I am really struggling with RegEx. I want my RegEx (if possible) to do 2 things:
1- Validate that the whole string respects the format NAME_STKBYGRP.CSV
2- Extract the NAME substring if match
Examples:
TEST_STKBYGRP.CSV -> TEST
other_stkbygrp.csv -> other
test_wrong.csv -> ""
Here is what I tried so far
string input = "NAME_STKBYGRP.CSV";
Regex regex = new Regex("([A-Z])*_STKBYGRP.CSV", RegexOptions.IgnoreCase);
string s = regex.Match(input).Value;
It does return "" if it doesn't match but return the whole input if it matches.
You need to read regex.Match(input).Groups[1].Value if you only want the value of the first group.
You should also add a ^ and $ at the start and end of your regex if you want to rule out strings like evilnumber12345_NAME_STKBYGRP.CSVevilsuffix.
Edit: adv12 also has a good point about the location of the * - it should be inside the parentheses.
First off, your * should be inside the parentheses. Otherwise, you'll capture several single-character groups. Then, use Match.Groups[1] to get just the characters matched by the portion of the regex in the parentheses.
Related
I am trying to use Regex to count the number of times a certain string appears in another comma-separated string.
I am using Regex.Matches(comma-separated string, certain string).Count to grab the number. The only issue I have is that I want it to simply count as a match if it lines up at the start of the string.
For instance, if I have the comma separated string
string comma_separated = "dog,cat,bird,blackdog,dog(1)";
and want to see how many times the search string matches with the contents of the comma-separated string
string search = "dog";
I use:
int count = Regex.Matches(comma_separated, search).Count;
I would expect it to be 2 since it matches up with
"dog,cat,bird,blackdog,dog(1)",
however it returns a 3 since it is also matching up with the dog part of blackdog.
Is there any way I can get it to only count as a match when it recognizes a match starting at the start of the string? Or am I just using Regex incorrectly?
As noted in the comments, a regex may not be the most logical way for you to achieve your desired result. However, if you would like to use a regex to find your matches, something like this would provide your desired result
(?<=,|^)dog
This will perform a "positive lookbehind" to ensure that the word "dog" is preceded by either a comma or is at the start of the string you are searching.
More info available on lookarounds in Regex here: https://www.regular-expressions.info/lookaround.html
string comma_separated = "dog,cat,bird,blackdog,dog(1)";
int count = Regex.Matches(comma_separated, string.Format(#"\b{0}\b", Regex.Escape("dog")), RegexOptions.IgnoreCase).Count;
By appending the \b to either side of the text you can find the "EXACT" match within the text.
Try using this pattern: search = #"\bdog";. \b matches word boundary.
I am trying to replace some content using regular expression and not able to do it, can you please have a look..
My Input: <Tag>E2iamjunkblabla</Tag>
Expected Output: <Tag>E2done</Tag>
I am trying this:
string input = "<Tag>E2iamjunkblabla</Tag>";
string output= System.Text.RegularExpressions.Regex.Replace(input, "<Tag>E2*</Tag>", "<Tag>E2done</Tag>");
What am I doing wrong? Also is there any way to retain first 3 characters(numbers or alphbets) after E2?
I mean the output should be
<Tag>E2iam</Tag>
Sounds like you want this:
string input = "<Tag>E2iamjunkblabla</Tag>";
string output = System.Text.RegularExpressions.Regex.Replace(input, "<Tag>E2(...).*</Tag>", #"<Tag>E2$1done</Tag>");
To break it down:
The match:
Match <Tag> then match E2 then match any character 3 times (...) (the parenthesis mean to store that capture in a group), then match any character zero or more times .* followed by the literal </Tag>
The replace:
Replace the value with <Tag>E2 then the value of capture group 1 $1 then the literal done</Tag>
Let me know if you have issues - and read up on regex! (oh and there are probably a load of ways to do this, this is just one of them)
I have a regex expression which searches for strings using a Prefix and a Suffix. In it's simplest form \$\$\w+\$\$ will find $$My_Name$$ (in this case the Prefix and Suffix are both equal to $$) Another example would be \[\#\w+\#\] to match [#My_Name#].
The Prefix and Suffix will always be a specific string of 0 to n characters which I can always safely escape for a direct character match.
I extract the Matches in my C# code so I can work with them but obviously my match contains $$My_Name$$ but what I want is to simply get the inner string between the Suffix and Prefix: My_Name.
How do I exclude the Prefix and Suffix from the result?
Change your REGEX to \$\$(\w+)\$\$ and use $1 to get the matching (inner) string.
For example
string pattern = #"\$\$(\w+)\$\$";
string input = "$$My_Name$$";
Regex rgx = new Regex(pattern);
Match result = rgx.Match(input);
Console.WriteLine(result.Groups[1]);
Outputs: "My Name"
P.S - There's no need to use explicitly typed local variables, but I just wanted the types to be clear.
