For some reason I always get stuck making anything past extremely basic regular expressions.
I'm trying to make a regular expression that kind of looks like a URL. I only want basic checking.
I would like it to match the following patterns where X is "something".
X://X.X
X://X.X... etc.
X.X
X.X... etc
If the string contains one of these patterns, it is sufficient checking for me. This way a url like www.example.com:8888 will still match. I have tried many different REGEX combinations with preg_match and cannot seem to get any to behave the way I want it to. I have consulted many other related REGEX questions on SO but my readings have not helped me.
Any help? I will be happy to provide more information if you would like but I don't know what else you would need.
It takes practice but here is one that I made using a regex tester (http://www.regextester.com/) to check my pattern:
^.+(:\/\/|\.)([a-zA-Z0-9]+\.)+.+
My approach is to slowly build my pattern from the beginning and add on one piece at a time. This cheatsheet is extremely helpful for remembering http://www.cheatography.com/davechild/cheat-sheets/regular-expressions/ what everything is.
Basically the pattern starts at the beginning of the string and checks for any characters followed by either :// or . then checks for groupings of letters and numbers followed by a . ending with any number of characters.
The pattern could probably be improved with groupings to not pass on invalid characters. But this one was quick and dirty. You could replace the first and last . with the characters that would be valid.
UPDATE
Per the comments here is an updated pattern:
^.+?(:\/\/|\.)?([a-zA-Z0-9]+?\.)+.+
/^(.+:\/\/)?[^.]+\.[^.\/]+([.\/][^.\/]+)*$/
Related
Hello everyone I'm trying to validate if input has correct data. I need to check it input is number in pattern xx,xx or xxx. For example if user put 100 or 120,32 it will pass the validation. I'm trying to make regular expression for this but I'm not good in this topic. I have working code for xx,xx but how can I add to check first or second option to don't throw an error? Here is what I've got:
/^[+]?\d+\,\d+/
Your question
For the examples you mentioned, this would match all occurences:
/\d{2,3}(,\d{2})?)/
It says (in basic english): Two to three digits, followed by an optional "comma and two digits". For explanation, also see the example on Regex101: https://regex101.com/r/hU5kJ7/1
However I do not see any reason why you would limit the digits before the floating point to 3 digits, so to make it open, you could just leave out the 3:
/\d{2,}(,\d{2})?)/
It says (in basic english): Two to unlimited digits, followed by an optional "comma and two digits".
Apart from that
I would really not recommend implementing something that basic like number (or currency?) validation by yourself again. It is like reinventing the wheel. You will find many and many validation implementations like that all over the internet, in so called validation libraries or frameworks.
This regex should solve your problem:
/^\d+(,\d+)?/
I'm working on a web page and regex keeps coming up as the best way to handle string manipulation for an issue I'm trying to resolve. Unfortunately, regex is not exactly trivial and I've been having trouble. Any help is appreciated;
I would like to make strings entered from a php form into clickable links. I've received help with my first challenge; how to make strings starting with http, https or ftp into clickable links;
function make_links_clickable($message){
return preg_replace('!(((f|ht)tp(s)?://)[-a-zA-Zа-яА-Я()0-9#:%_+.~#?&;//=]+)!i', '$1', $message);
}
$message = make_links_clickable($message);
And this works well. When I look at it (and do some research), the best that I can glean from the syntax is that the first piece is matching ftp, http, and https, :, and // along with a wide range of combined patterns. I would like to know how I can;
1) Make links starting with www, or ending with .com/.net/.org/etc clickable (like google.com, or www.google.com - leaving out the http://)
2) Change youtube links like
"https://www.youtube.com/watch?v=examplevideo"
into
"<iframe width="560" height="315" src="//www.youtube.com/embed/examplevideo" frameborder="0" allowfullscreen></iframe>"
I think these two cases are basically doing the same kind of thing, but figuring out is not intuitive. Any help would be deeply appreciated.
The first regular expression there is made to match almost everything that follows ftp://, http://, https:// that occurs, so it might be best to implement the others as separate expressions since they'll only be matching hostnames.
