I am trying to make a regular expression that grabs the first word (including possible leading white space) of each line. Here it is:
/^([\s]+[\S]*).*$/\1//
This code does not seem to be working (see http://regexr.com?34o6m). The code is supposed to
Begin at the start of the line
Create a capturing group where it places the first word (with possible leading white space)
Grab the rest of the line
Substitute the entire line with just the inside of the first capturing group
I tried another version also:
/\S(?<=\s).*^//
It looks like this one fails too (http://regexr.com?34o6s). The goal here was to
Find the first non-whitespace character.
Look behind to make sure it has a whitespace character behind it (i.e. not the first letter of the line).
Grab the rest of the line.
Erase everything the expression just grabbed.
Any insight to what is going wrong would be greatly appreciated. Thanks!
Try this regular expression
^(\s*.*?\s).*
Demo: gskinner
You mixed up your + and *.
/^([\s]*[\S]+).*$/\1/
This means zero or more spaces followed by one or more non-spaces.
You might also want to use $1 instead of \1:
/^([\s]*[\S]+).*$/$1/
Okay, well this seems to work using replace() in Javascript:
/^([\s]*[\S]+).*$/
I tested it on www.altastic.com/regexinator, which as far as I know is accurate [I made it though, so it may not be ;-) ]
remove the first two words
#"^.asterisk? .asterisk? "
this works for me
when posted, the asterisk sign doesn't show. have no idea.
if you want to remove the first word, simply start the regex as follow
a dot sign
an asterisk sign
a question mark
a space
replace with ""
Related
I've been looking around and could not make this happen. I am not totally noob.
I need to get text delimited by (including) START and END that doesn't contain START. Basically I can't find a way to negate a whole word without using advanced stuff.
Example string:
abcSTARTabcSTARTabcENDabc
The expected result:
STARTabcEND
Not good:
STARTabcSTARTabcEND
I can't use backward search stuff. I am testing my regex here: www.regextester.com
Thanks for any advice.
Try this
START(?!.*START).*?END
See it here online on Regexr
(?!.*START) is a negative lookahead. It ensures that the word "START" is not following
.*? is a non greedy match of all characters till the next "END". Its needed, because the negative lookahead is just looking ahead and not capturing anything (zero length assertion)
Update:
I thought a bit more, the solution above is matching till the first "END". If this is not wanted (because you are excluding START from the content) then use the greedy version
START(?!.*START).*END
this will match till the last "END".
START(?:(?!START).)*END
will work with any number of START...END pairs. To demonstrate in Python:
>>> import re
>>> a = "abcSTARTdefENDghiSTARTjlkENDopqSTARTrstSTARTuvwENDxyz"
>>> re.findall(r"START(?:(?!START).)*END", a)
['STARTdefEND', 'STARTjlkEND', 'STARTuvwEND']
If you only care for the content between START and END, use this:
(?<=START)(?:(?!START).)*(?=END)
See it here:
>>> re.findall(r"(?<=START)(?:(?!START).)*(?=END)", a)
['def', 'jlk', 'uvw']
The really pedestrian solution would be START(([^S]|S*S[^ST]|ST[^A]|STA[^R]|STAR[^T])*(S(T(AR?)?)?)?)END. Modern regex flavors have negative assertions which do this more elegantly, but I interpret your comment about "backwards search" to perhaps mean you cannot or don't want to use this feature.
Update: Just for completeness, note that the above is greedy with respect to the end delimiter. To only capture the shortest possible string, extend the negation to also cover the end delimiter -- START(([^ES]|E*E[^ENS]|EN[^DS]|S*S[^STE]|ST[^AE]|STA[^RE]|STAR[^TE])*(S(T(AR?)?)?|EN?)?)END. This risks to exceed the torture threshold in most cultures, though.
Bug fix: A previous version of this answer had a bug, in that SSTART could be part of the match (the second S would match [^T], etc). I fixed this but by the addition of S in [^ST] and adding S* before the non-optional S to allow for arbitrary repetitions of S otherwise.
May I suggest a possible improvement on the solution of Tim Pietzcker?
It seems to me that START(?:(?!START).)*?END is better in order to only catch a START immediately followed by an END without any START or END in between. I am using .NET and Tim's solution would match also something like START END END. At least in my personal case this is not wanted.
[EDIT: I have left this post for the information on capture groups but the main solution I gave was not correct.
(?:START)((?:[^S]|S[^T]|ST[^A]|STA[^R]|STAR[^T])*)(?:END)
as pointed out in the comments would not work; I was forgetting that the ignored characters could not be dropped and thus you would need something such as ...|STA(?![^R])| to still allow that character to be part of END, thus failing on something such as STARTSTAEND; so it's clearly a better choice; the following should show the proper way to use the capture groups...]
