How can I match the the pattern any number followed by h or t or l like 1h , 126h or 1268h but not 1.1h 12.6h or 12.68h in a given paragraph.
I am writing a application that can replace 1h to 100 or 1268h to 126800 so that instead of typing 00 a person can simply place h with a number but due to some error it is also matching decimal numbers, too.
Pattern that I wrote is (\d+)(h|t|l)
You could use a whitespace boundary to the left (?<!\S) if a positive lookbehind is supported or anchors to match the whole line.
The alternation can be written as a character class [htl]
(?<!\S)(\d+)([htl])
(?<!\S) Positive lookbehind, assert what is on the left is not a non whitespace char
(\d+) Capture group 1, match 1+ digits
([htl]) Capture group 2, match either h torl`
Regex demo
Using anchors to match the whole line
^(\d+)([htl])$
Regex demo
Without a lookaround, you could match either a whitespace char or the start of the string (?:\s|^) for example:
(?:\s|^)(\d+)([htl])
Regex demo
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 need to match a character to split a big string, let's say -, but not if it's between two digits
In a-b it should match -
In a-4 it should match -
In 3-a it should match -
In 3-4 it should not match
I've tried negative lookahead and lookbehind, but I've only been able to come up with this (?<=\D)-(?=\D)|(?<=\d)-(?=\D)|(?<=\D)-(?=\d)
Is there a simpler way to specify this pattern?
Edit: using regex conditionals I think I can use (?(?<=\D)-|-(?=\D))
The following will work for this scenario. Be sure that your Regex flavor of choice has conditionals, otherwise this will not work:
-(?(?=\d)(?<=\D-))
- // match a dash
(? // If
(?=\d) // the next character is a digit
(?<= // then start a lookbehind (assert preceding characters are)
\D- // a non-digit then the dash we matched
) // end lookbehind
) // end conditional
With nothing as the substitution, as the dash is the only character captured.
Another option is to use an alternation to match a - when on the left is not a digit or match a - when on the right is not a digit:
(?<!\d)-|-(?!\d)
(?<!\d)- Negative lookbehind, assert what is on the left is not a digit and match -
| or
-(?!\d) Match - and assert what is on the right is not a digit using a negative lookahead
Regex demo
I have the following template :
1251 Left Random Text I want to fill
It can go through multiple lines
As you can see
9841 Right Again we see a lot of random text with 3115 numbers
And this also goes
To multiple lines
0121 Right
5151 Right This one is just one line
I was wrong
9731 Left This one is just a line
5123 NA Instruction 5151 was wrong
4113 Right Instr 9841 was correct
We checked
I want to have 3 groups:
1251
Left
Random Text I want to fill
It can go through multiple lines
As you can see
I'm using
(\d+)\s(\w+)\s(.*)
but it stops at the current line only (so I get only Random Text I want to fill in group 3, although I want including As you can see)
If I'm using Single line flag I get only 1 match for each group, group 3 almost being all
Here is live : https://regex101.com/r/W3x0mH/4
You could use a repeating group matching all the lines while asserting that the next line does not start wit 1+ digits followed by Left or Right:
(\d+)\s(\w+)\s(.*(?:\r?\n(?!\d).*)*)
Explanation
(\d+)\s(\w+)\s Match the first 2 groups
(Third capturing group
.* Match 0+ times any char except a newline
(?: Non capturing group
\r?\n(?!\d).* Match newline, assert what is on the right is not a digit
)* Close non capturing group and repeat 0+ times
) Close capturing group
Regex demo
You may use this regex with a lookahead:
^(\d+)\s(\w+)\s(.*?)(?=\n\d|\z)
with DOTALL and MULTILINE modifiers.
Updated Regex Demo
RegEx Details:
^: Line start
(\d+): Match and capture 1+ digits in group #1
\s: match a whitespace
(\w+): Match and capture 1+ word characters in group #2
\s: match a whitespace
(.*?): Match 0 or more of any character (non-greedy) provided next lookahead assertion is satiSfied
(?=\n\d|\z): Lookahead assertion to assert that we have a newline followed by a digit or there is end of input
Faster Regex:
If you are using this regex on a long string then you should also keep overall performance in mind as a regex with DOTALL modifier will tend to get slow on a large size text. For that I suggest using this regex that doesn't need DOTALL modifier:
^(\d+)\s(\w+)\s(.*(?:\n.*)*?)(?=\n\d|\z)
RegEx Demo 2
On regex101 demo this regex takes just 181 steps as compared to first one that takes 1300 steps.