You can group your w+ into a group like this (w+) then when you retrieve the matched string you might be able to ask for that subgroup.
I do not know if I am wrong (but you didn't provided any code whatsoever) but I think this is how it is done: .Groups[1].Value on the the result of Regex.Match.
How about the regex below. It works by capturing the first character into a named group then capturing any repeats into a named group called first group which it then uses to match the end of the string. It will work with any number of repeated character so long as they repeated at the end of the word.
'(?<first_group>(?<first_char>.)\k<first_char>+)(?<word>\w+)\k<first_group>+'
You just need to then extract the capture group named word like so:
String sample = "$$My_Name$$";
Regex regex = new Regex("(?<first_group>(?<first_char>.)\k<first_char>+)(?<word>\w+)\k<first_group>+");
Match match = regex.Match(sample);
if (match.Success)
{
Console.WriteLine(match.Groups["word"].Value);
}
You can use named group like this:
(\$\$)(?<group1>.+?)\1 -- pattern 1 (first case)
\[(#)(?<group2>.+?)\1\] -- pattern 2 (second case)
or combined representation would be:
(\$\$)(?<group1>.+?)\1|\[(#)(?<group2>.+?)\3\]
I would suggest you to use .+? it will help you to match any character other than your prefix/suffix.
Live Demo
Greetings beloved comrades.
I cannot figure out how to accomplish the following via a regex.
I need to take this format number 201101234 and transform it to 11-0123401, where digits 3 and 4 become the digits to the left of the dash, and the remaining five digits are inserted to the right of the dash, followed by a hardcoded 01.
I've tried http://gskinner.com/RegExr, but the syntax just defeats me.
This answer, Equivalent of Substring as a RegularExpression, sounds promising, but I can't get it to parse correctly.
I can create a SQL function to accomplish this, but I'd rather not hammer my server in order to reformat some strings.
Thanks in advance.
You can try this:
var input = "201101234";
var output = Regex.Replace(input, #"^\d{2}(\d{2})(\d{5})$", "${1}-${2}01");
Console.WriteLine(output); // 11-0123401
This will match:
two digits, followed by
two digits captured as group 1, followed by
five digits captured as group 2
And return a string which replaces that matched text with
group 1, followed by
a literal hyphen, followed by
group 2, followed by
a literal 01.
The start and end anchors ( ^ / $ ) ensure that if the input string does not exactly match this pattern, it will simply return the original string.
If you can use custom C# scripts, you may want to use Substring instead:
string newStr = string.Format("{0}-{1}01", old.Substring(2,2), old.Substring(4));
I don't think you really need a regex here. Substring would be better. But still if you want regex only, you can use this:
string newString = Regex.Replace(input, #"^\d{2}(\d{2})(\d+)$", "$1-${2}01");
Explanation:
^\d{2} // Match first 2 digits. Will be ignored
(\d{2}) // Match next 2 digits. Capture it in group 1
(\d+)$ // Match rest of the digits. Capture it in group 2
Now, the required digits, are in group 1 and 2, which you use in the replacement string.
Do you even SQL? Pull some levers and stuff.
Ok sorry this might seem like a dumb question but I cannot figure this thing out :
I am trying to parse a string and simply want to check whether it only contains the following characters : '0123456789dD+ '
I have tried many things but just can't get to figure out the right regex to use!
Regex oReg = new Regex(#"[\d dD+]+");
oReg.IsMatch("e4");
will return true even though e is not allowed...
I've tried many strings, including Regex("[1234567890 dD+]+")...
It always works on Regex Pal but not in C#...
Please advise and again i apologize this seems like a very silly question
Try this:
#"^[0-9dD+ ]+$"
The ^ and $ at the beginning and end signify the beginning and end of the input string respectively. Thus between the beginning and then end only the stated characters are allowed. In your example, the regex matches if the string contains one of the characters even if it contains other characters as well.
#comments: Thanks, I fixed the missing + and space.
Oops, you forgot the boundaries, try:
Regex oReg = new Regex(#"^[0-9dD +]+$");
oReg.IsMatch("e4");
^ matches the begining of the text stream, $ matches the end.
It is matching the 4; you need ^ and $ to terminate the regex if you want a full match for the entire string - i.e.
Regex re = new Regex(#"^[\d dD+]+$");
Console.WriteLine(re.IsMatch("e4"));
Console.WriteLine(re.IsMatch("4"));
This is because regular expressions can also match parts of the input, in this case it just matches the "4" of "e4". If you want to match a whole line, you have to surround the regex with "^" (matches line start) and "$" (matches line end).
So to make your example work, you have to write is as follows:
Regex oReg = new Regex(#"^[\d dD+]+$");
oReg.IsMatch("e4");
I believe it's returning True because it's finding the 4. Nothing in the regex excludes the letter e from the results.
Another option is to invert everything, so it matches on characters you don't want to allow:
Regex oReg = new Regex(#"[^0-9dD+]");
!oReg.IsMatch("e4");