Short version:
How can I get a regex that matches a#a.aaaa but not a#a.aaaaa using CAtlRegExp ?
Long version:
I'm using CAtlRegExp http://msdn.microsoft.com/en-us/library/k3zs4axe(VS.80).aspx to try to match email addresses. I want to use the regex
^[A-Z0-9._%+-]+#(?:[A-Z0-9-]+\.)+[A-Z]{2,4}$
extracted from here.
But the syntax that CAtlRegExp accepts is different than the one used there. This regex returns the error REPARSE_ERROR_BRACKET_EXPECTED, you can check for yourself using this app: http://www.codeproject.com/KB/string/mfcregex.aspx
Using said app, I created this regex:
^[a-zA-Z0-9\._%\+\-]+#([a-zA-Z0-9-]+\.)+[a-zA-Z]$
But the problem is this matches a#a.aaaaa as valid, I need it to match 4 characters maximum for the op-level domain.
So, how can I get a regex that matches a#a.aaaa but not a#a.aaaaa ?
Try: ^[a-zA-Z0-9\._%\+\-]+#([a-zA-Z0-9-]+\.)+\c\c\c?\c?$
This expression replaces the [A-Z]{2,4} sequence which CAtlRegExp doesn't support with \c\c\c?\c?
\c serves as an abbreviation of [a-zA-Z]. The question marks after the 3rd and 4th \c's indicate they can match either zero or one characters. As a result, this portion of the expression matches 2, 3 or 4 characters, but neither more nor less.
You are trying to match email addresses, a very widely used critical element of internet communication.
To which I would say that this job is best done with the most widely used most correct regex.
Since email address format rules are described by RFC822, it seems useful to do internet searches for something like "RFC822 email regex".
For Perl the answer seems to be easy: use Mail::RFC822::Address: regexp-based address validation
RFC 822 Email Address Parser in PHP
Thus, to achieve the most correct handling of email addresses, one should either locate the most precise regex that there is out somewhere for the particular toolkit (ATL in your case) or - in case there's no suitable existing regex yet - adapt a very precise regex of another toolkit (Perl above seems to be a very complete albeit difficult candidate).
If you're trying to match a specific sub part of email addresses (as seems to be the case given your question), then it probably still makes sense to start with the most up-to-date/correct/universal regex and specifically limit it to the parts that you require.
Perhaps I stated the obvious, but I hope it helped.
Related
I am trying to craft some regex that can match all of the following strings (no more, no less):
ftp
ftps
sftp
ftpes
The closest I have gotten is: ^ftps?$ but as you can tell that only matches the top two. How can I match all of the ones listed? I am aware that I can use something like ^(ftp|ftps|sftp|ftpes)$ but I wanted to save as much space as possible (my actual application is much much larger than this so space saving is more necessary. I used the ftp example for visual appeal).
I am using this in a bash 3.2.57(1)-release if-statement.
I suggest this extended regex:
^(ftpe?s|s?ftp)$
ftpe?s: one e is optional
s?ftp: one s is optional
See: The Stack Overflow Regular Expressions FAQ
A variation on an extended regex would be:
^(s?ftp|^ftp(s|es)?)$
Here:
(^s?ftp| zero or one 's' followed by ftp at the beginning
or
ftp followed by (s|es)?$ zero or one 's' or 'es' after.
Let me know if you have further questions.
I have this regex for email validation (assume only x#y.com, abc#defghi.org, something#anotherhting.edu are valid)
/^[a-zA-Z0-9]+#[a-zA-Z0-9]\.(com)|(edu)|(org)$/i
But #abc.edu and abc#xyz.eduorg are both valid as to the regex above. Can anyone explain why that is?
My approach:
there should be at least one character or number before #
then there comes #
there should be at least one character or number after # and before .
the string should end with either edu, com, or org.
Try this
/^[a-zA-Z0-9]+#[a-zA-Z0-9]+\.(com|edu|org)$/i
and it should become clear - you need to group those alternatives, otherwise you can match any string that has 'edu' in it, or any string that ends with org. To put it another way, your version matches any of these patterns
^[a-zA-Z0-9]+#[a-zA-Z0-9]\.(com)
(edu)
(org)$
It's worth pointing out that the original poster is using this as a regex learning exercise. This would be a terrible regex for actual production use! It's a thorny problem - see Using a regular expression to validate an email address for a lot more depth.
