This regex matches and shouldn't. Why is it? - regex

This regex:
^((https?|ftp)\:(\/\/)|(file\:\/{2,3}))?(((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}
(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))|(((([a-zA-Z0-9]+)(\.)?)+?)(\.)([a-z]{2}
|com|org|net|gov|mil|biz|info|mobi|name|aero|jobs|museum))([a-zA-Z0-9\?\=\&\%\/]*)?$
Formatted for readability:
^( # Begin regex / begin address clause
(https?|ftp)\:(\/\/)|(file\:\/{2,3}))? # protocol
( # container for two address formats, more to come later
((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}
(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?) # match IP addresses
)|( # delimiter for address formats
((([a-zA-Z0-9]+)(\.)?)+?) # match domains and any number of subdomains
(\.) #dot for .com
([a-z]{2}|com|org|net|gov|mil|biz|info|mobi|name|aero|jobs|museum) #TLD clause
) # end address clause
([a-zA-Z0-9\?\=\&\%\/]*)? # querystring support, will pretty this up later
$
is matching:
www.google
and shouldn't be. This is one of my "fail" test cases. I have declared the TLD portion of the URL to be mandatory when matching on alpha instead of on IP, and "google" doesn't fit into the "[a-z]{2}" clause.
Keep in mind I will fix the following issues seperately - this question is about why it matches www.google and shouldn't.
Querystring needs to support proper formats only, currently accepts any combination of querystring characters
Several protocols not supported, though the scope of my requirements may not include them
uncommon TLDs with 3 characters not included
Probably matches http://www.google..com - will check for consecutive dots
Doesn't support decimal IP address formats
What's wrong with my regex?
edit: See also a previous problem with an earlier version of this regex on a different test case:
How can I make this regex match correctly?
edit2: Fixed - The corrected regex (as asked) is:
^((https?|ftp)\:(\/\/)|(file\:\/{2,3}))?(((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}
(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))|(((([a-zA-Z0-9]+)(\.)?)+?)(\.)([a-z]{2}|com|org|net|gov|mil|biz|info|mobi|name|aero|jobs|museum))([\/][\/a-zA-Z0-9\.]*)*?([\/]?[\?][a-zA-Z0-9\=\&\%\/]*)?$

"google" might not fit in [a-z]{2}, but it does fit in [a-z]{2}([a-zA-Z0-9\?\=\&\%\/]*)? - you forgot to require a / after the TLD if the URL extends beyond the domain. So it's interpreting it with "www.go" as the domain and then "ogle" following it, with no slash in between. You can fix it by adding a [?/] to the front of that last group to require one of those two symbols between the TLD and any further portion of the URL.

Your TLD clause matches "go" in google and the querystring support part matches "ogle" afterwards. Try changing the querystring part to this:
([?/][a-zA-Z0-9\?\=\&\%\/]*)?

google" doesn't fit into the "[a-z]{2}" clause.
But "go" does and then "ogle" matches "([a-zA-Z0-9\?\=\&\%/]*)?"