The answer given using the 'zero-width negative lookahead' operator "?!", with capture groups, is: (?:START)((?!.*START).*)(?:END) which captures the inner text using $1 for the replace. If you want to have the START and END tags captured you could do (START)((?!.*START).*)(END) which gives $1=START $2=text and $3=END or various other permutations by adding/removing ()s or ?:s.
That way if you are using it to do search and replace, you can do, something like BEGIN$1FINISH. So, if you started with:
abcSTARTdefSTARTghiENDjkl
you would get ghi as capture group 1, and replacing with BEGIN$1FINISH would give you the following:
abcSTARTdefBEGINghiFINISHjkl
which would allow you to change your START/END tokens only when paired properly.
Each (x) is a group, but I have put (?:x) for each of the ones except the middle which marks it as a non-capturing group; the only one I left without a ?: was the middle; however, you could also conceivably capture the BEGIN/END tokens as well if you wanted to move them around or what-have-you.
See the Java regex documentation for full details on Java regexes.
Hello I am trying to use regex to make sure the user has entered at minimum three dot points I think i am close but at the moment my expression will return unexpected results.
Here is my expression as of 30/01/17
/(•([\s]*[\w]+|[\.\,]*)*|\n){3,}/g
and here is the text snippet i am testing;
blahblahblahblahblahblahblah
blahblahblahblahblahblah
blahblahblahblahblahblah.
• blahblahblahblahblahblah.
•blahblahblahblahblahblah.
blahblahblahblahblahblah.
.•blahblah, blahblahblahblah.
NOTE: I put the full stop in place in the third dot point as it is the easiest way to trigger the unexpected result.
Thanks in advance for any feedback.
You can look for non dots [^.] then a dot [.] followed by non dots [^.] three times:
/(?:[^.]*[.][^.]){3,}/
Demo
You can use the same procedure of a • if that is the character you are referring to.
Use a look ahead:
^(?=(.*\.){3}).*
You can use this regex ^ *•.*$, and if it finds three matches, then you have three lines starting will a bullet point. You have to use the multiline (m) flag, so ^ and $ also match start and end of a line respectively. I can show you code if you tell me what language your are using.
If you only want to make sure the text contains three bullet points (ex: this ••• can work), then don't use regex at all, your language most likely have a function to count matches of a character in a string.
Don't forget to upvote! ;)
I've the following RegExp to find the URIs listed above:
"^w{3}\.[\S\-\n|\S]+[^\s.!?,():]+$"
URLs to find:
www.example.org
www.example-example.org
www.example-example.org/product
You'll find it at www.example-
example.org/product.
www.example.org
You'll find it there.
Number 1, 2 and 3 will be found, but 4. delivers "www.example-" as URI.
When there is no point at the end of 4. it would deliver it correct.
EDIT: With deleting ^ and $ only number 5 is not working.
Does anyone can help here?
Your pattern
^w{3}\.[\S\-\n|\S]+[^\s.!?,():]+$
can be simplified to
^w{3}\.[\S\n]+[^\s.!?,():]$
[\S\-\n|\S] this is a character class, no OR possible, no repetition needed, - is included in \S. So [\S\n] is doing the same.
[^\s.!?,():]+ because you match every non whitespace with the expression before this one, here the + is not needed. I assume you just want your pattern not to end with one of the characters from the class.
See your pattern on Regexr (I added \r to your first class, because the line breaks there needs it)
This is a very useful tool to test regexes
I think your problem is that you want to allow line breaks in the link. How do you want to handle this? How do you want to distinguish when the line ends with a link if the word in the next line is just a word or part of the link. I think this is not possible!
The problem is the '^\s' in the second squared bracketed part. Depending on your programming language, '\s' might match the new line. So, you are telling it to match anything that is not a whitespace and it finds a whitespace (new line).
However, this should only be one of your issues. Your regex uses the '^' and '$' characters which mean start and end of line respectively. Try this URL example:
hello from www.example.org
Did it match? I think it will not.
I've been looking around and could not make this happen. I am not totally noob.
I need to get text delimited by (including) START and END that doesn't contain START. Basically I can't find a way to negate a whole word without using advanced stuff.
Example string:
abcSTARTabcSTARTabcENDabc
The expected result:
STARTabcEND
Not good:
STARTabcSTARTabcEND
I can't use backward search stuff. I am testing my regex here: www.regextester.com
Thanks for any advice.
Try this
START(?!.*START).*?END
See it here online on Regexr
(?!.*START) is a negative lookahead. It ensures that the word "START" is not following
.*? is a non greedy match of all characters till the next "END". Its needed, because the negative lookahead is just looking ahead and not capturing anything (zero length assertion)
Update:
I thought a bit more, the solution above is matching till the first "END". If this is not wanted (because you are excluding START from the content) then use the greedy version
START(?!.*START).*END
this will match till the last "END".