Your grouping parentheses are incorrect:
/^[a-zA-Z0-9]+#[a-zA-Z0-9]+\.(com|edu|org)$/i
Can also just use one case as you're using the i modifier:
/^[a-z0-9]+#[a-z0-9]+\.(com|edu|org)$/i
N.B. you were also missing a + from the second set, I assume this was just a typo...
What you have written is the equivalent of matching something that:
Begins with [a-zA-Z0-9]+#[a-zA-Z0-9].com
contains edu
or ends with org
What you were looking for was:
/^[a-z0-9]+#[a-z0-9]+\.(com|edu|org)$/i
Your regex looks ok.
I guess you are looking using a find function in stead of a match function
Without specifying what you use it is a bit difficult, but in Python you would write
import re
pattern = re.compile ('^[a-zA-Z0-9]+#[a-zA-Z0-9]\.(com)|(edu)|(org)$')
re.match('#abc.edu') # fails, use this to validate an input
re.search('#abc.edu') # matches, finds the edu
Try to use it:
[a-zA-Z0-9]+#[a-zA-Z0-9]+.(com|edu|org)+$
U forget about + modificator if u want to catch any combinations of (com|edu|org)
Upd: as i see second [a-zA-Z0-9] u missed + too
I am a email spam quarantine administrator and I can write regular expression rules to block email messages. There is a common classification of email spam hitting our domain such that the username of any of our email addresses is spoofed in front of some other domain.
For example, suppose my email address is jwclark#domain.com. In that case, spammers are writing to me from all kinds of other domains that start with my username such as:
jwclark1234#whatever.com
jwclark#wrongdomain.com
jwclark#a.domain.com
How can I write a regular expression rule to match everything including jwclark and any wildcards, but not match the original jwclark#domain.com? I would like a regex that matches everything above except for my actual example email address jwclark#domain.com.
I've made this regexp here
^jwclark.*[#](?!domain\.com).*$
it's in javascript format, but it should be easy to adapt to php or something else.
Given the nature of your problem, you might be better off making a regex builder function that makes the proper regexp for you, given the parameters.
Or, actually use a different approach. I recently found out how to parse ranges of floating point numbers with regexp, but that doesn't make it the proper solution to finding numbers within ranges. :P
edit - fixed silly redundancy thanks to zx81
edit - change to comply with strange limitations:
^jwclark.{0,25}[#][^d][^o][^m][^a][^i][^n].{0,25}\.com.{0,25}$
demo for the strange one
I am using solr to fetch data.
I was using below parameters to fetch data:
http://testURL/solr/core0/select?start=10&rows=10&hl.fl=CC&hl.requireFieldMatch=true&hl=on&hl.maxAnalyzedChars=1&hl.fragsize=145&hl.snippets=99&sort=COlumn1+desc&q=CC%3a%28%22test%22~2%29&fl=title120%2ccolumn2%2ccolumn3%2cRL_DateTime%2cSid%2ccolumn4%2cguid%2chour&hl.regex.pattern=^\d+%20%3E%3E%20
Above query is not working with hl.regex.pattern parameter.
If I remove "hl.regex.pattern" than it is providing results in highlight section.
If I provide that regex pattern than it will not.
Regex is working in my c# code.
So am I missing anything here?
It's almost certainly the ^\. Those aren't valid in a URI, so you'll have to escape them.
From RFC 1738:
only alphanumerics, the special characters "$-_.+!*'(),", and
reserved characters used for their reserved purposes may be used
unencoded within a URL.
This is a little dated, since non-Roman alphanumerics like λάμδα are allowed now, but the gist is the same.
Try hl.regex.pattern=%5E%5Cd+%20%3E%3E%20 instead.
I'm looking for the regex to validate hostnames. It must completely conform to the standard. Right now, I have
^[0-9a-z]([0-9a-z\-]{0,61}[0-9a-z])?(\.[0-9a-z](0-9a-z\-]{0,61}[0-9a-z])?)*$
but it allows successive hypens and hostnames longer than 255 characters. If the perfect regex is impossible, say so.
Edit/Clarification: a Google search didn't reveal that this is a solved (or proven unsolvable) problem. I want to to create the definitive regex so that nobody has to write his own ever. If dialects matter, I want a a version for each one in which this can be done.