Related

Fluentvalidation 6.4.1.0 support me with Incorrect regex

In my case, i want to validate for url image, some url is valid but result is wrong.
Eg: link image is "https://fuvitech.online/wpcontent/uploads/2021/02/bta16600brg.jpg" or "https://fuvitech.online/wp-content/uploads/2021/02/bta16-600brg.jpg" reponse "The image link is not in the correct format".
My code here:
RuleFor(product => product.Images)
.Length(1, 3000).WithMessage(Labels.importProduct_ExceedDescription, p => ImportHelpers.GetColumnName(typeof(ProductEntity).GetProperty(nameof(p.Images))))
.Matches(#"^(http:\/\/|https:\/\/){1}?[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$").WithMessage(Labels.importProduct_UrlNotCorrect, p => ImportHelpers.GetColumnName(typeof(ProductEntity).GetProperty(nameof(p.Images))));
Please help me where the above regex is wrong. Thank you.
Try this:
NOTE the following regex pattern may trigger false positives and also may ignore valid image URLs, because it is very difficult to validate whether a given URL is valid.
^https?:\/\/(?:(?:[A-Za-z0-9]+(?:-[A-Za-z0-9]+)+|[A-Za-z0-9]{2,})\.)+[A-Za-z]{2,}(?::\d+)?\/(?:(?:[A-Za-z0-9]+(?:(?:-[A-Za-z0-9]+)+)?\/)+|)[\w-]+\.(?:jpg|jpeg|png)$
Explanation
^ the start of a line/string.
https?:\/\/ match http with an optional letter s, followed by ://.
(?:(?:[A-Za-z0-9]+(?:-[A-Za-z0-9]+)+|[A-Za-z0-9]{2,})\.)+ This will match things like foo-foo.bar-bar., foo.bar-bar. and foo.
[A-Za-z]{2,} this will match the TLD part, e.g., com, org, this part with the previous part will match things like foo-foo.bar-bar.com, foo.bar-bar.com or foo.com.
(?::\d+)? optional group of (a colon : followed by one or more digits) for port part.
\/(?:(?:[A-Za-z0-9]+(?:(?:-[A-Za-z0-9]+)+)?\/)+|) this check for two things, the first one is /uploads/public-images/, /uploads/images/, the second one is a single /.
[\w-]+ this part for the file name, e.g., bta16-600brg.
\.(?:jpg|jpeg|png) you can add here multiple extensions, you can allow uppercase letters by using for example, [Jj][Pp][Gg] for jpg.
$ the end of the line/string.
See regex demo
Thanks #SaSkY answer my question.
I found my mistake.
This source [.[a-z]{2,5}] only allows domain extensions from 2-5 characters. Example [.com] is valid. But in my case [.online] was not valid.
I changed to [.[a-z]{1,10}].