For number 1, you'll need to decide how strictly you wish to match different TLDs (.com/.net/etc). For example, you can explicitly match them like this:
(www\.)?[a-z0-9\-]+\.(com|net|org)
However, that will only match URLs that end in .com, .net, or .org. If you want all top-level domains and only the valid ones, you'll need to manually write them all in to the end of that. Alternatively, you can do something like this,
(www\.)?[a-z0-9\-]+\.[a-z]{2,6}
which will accept anything that looks like a url and ends with "dot", and any combination of 2 to 6 letters (.museum and .travel). However, this will match strings like "fgs.fds". Depending on your application, you may need to add more characters to [a-z], to add support for extended character alphabets.
Edit (2 Aug 14): As pointed out in the comments below, this won't match TLDs like .co.uk. Here's one that will:
(www\.)?[a-z0-9\-]+\.([a-z]{2,3}(\.?[a-z]{2,3})?)
Instead of any string between two and six characters (following a period), this will match any two to three, then another one to three (if present), with or without a dividing period.
It'd be redundant, but you could instead remove the question mark after www on the second option, then do both tests; that way, you can match any string ending in a common TLD, or a string that begins with "www." and is followed by any characters with one period separating them, "gpspps.cobg". It would still match sites that might not actually exist, but at least it looks like a url, at it would look like one.
For the YouTube one, I went a little question mark crazy.
(?i:(?:(?:http(?:s)?://)?(?:www\.)?)?youtu(?:\.be/|be\.com/watch\?(?:[a-z0-9_\-\%\&\=]){0,}?v\=))([a-zA-Z0-9_\-]{11}){0,}?v\=))(?i)([a-zA-Z0-9_\-]{11})
EDIT: I just tried to use the above regex in one of my own projects, but I encountered some errors with it. I changed it a little and I think this version may be better:
(?i:(?:(?:http(?:s)?://)?(?:www\.)?)?youtu(?:\.be/|be\.com/watch\?(?:[a-z0-9_\-\%\&\=]){0,})?)(?:v=)?([a-zA-Z0-9_\-]{11})
For those not familiar with regular expressions, parentheses , ( ...regex... ), are stored as groups, which can be selectively picked out of matched strings. Parenthesis groups that begin with ?: as in most of the ones up there, (?:www\.) are however not captured within the groups. Because the end of that regex was left as a normal—"captured"—group, ([a-zA-Z0-9_\-]{11}), you use the $matches argument of functions like preg_match, then you can use $matches[1] to get the YouTube ID of the video, 'examplevide', then work with it however you'd like. Also note, the regex is only matching 11 characters for the ID.
This regex will match pretty much any of the current youtube url formats including incorrect cases, and out of (normal) order parameters:
http://youtu.be/dQw4w9WgXcQ
https://www.youtube.com/watch?v=dQw4w9WgXcQ
http://www.youtube.com/watch?v=dQw4w9WgXcQ&feature=featured
http://www.youtube.com/watch?feature=featured&v=dQw4w9WgXcQ
http://WWW.YouTube.Com/watch?v=dQw4w9WgXcQ
http://YouTube.Com/watch?v=dQw4w9WgXcQ
www.youtube.com/watch?v=dQw4w9WgXcQ
I am trying to create a fairly simple regular expression to use with preg_match() used to check user agent strings for possible web crawlers/spiders.
For example, right now I am using something similar to this:
preg_match("/(bot|search|web|slurp|crawl)/i")
which seems to be successfully matching user agents that contain something like "googlebot" or "webcrawler".
However, the problem I am having is that this also matches when the user agent contains something as common as "webkit".
What modifications would be necessary to prevent specific words such as "webkit" from being matched? I have very little understanding of regular expressions and have spent hours trying various combinations based off answers to other questions and have had no success so far.
