in my experience none of them are completely reliable.
As for normalization, Wikipedia has an article on the subject which may be a good starting point. http://en.wikipedia.org/wiki/URL_normalization
I'm using a regex to find any URLs and link them accordingly. However, I do not want to linkify any URLs that are already linked so I'm using lookbehind to see if the URL has an href before it.
This fails though because variable length quantifiers aren't allowed in lookahead and lookbehind for PHP.
Here's the regex for the match:
/\b(?<!href\s*=\s*[\'\"])((?:http:\/\/|www\.)\S*?)(?=\s|$)/i
What's the best way around this problem?
EDIT:
I have yet to test it, but I think the trick to doing it in a single regex is using conditional expressions within the regex, which is supported by PCRE. It would look something like this:
/(href\s*=\s*[\'\"])?(?(1)^|)((?:http:\/\/|www\.)\w[\w\d\.\/]*)(?=\s|$)/i
The key point is that if the href is captured, the match is immediately thrown out due to the conditional (?(1)^|), which is guaranteed to not match.
There's probably something wrong with it. I'll test it out tomorrow.
I tried doing the same thing the other way round: ensure that the URL doesn't end in ">:
/((?:http:\/\/|www\.)(?:[^"\s]|"[^>]|(*FAIL))*?)(?=\s|$)/i
But for me that looks pretty hacky, I'm sure you can do better.
My second approach is more similar to yours (and thus is more precise):
/href\s*=\s*"[^"]*"(*SKIP)(*FAIL)|((?:http:\/\/|www\.)\S*?)(?=\s|$)/i
If I find an href= I (*SKIP)(*FAIL). This means that I jump to the position the regex engine is at, when it encounters the (*SKIP).
But that's no less hacky and I'm sure there is a better alternative.
Finding "every URL that isn't part of a link" is quite difficult negative logic. It may be easier to find every URL, then every URL that's a link, and remove every of the latter from the former list.
As far as finding which URLs are a part of a link, try:
/<a([\s]+[\w="]+)*[\s]+href[\s]*=[\s]*"([\w\s:/.?+&=]+)"([\s]+[\w="]+)*>/i
I tested it with http://regexpal.com/ to be sure. It looks for the <a first, then it allows for any number of parameters, followed by href, followed by any other number of parameters. If it doesn't have the href, it's not a link. If it isn't an <a> tag, it's not a link. Since this is just the list of what we want to remove from the other list (of URLs), I simplified the definition of a URL to [\w\s:/.?+&=]+. As far as generating a list of URLs, you'll want something smarter.
I don't have a better regex. but if you do not find better regex then I would suggest using two queries for the task. First, find and remove all links and then search for urls. This would be easier and faster possibly.
(For, find and replace in one go, you can use something like - http://www.satya-weblog.com/2010/08/php-regex-find-and-replace-any-word-string-or-text-at-one-go.html).