Regex get domain name from email

I am learning regex and am having trouble getting google from email address
String
first.name#google.com
I just want to get google, not google.com
Regex:
[^#].+(?=\.)
Result: https://regex101.com/r/wA5eX5/1
From my understanding. It ignore # find a string after that until . (dot) using (?=\.)
What did I do wrong?
[^#] means "match one symbol that is not an # sign. That is not what you are looking for - use lookbehind (?<=#) for # and your (?=\.) lookahead for \. to extract server name in the middle:
(?<=#)[^.]+(?=\.)
The middle portion [^.]+ means "one or more non-dot characters".
Demo.
Updated answer:Use a capturing group and keep it simple :)
#(\w+)
Explanation by splitting it up
( capturing group for extraction )
\w stands for word character [A-Za-z0-9_]
+ is a quantifier for one or more occurances of \w
Regex explanation and demo on Regex101
I used the solution's regex for my task, but realized that some of the emails weren't that easy: foo#us.industries.com, foobar#tm.valves.net, andfoo#ge.test.com
To anyone who came here wanting the sub domain as well (or is being cut off by it), here's the regex:
(?<=#)[^.]*.[^.]*(?=\.)
This should be the regex:
(?<=#)[^.]+
(?<=#) - places the search right after the #
[^.]+ - take all the characters that are not dot (stops on dot)
So it extracts google from the email address.
As I was working to get the domain name of email addresses and none corresponded to what I needed:
To not catch subdomains
To match countries top domains (like .com.ar or co.jp)
For example, in test#ext.domain.com.mx I need to match domain.com.mx
So I made this one:
[^.#]*?\.\w{2,}$|[^.#]*?\.com?\.\w{2}$
Here is a link to regex101 to illustrate the regex: https://regex101.com/r/vE8rP9/59
You can get the sumdomain name (without the top-level domain ex: .com or .com.mx) by adding lookaround operators (but it will match twice in test#test.com.mx):
[^.#]*?(?=\.\w{2,}$)|[^.#]*?(?=\.com?\.\w{2}$)
Maybe not strictly a "full regex answer" but more flexible ( in case the part before the # is not "first.last") would be using cut:
cut -d # -f 2 | cut -d . -f 1
The first cut will isolate the part after # and the second one will get what you want.
This will work also for another kinds of email patterns : xxxx#server.com / xxx.yyy.zzz# server.com and so on...
Thanks everyone for your great responses, I took what you had and expanded it with labelled match-groups for easy extraction of separate parts.
Caveat : Regex.Speed = Slow
Another post mentioned how SLOW and nonperformant regexes are, and that is a fair point to remember. My particular need is targeting my own background/slow/reporting processes and therefore it doesn't matter how long it takes.
But it's good to remember whenever possible Regex should NOT be used in any sort of web page load or "needs-to-be-quick" kind of application. In that case you're much better off using substring to algorithmically strip down the inputs and throw away all the junk that I'm optionally matching/allowing/including here.
https://regex101.com/r/ZnU3OC/1
One Regex to rule them all...
Subdomain/Domain/TopLevelDomain/CountryCode extraction for Emails, domain lists, & URLs
Also handles ?Querystring=junk, Slashes/With/Paths, #anchors
Now with more broth, batteries not included
^(?<Email>.*#)?(?<Protocol>\w+:\/\/)?(?<SubDomain>(?:[\w-]{2,63}\.){0,127}?)?(?<DomainWithTLD>(?<Domain>[\w-]{2,63})\.(?<TopLevelDomain>[\w-]{2,63}?)(?:\.(?<CountryCode>[a-z]{2}))?)(?:[:](?<Port>\d+))?(?<Path>(?:[\/]\w*)+)?(?<QString>(?<QSParams>(?:[?&=][\w-]*)+)?(?:[#](?<Anchor>\w*))*)?$
not overly complicated at all... why would you even say that?
Substitution / Outputs
EXAMPLE INPUT: "https://www.stackoverflow.co.uk/path/2?q=mysearch&and=more#stuff"
EXAMPLE OUTPUT:
{
Protocol: "https://"
SubDomain: "www"
DomainWithTLD: "stackoverflow.co.uk"
Domain: "stackoverflow"
TopLevelDomain: "co"
CountryCode: "uk"
Path: "/path/2"
QString: "?q=mysearch&and=more#stuff"
}
Allowed/Compliant Domains : Should ALL MATCH
www.bankofamerica.com
bankofamerica.com.securersite.regexr.com
bankofamerica.co.uk.blahblahblah.secure.com.it
dashes-bad-for-seo.but-technically-still-allowed.not-in-front-or-end
bit.ly
is.gd
foo.biz.pl
google.com.cn
stackoverflow.co.uk
level_three.sub_domain.example.com
www.thelongestdomainnameintheworldandthensomeandthensomemoreandmore.com
https://www.stackoverflow.co.uk?q=mysearch&and=more
foo://5th.4th.3rd.example.com:8042/over/there
foo://subdomain.example.com:8042/over/there?name=ferret#nose
example.com
www.example.com
example.co.uk
trailing-slash.com/
trailing-pound.com#
trailing-question.com?
probably-not-valid.com.cn?&#
probably-not-valid.com.cn/?&#
example.com/page
example.com?key=value
* NOTE: PunyCodes (Unicode in urls) handled just fine with \w ,no extra sauce needed
xn--fsqu00a.xn--0zwm56d.com
xn--diseolatinoamericano-66b.com
Emails : Should ALL MATCH
first.name#google1.co.com
foo#us.industries.com,
foobar#tm.valves.net,
andfoo#ge.test.com
jane.doe#my-bank.no
john.doe#spam.com
jane.ann.doe#sandnes.district.gov
Non-Compliant Domains : Should NOT MATCH
either not long-enough (domain min length 2), or too long (64)
v.gd
thing.y
0123456789012345678901234567890123456789012345678901234567891234.com
its-sixty-four-instead-of-sixty-three!.com
symbols-not-allowed#.com
symbols-not-allowed#.com
symbols-not-allowed$.com
symbols-not-allowed%.com
symbols-not-allowed^.com
symbols-not-allowed&.com
symbols-not-allowed*.com
symbols-not-allowed(.com
symbols-not-allowed).com
symbols-not-allowed+.com
symbols-not-allowed=.com
TBD Not handled:
* dashes as start or ending is disallowed (dropped from Regex for readability)
-junk-.com
* is underscore allowed? i donno... (but it simplifies the regex using \w instead of [a-zA-Z0-9\-] everywhere)
symbols-not-allowed_.com
* special case localhost?
.localhost
also see:
Domain Name Rules :: Super handy ASCII Diagram of a URL
see: https://stackoverflow.com/a/66660651/738895 *
Side NOTE: lazy load '?' for subdomains{0,127}? currently needed for any of the cases with country codes... (example: stackoverflow.co.uk)
Matches these, but does NOT grab $NLevelSubdomains in a match group, can only grab 3rd level only.
This is a relatively simple regex, and it grabs everything between the # and the final domain extension (e.g. .com, .org). It allows domain names that are made up of non-word characters, which exist in real-world data.
>>> regex = re.compile(r"^.+#(.+)\.[\w]+$")
>>> regex.findall('jane.doe#my-bank.no')
['my-bank']
>>> regex.findall('john.doe#spam.com')
['spam']
>>> regex.findall('jane.ann.doe#sandnes.district.gov')
['sandnes.district']
I used this regular expression to get the complete domain name '.*#+(.*)' where .* will ignore all the character before # (by #+) and start extracting cpmlete domain name by mentioning paranthesis and complete string inside(except linebrake characters)