Many thanks in advance :)
In order to exclude a certain list of words, you can combine two lookaheads:
(?!webkit|robot)(?=bot|search|web|slurp|crawl)
Apparently the first part would be your exclusion list. This would match "web" but not "webkit"
A small note on the syntax. (?!regex) is negative lookahead and (?=regex) is a positive lookahead (non-consuming regular expression). You can read more upon it here.
In short, a lookahead means "match regex expr but after that continue matching at the original match-point."
I am trying to create a single regular expression that I can use to extract the number from two different urls in a PHP function. The format of these urls are:
/t/2121/title/
and
/top2121.html
I am bad at regular expressions and have already tried the following and many variants of it:
#^/t/(\d+?)/|/top(\d+?)\.html/#i
This is not doing anything and I am still at a complete loss after reading many sites and tutorials on regular expressions. Is there a regular expression I could create that would allow me to extra the number regardless of the url format entered?
Regex to extract only the digits while also checking if url matches accepted formats:
#^\/t(?:\/(\d+)\/[a-z_-]+\/?|op(\d+)\.html)$#i edit: captures in 2 groups
Explained demo here: http://regex101.com/r/dO5dI4
Variant #2: captures in the same group
#^\/t(?|\/(\d+)\/[a-z_-]+\/?$|op(\d+)\.html$)#i
Explained demo here: http://regex101.com/r/cG9vC3
if you just want the first digits after t regardless of the / between, something like this might work: #t/?(\d+)#i
edit:
example: http://codepad.viper-7.com/0z3ee0
I was able to get this regexp to match both types of url formats:
#^/(?:(?:t/)|(?:top))(\d+)(?:(?:\.html)|(?:/))#i
If anyone has a more efficient way of performing the same regexp, I would love to hear it.
If you got either one of these URL's you could use this expression. Your numbers should be stored in your second position:
#^/t(op|/)(\d+)(\.html|/.*)#i
Are there ever going to be numbers in the URL that you don't care about? If not, you can keep this simple by just capturing the numbers and ignoring the rest:
#(\d+)#
I'm getting insane over this, it's so simple, yet I can't figure out the right regex. I need a regex that will match blacklisted words, ie "ass".
For example, in this string:
<span class="bob">Blacklisted word was here</span>bass
I tried that regex:
((?!class)ass)
That matches the "ass" in the word "bass" bot NOT "class".
This regex flags "ass" in both occurences. I checked multiple negative lookaheads on google and none works.
NOTE: This is for a CMS, for moderators to easily find potentially bad words, I know you cannot rely on a computer to do the filtering.
If you have lookbehind available (which, IIRC, JavaScript does not and that seems likely what you're using this for) (just noticed the PHP tag; you probably have lookbehind available), this is very trivial:
(?<!cl)(ass)
Without lookbehind, you probably need to do something like this:
(?:(?!cl)..|^.?)(ass)
That's ass, with any two characters before as long as they are not cl, or ass that's zero or one characters after the beginning of the line.
Note that this is probably not the best way to implement a blacklist, though. You probably want this:
\bass\b
Which will match the word ass but not any word that includes ass in it (like association or bass or whatever else).
It seems to me that you're actually trying to use two lists here: one for words that should be excluded (even if one is a part of some other word), and another for words that should not be changed at all - even though they have the words from the first list as substrings.
The trick here is to know where to use the lookbehind:
/ass(?<!class)/
In other words, the good word negative lookbehind should follow the bad word pattern, not precede it. Then it would work correctly.
You can even get some of them in a row:
/ass(?<!class)(?<!pass)(?<!bass)/
This, though, will match both passhole and pass. ) To make it even more bullet-proof, we can add checking the word boundaries:
/ass(?<!\bclass\b)(?<!\bpass\b)(?<!\bbass\b)/
UPDATE: of course, it's more efficient to check for parts of the string, with (?<!cl)(?<!b) etc. But my point was that you can still use the whole words from whitelist in the regex.
Then again, perhaps it'd be wise to prepare the whitelists accordingly (so shorter patterns will have to be checked).
Is this one is what you want ? (?<!class)(\w+ass)