I have below sample string
abc,com;def,med;ghi,com;jkl,med
I have to grep the string which is coming before keyword ",com" (all occurrences)
Final result which is I am looking for is something like -
abc,ghi
I have tried below positive lookahead regex -
[\s\S]*?(?=com)
But this is only fetching abc, not the ghi.
What modification do I need to make in above regex?
Using a character class [\s\S] can match any character and will also match the , and ;
What you can do is match non whitespace characters except for , and ; using a negated character class and that way you don't have to make it non greedy as well.
Then assert the ,com to the right (followed by a word boundary to prevent a partial word match)
Instead of using a lookahead, you might also use a capture group:
([^\s,;]+),com\b
See a regex demo with the capture group values.
Related
I have the following string
abc123+InterestingValue+def456
I want to get the InterestingValue only, I am using this regex
\+.*\+
but the output it still includes the + characters
Is there a way to search for a string between the + characters, then search again for anything that is not a + character?
Use lookarounds.
(?<=\+)[^+]*(?=\+)
DEMO
You can use a positive lookahead and a positive lookbehind (more info about these here). Basically, a positive lookbehind tells the engine "this match has to come before the next match", and a positive lookahead tells the engine "this has to come after the previous match". Neither of them actually match the pattern they're looking for though.
A positive lookbehind is a group beginning with ?<= and a positive lookahead is a group beginning with ?=. Adding these to your existing expression would look like this:
(?<=\+).*(?=\+)
regex101
If it should be the first match, you can use a capture group with an anchor:
^[^+]*\+([^+]+)\+
^ Start of string
[^+]* Optionally match any char except + using a negated character class
\+ Match literally
([^+]+) Capture group 1, match 1+ chars other than +
\+ Match literally
Regex demo
I am having a hard time coming up with a regex to match a specific case:
This can be matched:
any-dashed-strings
this-can-be-matched-even-though-its-big
This cannot be matched:
strings starting with elem- or asdf- or a single -
elem-this-cannot-be-matched
asdf-this-cannot-be-matched
-
So far what I came up with is:
/\b(?!elem-|asdf-)([\w\-]+)\b/
But I keep matching a single - and the whole -this-cannot-be-matched suffix. I cannot figure it out how to not only ignore a character present inside the matching character class conditionally, and not matching anything else if a suffix is found
I am currently working with the Oniguruma engine (Ruby 1.9+/PHP multi-byte string module).
If possible, please elaborate on the solution. Thanks a lot!
If a lookbehind is supported, you can assert a whitespace boundary to the left, and make the alternation for both words without the hyphen optional.
(?<!\S)(?!(?:elem|asdf)?-)[\w-]+\b
Explanation
(?<!\S) Assert a whitespace boundary to the left
(?! Negative lookahead, assert the directly to the right is not
(?:elem|asdf)?- Optionally match elem or asdf followed by -
) Close the lookahead
[\w-]+ Match 1+ word chars or -
\b A word boundary
See a regex demo.
Or a version with a capture group and without a lookbehind:
(?:\s|^)(?!(?:elem|asdf)?-)([\w-]+)\b
See another regex demo.
So far I tried this regex but no luck.
([^=;]+=[^=;]+(;(?!$)|$))+
Valid Strings:
something=value1;another=value2
something=value1 ; anothe=value2
Invalid Strings:
something=value1 ;;;name=test
some=value=3;key=val
somekey=somevalue;
You might use an optional repeating group to get the matches.
If you don't want to cross newline boundaries, you might add \n or \r\n to the negated character class.
^[^=;\n]+=[^=;\n]+(?:;[^=;\n]+=[^=;\n]+)*$
Explanation
^ Start of string
[^=;\n]+=[^=;\n]+ Match the key and value using a negated character class
(?: Non capture group
;[^=;\n]+=[^=;\n]+ Match a comma followed by the same pattern
)* Close group and repeat 0+ times
$ End string
Regex demo
I want to match
abc_def_ghi,
abc_abc_ghi,
abc_a2a_ghi,
abc_999_ghi
but not abc_xxx_ghi (with xxx in center).
I came up to manually consuming look ahead (abc_(?!xxx)..._ghi), but I wonder is there any other way without manually specifying number of characters to skip.
Original qustion was with numbers, updated for strings case.
If you don't want to specify exactly how many characters to skip, perhaps you could use a quantifier like + in the negative lookahead and use a negated character class to match not an underscore.
\babc_(?!x+_)[^_]+_ghi\b
Explanation
\babc_ Word boundary, match abc_
(?! Negative lookahead, assert what is directly on the right is not
x+_ Match 1+ times x followed by an underscore
) Close lookahead
[^_]+_ Negated character class, match 1+ times any char except _
ghi\b Match ghi and word boundary
Regex demo
You can use this
123_(?:(?!000)\d){3}_789
Regex demo
If you don't wish to use look-arounds, this expression might be an option:
(?:abc_xxx_ghi)|(abc_.{3}_ghi)
Other than that I can't think of anything else.
DEMO
There are a thousand regular expression questions on SO, so I apologize if this is already covered. I did look first.
I have string:
Name Subname 11X22 88X620 AB33(20) YA5619 77,66
I need to capture this string: YA5619
What I am doing is just finding AB33(20) and after this I am capturing until first white space. But AB33(20) can be AB-33(20) or AB33(-20) or AB33(-1).
My preg_match regex is: (?<=\bAB\d{2}\(\d{2}\)\s).+?(?=\s)
Why I am getting error when I change from \d{2} to \d+?
For final result I was thinking this regix will work but no:
(?<=\bAB-?\d+\(-?\d+\)\s).+?(?=\s)
Any ideas what I am doing wrong?
With most regex flavors, lookbehind needs to evaluate to a fixed-length sequence, so you can't use variable quantifiers like * or + or even {1,2}.
Instead of using lookaround, you can simply match your marker pattern and then forget it with \K.
AB-?\d+(?:\(-?\d+\))? \K[^ ]+
demo: https://regex101.com/r/8XXngH/1
It depends on the language. If it is in .NET for example, it matches due to the various length in the lookbehind.
Another solution might be to use a character class and add the character you would allow to match. Then match a whitespace character and capture in a group matching \S+ which matches 1+ times not a whitespace character.
\bAB[()\d-]+\s\K\S+
Explanation
\bAB Match literally prepended with word boundary to prevent AB being part of a larger match.
[()\d-]+ Match 1+ times any of the listed character in the character class
\s Match a whitespace char (or \s+ to match 1 or more)
\K Reset the starting point of the reported match( Forget what was matched)
\S+ Match in a group 1+ times not a whitespace character
Regex demo | Php demo