Extracting top-level and second-level domain from a URL using regex

How can I extract only top-level and second-level domain from a URL using regex? I want to skip all lower level domains. Any ideas?
Here's my idea,
Match anything that isn't a dot, three times, from the end of the line using the $ anchor.
The last match from the end of the string should be optional to allow for .com.au or .co.nz type of domains.
Both the last and second last matches will only match 2-3 characters, so that it doesn't confuse it with a second-level domain name.
Regex:
[^.]*\.[^.]{2,3}(?:\.[^.]{2,3})?$
Demonstration:
Regex101 Example
Updated 2019
This is an old question, and the challenge here is a lot more complicated as we start adding new vanity TLDs and more ccTLD second level domains (e.g. .co.uk, .org.uk). So much so, that a regular expression is almost guaranteed to return false positives or negatives.
The only way to reliably get the primary host is to call out to a service that knows about them, like the Public Suffix List.
There are several open-source libraries out there that you can use, like psl, or you can write your own.
Usage for psl is quite intuitive. From their docs:
var psl = require('psl');
// Parse domain without subdomain
var parsed = psl.parse('google.com');
console.log(parsed.tld); // 'com'
console.log(parsed.sld); // 'google'
console.log(parsed.domain); // 'google.com'
console.log(parsed.subdomain); // null
// Parse domain with subdomain
var parsed = psl.parse('www.google.com');
console.log(parsed.tld); // 'com'
console.log(parsed.sld); // 'google'
console.log(parsed.domain); // 'google.com'
console.log(parsed.subdomain); // 'www'
// Parse domain with nested subdomains
var parsed = psl.parse('a.b.c.d.foo.com');
console.log(parsed.tld); // 'com'
console.log(parsed.sld); // 'foo'
console.log(parsed.domain); // 'foo.com'
console.log(parsed.subdomain); // 'a.b.c.d'
Old answer
You could use this:
(\w+\.\w+)$
Without more details (a sample file, the language you're using), it's hard to discern exactly whether this will work.
Example: http://regex101.com/r/wD8eP2
Also, you can likely do that with some expression similar to,
^(?:https?:\/\/)(?:w{3}\.)?.*?([^.\r\n\/]+\.)([^.\r\n\/]+\.[^.\r\n\/]{2,6}(?:\.[^.\r\n\/]{2,6})?).*$
and add as much as capturing groups that you want to capture the components of a URL.
Demo
If you wish to simplify/modify/explore the expression, it's been explained on the top right panel of regex101.com. If you'd like, you can also watch in this link, how it would match against some sample inputs.
RegEx Circuit
jex.im visualizes regular expressions:
For anyone using JavaScript and wanting a simple way to extract the top and second level domains, I ended up doing this:
'example.aus.com'.match(/\.\w{2,3}\b/g).join('')
This matches anything with a period followed by two or three characters and then a word boundary.
Here's some example outputs:
'example.aus.com' // .aus.com
'example.austin.com' // .austin.com
'example.aus.com/howdy' // .aus.com
'example.co.uk/howdy' // .co.uk
Some people might need something a bit cleverer, but this was enough for me with my particular dataset.
Edit
I've realised there are actually quite a few second-level domains which are longer than 3 characters (and allowed). So, again for simplicity, I just removed the character counting element of my regex:
'example.aus.com'.match(/\.\w*\b/g).join('')
Since TLDs now include things with more than three-characters like .wang and .travel, here's a regex that satisfies these new TLDs:
([^.\s]+\.[^.\s]+)$
Strategy: starting at the end of the string, look for one or more characters that aren't periods or whitespace, followed by a single period, followed by one or more characters that aren't periods or whitespace.
http://regexr.com/3bmb3
With capturing groups you can achieve some magix.
For example, consider the following javascript:
let hostname = 'test.something.else.be';
let domain = hostname.replace(/^.+\.([^\.]+\.[^\.]+)$/, '$1');
document.write(domain);
This will result in a string containing 'else.com'. This is because the regex itself will match the complete string and the capturing group will be mapped to $1. So it replaces the complete string 'test.something.else.com' with '$1' which is actually 'else.com'.
The regex isn't pretty and can probably be made more dynamic with things like {3} for defining how many levels deep you want to look for subdomains, but this is just an illustration.
if you want all specific Top Level Domain name then you can write regular expression like this:
[RegularExpression("^(https?:\\/\\/)?(([\\w]+)?\\.?(\\w+\\.((za|zappos|zara|zero|zip|zippo|zm|zone|zuerich|zw))))\\/?$", ErrorMessage = "Is not a valid fully-qualified URL.")]
You can also put more domain name from this link:
https://www.icann.org/resources/pages/tlds-2012-02-25-en
The following regex matches a domain with root and tld extractions (named capture groups) from a url or domain string:
(?:\w+:\/{2})?(?<cs_domain>(?<cs_domain_sub>(?:[\w\-]+\.)*?)(?<cs_domain_root>[\w\-]+(?<cs_domain_tld>(?:\.\w{2})?(?:\.\w{2,3}|\.xn-+\w+|\.site|\.club))))\|
It's hard to say if it is perfect, but it works on all the test data sets that I have put it against including .club, .xn-1234, .co.uk, and other odd endings. And it does it in 5556 steps against 40k chars of logs, so the efficiency seems reasonable too.
If you need to be more specific:
/\.(?:nl|se|no|es|milru|fr|es|uk|ca|de|jp|au|us|ch|it|io|org|com|net|int|edu|mil|arpa)/
Based on http://www.seobythesea.com/2006/01/googles-most-popular-and-least-popular-top-level-domains/