For the third group, repeat any character while using negative lookahead for ^\d, which would indicate the start of a new match:
(\d+)\s(\w+)\s((?:(?!^\d)[\s\S])*)
https://regex101.com/r/W3x0mH/5
You may try with this regex:
^(\d+)\s+(\w+)\s+(.*?)(?=^\d|\z)
^(\d+)\s+ , ^\d+ Line begins with numbers followed by one or more whitespace character \s+
(\w+)\s+ where \w+ one or more characters (left,right,na or something else) followed by one or more whitespace \w+
(.*?) matches everything until it finds a line beginning with number or \z end of string.
I think it fits your requirement....
Regex101
I'm trying to match: 0 or more numbers followed by a dot followed by ( (0 or more numbers) but not (if followed by a d,D, or _))
Some examples and what should match/not:
match:
['1.0','1.','0.1','.1','1.2345']
not match:
['1d2','1.2d3','1._dp','1.0_dp','1.123165d0','1.132_dp','1D5','1.2356D6']
Currently i have:
"([0-9]*\.)([0-9]*(?!(d|D|_)))"
Which correctly matches everything in the match list. But for those in the things it should not match it incorrectly matches on:
['1.2d3','1.0_dp','1.123165d0','1.132_dp','1.2356D6']
and correctly does not match on:
['1d2','1._dp','1D5']
So it appears i have problem with the ([0-9]*(?!(d|D|_)) part which is trying to not match if there is a d|D|_ after the dot (with zero or more numbers in-between). Any suggestions?
Instead of using a negative lookahead, you might use a negated character class to match any character that is not in the character class.
If you only want to match word characters without the dD_ or a whitespace char you could use [^\W_Dd\s].
You might also remove the \W and \s to match all except dD_
^[0-9]*\.[^\W_Dd\s]*$
Explanation
^ Start of string
[0-9]*\. Match 0+ times a digit 0-9 followed by a dot
[^\W_Dd\s]* Negated character class, match 0+ times a word character without _ D d or whitespace char
$ End of string
Regex demo
If you don't want to use anchors to assert the start and the end of the string you could also use lookarounds to assert what is on the left and right is not a non whitspace char:
(?<!\S)[0-9]*\.[^\W_Dd\s]*(?!\S)
Regex demo
\d*[.](?!.*[_Dd]).* is what you are looking for:
I need to find words in a string that start with number(i.e digit)
In following string:
1st 2nd 3rd a56b 5th 6th ***7th
The words 1st 2nd 3rd 5th 6th should be returned.
I tried with the regex:
(\b[^ a-zA-Z ^ *]+(th|rd|st|nd))+
But this regex returns the words not starting with alphabets but can't handle the cases when word starts with special characters.
For the current string, you may use a pattern like
(?<!\S)\d+(?:th|rd|st|nd)\b
See the regex demo
The pattern matches:
(?<!\S) - a location at the start of a string or after a whitespace
\d+ - 1 or more digits
(?:th|rd|st|nd) - one of the four alternatives
\b - a word boundary.
If you plan to match any 0+ non-whitespace chars after a digit that is preceded with a whitespace or is at the start of a string, use
(?<!\S)\d\S*
where \S* will match any 0+ non-whitespace chars.
See this regex demo.
NOTE: In case the lookbehind is not supported, replace (?<!\S) with (?:^|\s) and also wrap the rest of the pattern with a capturing group to access the latter later:
(?:^|\s)(\d\S*)
and the value will be in Group 1.
To get word which is starting with number/digit and ending with th/st/nd/rd you can try this.
((?<!\S)(\d+)(th|rd|nd|st))
(?<!\S) detects the word's starting position
\d+ matches 1 or more digits
th|rd|st|nd matches one among those 4.
You can check it here