START(?:(?!START).)*END
will work with any number of START...END pairs. To demonstrate in Python:
>>> import re
>>> a = "abcSTARTdefENDghiSTARTjlkENDopqSTARTrstSTARTuvwENDxyz"
>>> re.findall(r"START(?:(?!START).)*END", a)
['STARTdefEND', 'STARTjlkEND', 'STARTuvwEND']
If you only care for the content between START and END, use this:
(?<=START)(?:(?!START).)*(?=END)
See it here:
>>> re.findall(r"(?<=START)(?:(?!START).)*(?=END)", a)
['def', 'jlk', 'uvw']
The really pedestrian solution would be START(([^S]|S*S[^ST]|ST[^A]|STA[^R]|STAR[^T])*(S(T(AR?)?)?)?)END. Modern regex flavors have negative assertions which do this more elegantly, but I interpret your comment about "backwards search" to perhaps mean you cannot or don't want to use this feature.
Update: Just for completeness, note that the above is greedy with respect to the end delimiter. To only capture the shortest possible string, extend the negation to also cover the end delimiter -- START(([^ES]|E*E[^ENS]|EN[^DS]|S*S[^STE]|ST[^AE]|STA[^RE]|STAR[^TE])*(S(T(AR?)?)?|EN?)?)END. This risks to exceed the torture threshold in most cultures, though.
Bug fix: A previous version of this answer had a bug, in that SSTART could be part of the match (the second S would match [^T], etc). I fixed this but by the addition of S in [^ST] and adding S* before the non-optional S to allow for arbitrary repetitions of S otherwise.
May I suggest a possible improvement on the solution of Tim Pietzcker?
It seems to me that START(?:(?!START).)*?END is better in order to only catch a START immediately followed by an END without any START or END in between. I am using .NET and Tim's solution would match also something like START END END. At least in my personal case this is not wanted.
[EDIT: I have left this post for the information on capture groups but the main solution I gave was not correct.
(?:START)((?:[^S]|S[^T]|ST[^A]|STA[^R]|STAR[^T])*)(?:END)
as pointed out in the comments would not work; I was forgetting that the ignored characters could not be dropped and thus you would need something such as ...|STA(?![^R])| to still allow that character to be part of END, thus failing on something such as STARTSTAEND; so it's clearly a better choice; the following should show the proper way to use the capture groups...]
The answer given using the 'zero-width negative lookahead' operator "?!", with capture groups, is: (?:START)((?!.*START).*)(?:END) which captures the inner text using $1 for the replace. If you want to have the START and END tags captured you could do (START)((?!.*START).*)(END) which gives $1=START $2=text and $3=END or various other permutations by adding/removing ()s or ?:s.
That way if you are using it to do search and replace, you can do, something like BEGIN$1FINISH. So, if you started with:
abcSTARTdefSTARTghiENDjkl
you would get ghi as capture group 1, and replacing with BEGIN$1FINISH would give you the following:
abcSTARTdefBEGINghiFINISHjkl
which would allow you to change your START/END tokens only when paired properly.
Each (x) is a group, but I have put (?:x) for each of the ones except the middle which marks it as a non-capturing group; the only one I left without a ?: was the middle; however, you could also conceivably capture the BEGIN/END tokens as well if you wanted to move them around or what-have-you.
See the Java regex documentation for full details on Java regexes.
I have a feed in Yahoo Pipes and want to match everything after a question mark.
So far I've figured out how to match the question mark using..
\?
Now just to match everything that is after/follows the question mark.
\?(.*)
You want the content of the first capture group.
Try this:
\?(.*)
The parentheses are a capturing group that you can use to extract the part of the string you are interested in.
If the string can contain new lines you may have to use the "dot all" modifier to allow the dot to match the new line character. Whether or not you have to do this, and how to do this, depends on the language you are using. It appears that you forgot to mention the programming language you are using in your question.
Another alternative that you can use if your language supports fixed width lookbehind assertions is:
(?<=\?).*
With the positive lookbehind technique:
(?<=\?).*
(We're searching for a text preceded by a question mark here)
Input: derpderp?mystring blahbeh
Output: mystring blahbeh
Example
Basically the ?<= is a group construct, that requires the escaped question-mark, before any match can be made.
They perform really well, but not all implementations support them.
\?(.*)$
If you want to match all chars after "?" you can use a group to match any char, and you'd better use the "$" sign to indicate the end of line.
?(.*\n)+
With this you can get everything Even a new line
Check out this site: http://rubular.com/ Basically the site allows you to enter some example text (what you would be looking for on your site) and then as you build the regular expression it will highlight what is being matched in real time.
str.replace(/^.+?\"|^.|\".+/, '');
This is sometimes bad to use when you wanna select what else to remove between "" and you cannot use it more than twice in one string. All it does is select whatever is not in between "" and replace it with nothing.
Even for me it is a bit confusing, but ill try to explain it. ^.+? (not anything OPTIONAL) till first " then | Or/stop (still researching what it really means) till/at ^. has selected nothing until before the 2nd " using (| stop/at). And select all that comes after with .+.