Regex to match anything after /

I'm basically not in the clue about regex but I need a regex statement that will recognise anything after the / in a URL.
Basically, i'm developing a site for someone and a page's URL (Local URL of Course) is say (http://)localhost/sweettemptations/available-sweets. This page is filled with custom post types (It's a WordPress site) which have the URL of (http://)localhost/sweettemptations/sweets/sweet-name.
What I want to do is redirect the URL (http://)localhost/sweettemptations/sweets back to (http://)localhost/sweettemptations/available-sweets which is easy to do, but I also need to redirect any type of sweet back to (http://)localhost/sweettemptations/available-sweets. So say I need to redirect (http://)localhost/sweettemptations/sweets/* back to (http://)localhost/sweettemptations/available-sweets.
If anyone could help by telling me how to write a proper regex statement to match everything after sweets/ in the URL, it would be hugely appreciated.
To do what you ask you need to use groups. In regular expression groups allow you to isolate parts of the whole match.
for example:
input string of: aaaaaaaabbbbcccc
regex: a*(b*)
The parenthesis mark a group in this case it will be group 1 since it is the first in the pattern.
Note: group 0 is implicit and is the complete match.
So the matches in my above case will be:
group 0: aaaaaaaabbbb
group 1: bbbb
In order to achieve what you want with the sweets pattern above, you just need to put a group around the end.
possible solution: /sweets/(.*)
the more precise you are with the pattern before the group the less likely you will have a possible false positive.
If what you really want is to match anything after the last / you can take another approach:
possible other solution: /([^/]*)
The pattern above will find a / with a string of characters that are NOT another / and keep it in group 1. Issue here is that you could match things that do not have sweets in the URL.
Note if you do not mind the / at the beginning then just remove the ( and ) and you do not have to worry about groups.
I like to use http://regexpal.com/ to test my regex.. It will mark in different colors the different matches.
Hope this helps.
I may have misunderstood you requirement in my original post.
if you just want to change any string that matches
(http://)localhost/sweettemptations/sweets/*
into the other one you provided (without adding the part match by your * at the end) I would use a regular expression to match the pattern in the URL but them just blind replace the whole string with the desired one:
(http://)localhost/sweettemptations/available-sweets
So if you want the URL:
http://localhost/sweettemptations/sweets/somethingmore.html
to turn into:
http://localhost/sweettemptations/available-sweets
and not into:
localhost/sweettemptations/available-sweets/somethingmore.html
Then the solution is simpler, no groups required :).
when doing this I would make sure you do not match the "localhost" part. Also I am assuming the (http://) really means an optional http:// in front as (http://) is not a valid protocol prefix.
so if that is what you want then this should match the pattern:
(http://)?[^/]+/sweettemptations/sweets/.*
This regular expression will match the http:// part optionally with a host (be it localhost, an IP or the host name). You could omit the .* at the end if you want.
If that pattern matches just replace the whole URL with the one you want to redirect to.
use this regular expression (?<=://).+