^(?=.{1,255}$)[0-9A-Za-z](?:(?:[0-9A-Za-z]|-){0,61}[0-9A-Za-z])?(?:\.[0-9A-Za-z](?:(?:[0-9A-Za-z]|-){0,61}[0-9A-Za-z])?)*\.?$
The approved answer validates invalid hostnames containing multiple dots (example..com). Here is a regex I came up with that I think exactly matches what is allowable under RFC requirements (minus an ending "." supported by some resolvers to short-circuit relative naming and force FQDN resolution).
Spec:
<hname> ::= <name>*["."<name>]
<name> ::= <letter-or-digit>[*[<letter-or-digit-or-hyphen>]<letter-or-digit>]
Regex:
^([a-zA-Z0-9](?:(?:[a-zA-Z0-9-]*|(?<!-)\.(?![-.]))*[a-zA-Z0-9]+)?)$
I've tested quite a few permutations myself, I think it is accurate.
This regex also does not do length validation. Length constraints on labels betweens dots and on names are required by RFC, but lengths can easily be checked as second and third passes after validating against this regex, by checking full string length, and by splitting on "." and validating all substrings lengths. E.g., in JavaScript, label length validation might look like: "example.com".split(".").reduce(function (prev, curr) { return prev && curr.length <= 63; }, true).
Alternative Regex (without negative lookbehind, courtesy of the HTML Living Standard):
^[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$
Your answer was relatively close.
But see
RFC 2396 Section 3.2.2
JaredPar's reference to this answer is referring to Regexp/Common/URI/RFC2396.pm source.
For a hostname RE, that perl module produces
(?:(?:(?:(?:[a-zA-Z0-9][-a-zA-Z0-9]*)?[a-zA-Z0-9])[.])*(?:[a-zA-Z][-a-zA-Z0-9]*[a-zA-Z0-9]|[a-zA-Z])[.]?)
I would modify to be more accurate as:
(?:(?:(?:(?:[a-zA-Z0-9][-a-zA-Z0-9]{0,61})?[a-zA-Z0-9])[.])*(?:[a-zA-Z][-a-zA-Z0-9]{0,61}[a-zA-Z0-9]|[a-zA-Z])[.]?)
Optionally anchoring the ends with ^$ to ONLY match hostnames.
I don't think a single RE can accomplish an full validation because, according to Wikipedia, there is a 255 character length restriction which i don't think can be included within that same RE, at least not without a ton of changes, but it's easy enough to just check the length <= 255 before running the RE.
Take a look at the following question. A few of the answers have regex expressions for host names
Regular expression to match DNS hostname or IP Address?
Could you specify what language you want to use this regex in? Most languages / systems have slightly different regex implementations that will affect people's answers.
I tried all answers with these examples below and unfortunately no one has passed the test.
ec2-11-111-222-333.cd-blahblah-1.compute.amazonaws.com
domaine.com
subdomain.domain.com
12533d5.dkkkd.com
2dotsextension.co
1dotextension.c
ekkej_dhh.com
12552.2225
112.25.25
12345.com
12345.123.com
domaine.123
whatever
9999-ee.99
email#domain.com
.jjdj.kkd
-subdomain.domain.com
#subdomain.domain.com
112.25.25
Here is a better solution.
^[A-Za-z0-9][A-Za-z0-9-.]*\.\D{2,4}$
Just please post any other not considered case if exists # https://regex101.com/r/89zZkW/1
What about:
^(?=.{1,255})([0-9A-Za-z]|_{1}|\*{1}$)(?:(?:[0-9A-Za-z]|\b-){0,61}[0-9A-Za-z])?(?:\.[0-9A-Za-z](?:(?:[0-9A-Za-z]|\b-){0,61}[0-9A-Za-z])?)*\.?$
for matching only one '_' (for some SRV) at the beginning and only one * (in case of a label for a DNs wildcard)
According to the relevant internet RFCs and assuming you have lookahead and lookbehind positive and negative assertions:
If you want to validate a local/leaf hostname for use in an internet hostname (e.g. - FQDN), then:
^(?!-)[-a-zA-Z0-9]{1,63}(?<!-)$
That ^^^ is also the general check that a label component inside an internet hostname is valid.
If you want to validate an internet hostname (e.g. - FQDN), then:
^(?=.{1,253}\.?$)(?:(?!-)[-a-zA-Z0-9]{1,63}(?<!-)\.)*(?!-)[-a-zA-Z0-9]{1,63}(?<!-)\.?$