c# regex extracting substrings from a string [duplicate] - c#

This question already has answers here:
My regex is matching too much. How do I make it stop? [duplicate]
(5 answers)
Closed 4 years ago.
I need to get all substrings that are placed between 2 signs.
For example substrings placed between ] and [:
abcabc]substrings[kkkkkkk]iwant[12345]tohave[!##$%]
and I get: substrings iwant tohave
I tried (?<=\])(.*)(?=\[) but it returns substrings[kkkkkkk]iwant[12345]tohave.

Your regex would need to be (?<=\])(.*?)(?=\[).
Note the added ? sign to match as few as possible.
Then you have to combine the (at the moment) three matches with spaces and you will get the output you want!

Make it non greedy .*? or else it would match until the last [
You don't need the capturing group if you want to get the matches only:
(?<=\]).*?(?=\[)
Test

Related

Need Regular expression for the following [duplicate]

This question already has answers here:
Regular expression to validate numbers separated by commas or dashes [closed]
(2 answers)
Closed 2 years ago.
I have to write the Regex expression which accepts - and only numbers either single four digit number or two 4 digit numbers seperated by hyphen as shown below
2751, 2759-2764, 2766-2774, 2776-2777, 2890-2897
3945-3974, 3979, 3984-3999
I have used this Regex ^[0-9_,]+ but this line Regex.IsMatch(line, #"^[0-9_,]+$") returns false.
Regards,
Nagasree
The pattern that you tried is not matching as there is no hyphen or space in the character class. But when you would add those, the pattern still does not take any format into account.
You could match 4 digits with optional hyphen and 4 digits part. Then repeat that preceded by a space:
^[0-9]{4}(?:-[0-9]{4})?(?:, [0-9]{4}(?:-[0-9]{4})?)*$
Regex demo
var s = "2751, 2759-2764, 2766-2774, 2776-2777, 2890-2897";
Console.WriteLine(Regex.IsMatch(s, #"^[0-9]{4}(?:-[0-9]{4})?(?:, [0-9]{4}(?:-[0-9]{4})?)*$"));
Output
True

How to get all possible Regex Matches [duplicate]

This question already has answers here:
C# Code to generate strings that match a regex [closed]
(4 answers)
Closed 3 years ago.
Based off a regex string I would like to get a list of all the possible strings that would match the regex.
Example:
Given a regex string like...
^(en/|)resources/case(-| )studies/
I want to get a list of all the possible strings that would match the regex expression. Like...
^en/resources/case-studies/
or
^/resources/case-studies/
or
^en/resources/case studies/
or
^/resources/case studies/
Thank you
Note that in regex ^ denotes the beginning of the line. You must escape it
Try
\^(en)?/resources/case(-|\s)studies/
explanation:
\^ is ^ escaped.
(en)? is optionally en, where ? means zero or one times.
/resources/case the text as is.
(-|\s) minus sign or white space.
studies/ the text as is.
See: https://dotnetfiddle.net/PO4wKV

Regex expression to verify that a string only contains letters, numbers, underscores and dashes [duplicate]

This question already has answers here:
Reference - What does this regex mean?
(1 answer)
What do ^ and $ mean in a regular expression?
(2 answers)
Closed 3 years ago.
I've already read this here and I still have got some questions. I will be very grateful if you can help me to solve them. I'm trying to compose a RegEx to verify that a string contains only letters, numbers, underscores and hyphens. Firstly, when I tried to do it (without Google-search) I did this #"[A-Za-z0-9_-]". After I made some research I found that it should be #"^[a-zA-Z0-9_-]$" where:
^ asserts position at start of a line
$ asserts position at the end of a line
My question is why we should insert these symbols? And my other question is why the string "jeffbutt" (with yellow in the screenshot) doesn't match?

Not terminated set of [] in regex (C#) [duplicate]

This question already has answers here:
Regex Match all characters between two strings
(16 answers)
Closed 5 years ago.
I'm trying to parse a text looking for data inside this pattern:
{{([^]+)}}
i.e. any sequence of characters between {{ and }} .
But, when I try to build a Regex object:
Regex _regex = new Regex("{{([^]+)}}", RegexOptions.Compiled);
I got this error:
analysis of "{{([^]+)}}" - Set of [] not terminated....
whatever it means...
Someone has an hint?
The purpose of [^...] is to negate character classes present in the specified list. After the ^ symbol, in order to define a correct regular expression, you should include a set of characters to exclude like, for example [^a]+ (this matches one or more characters that don't include the literal a).
The regex you are attempting to define is probably:
{{\s*([\w]+)\s*}}
Visit this link for trying a working demo.
This is because [^] is not a valid regex, because you need to specify at least one symbol that you wish to exclude.
In order to capture the string up to the closing }} change the expression to this:
{{((?:[^}]|}[^}])*)}}
Demo.

How to make a "minimal match" Regex search in C#? [duplicate]

This question already has answers here:
My regex is matching too much. How do I make it stop? [duplicate]
(5 answers)
Closed 3 years ago.
Let's say I have a multi-line string like this:
STARTFRUIT
banana
ENDFRUIT
STARTFRUIT
avocado
ENDFRUIT
STARTVEGGIE
rhubarb
ENDVEGGIE
STARTFRUIT
lime
ENDFRUIT
I want to search for all fruit, no veggies. I try this:
MatchCollection myMatches = Regex.Matches(tbBlob.Text, "STARTFRUIT.*ENDFRUIT", RegexOptions.Singleline);
foreach (var myMatch in myMatches)
{
Forms.MessageBox.Show(String.Format("Match: {0}", myMatch), "Match", Forms.MessageBoxButtons.OK, Forms.MessageBoxIcon.Information);
}
The problem is, instead of returning me an array of three matches, it gives me a big match encompassing the first STARTFRUIT at the beginning and the last ENDFRUIT at the end. Is there a way to "minimalize" the match search? I don't see any help in RegexOptions.
Use a non-greedy modifier (a question mark) after the quantifier:
"STARTFRUIT.*?ENDFRUIT"
^
add this
Note that the question-mark here has a different meaning here than when it is used as a quantifier, where it means "match zero or one".

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