parse url from string in coldfusion

i need to parse all urls from a paragraph(string)
eg.
"check out this site google.com and don't forget to see this too bing.com/maps"
it should return "google.com and bing.com/maps"
i'm currently using this and its not to perfection.
reMatch("(^|\s)[^\s#]+\.[^\s#\?\/]{2,5}((\?|\/)\S*)?",mystring)
thanks
You need to define more clearly what you consider a URL
For example, I might use something such as this:
(?:https?:)?(?://)?(?:[\w-]+\.)+[a-z]{2,6}(?::\d+)?(?:/[\w.,-]+)*(?:\?\S+)?
(use with reMatchNoCase or plonk (?i) at front to ignore case)
Which specifically only allows alphanumerics, underscore, and hyphen in domain and path parts, requires the TLD to be letters only, and only looks for numeric ports.
It might be this is good enough, or you may need something that looks for more characters, or perhaps you want to trim things likes quotes, brackets, etc off the end of the URL, or whatever - it depends on the context of what you're doing as to whether you'd like to err towards missing URLs or detecting non-URLs.
(I'd probably go for the latter, then potentially run a secondary filter to verify if something is a URL, but that takes more work, and may not be necessary for what you're doing.)
Anyhow, the explanation of the above expression is below, hopefully with clear comments to help it make sense. :)
(Note that all groups are non-capturing (?:...) since we don't need the indiv parts.)
# PROTOCOL
(?:https?:)? # optional group of "http:" or "https:"
# SERVER NAME / DOMAIN
(?://)? # optional double forward slash
(?:[\w-]+\.)+ # one or more "word characters" or hyphens, followed by a literal .
# grouped together and repeated one or more times
[a-z]{2,6} # as many as 6 alphas, but at least 2
# PORT NUMBER
(?::\d+)? # an optional group made up of : and one or more digits
# PATH INFO
(?:/[\w.,-]+)* # a forward slash then multiple alphanumeric, underscores, or hyphens
# or dots or commas (add any other characters as required)
# in a group that might occur multiple times (or not at all)
# QUERY STRING
(?:\?\S+)? # an optional group containing ? then any non-whitespace
Update:
To prevent the end of email addresses being matched, we need to use a lookbehind, to ensure that prior to the URL we don't have an # sign (or anything else unwanted) but without actually including that prior character in the match.
CF's regex is Apache ORO which doesn't support lookbehinds, but we can use the java.util.regex nice and easily with a component I have created which does support lookbehinds.
Using that is as simple as:
<cfset jrex = createObject('component','jre-utils').init('CASE_INSENSITIVE') />
...
<cfset Urls = jrex.match( regex , input ) />
After the createObject, it should basically be like using the built-in re~ stuff, but with the slight syntax difference, and the different regex engine under the hood.
(If you have any problems or questions with the component, let me know.)
So, on to your excluding emails from URL matching problem:
We can either do a (?<=positive) or (?<!negative) lookbehind, depending on if we want to say "we must have this" or "we must not have this", like so:
(?<=\s) # there must be whitespace before the current position
(?<!#) # there must NOT be an # before current position
For this URL example, I would expand either of those examples to:
(?<=\s|^) # look for whitespace OR start of string
or
(?<![#\w/]) # ensure there is not a # or / or word character.
Both will work (and can be expanded with more chars), but in different ways, so it simply depends which method you want to do it with.
Put whichever one you like at the start of your expression, and it should no longer match the end of abcd#gmail.com, unless I've screwed something up. :)
Update 2:
Here is some sample code which will exclude any email addresses from the match:
<cfset jrex = createObject('component','jre-utils').init('CASE_INSENSITIVE') />
<cfsavecontent variable="SampleInput">
check out this site google.com and don't forget to see this too bing.com/maps
this is an email#somewhere.com which should not be matched
</cfsavecontent>
<cfset FindUrlRegex = '(?<=\s|^)(?:https?:)?(?://)?(?:[\w-]+\.)+[a-z]{2,6}(?::\d+)?(?:/[\w.,-]+)*(?:\?\S+)?' />
<cfset MatchedUrls = jrex.match( FindUrlRegex , SampleInput ) />
<cfdump var=#MatchedUrls#/>
Make sure you have downloaded the jre-utils.cfc from here and put in an appropriate place (e.g. same directory as script running this code).
This step is required because the (?<=...) construct does not work in CF regular expressions.