We Keep Coding

RegEx string between N and (N+1)th Occurance

I am attempting to find nth occurrence of sub string between two special characters. For example.
one|two|three|four|five
Say, I am looking to find string between (n and n+1 th) 2nd and 3rd Occurrence of '|' character, which turns out to be 'three'.I want to do it using RegEx. Could someone guide me ?
My Current Attempt is as follows.
string subtext = "zero|one|two|three|four";
Regex r = new Regex(#"(?:([^|]*)|){3}");
var m = r.Match(subtext).Value;

If you have full access to C# code, you should consider a mere splitting approach:
var idx = 2; // Might be user-defined
var subtext = "zero|one|two|three|four";
var result = subtext.Split('|').ElementAtOrDefault(idx);
Console.WriteLine(result);
// => two
A regex can be used if you have no access to code (if you use some tool that is powered with .NET regex):
^(?:[^|]*\|){2}([^|]*)
See the regex demo. It matches
^ - start of string
(?:[^|]*\|){2} - 2 (or adjust it as you need) or more sequences of:
[^|]* - zero or more chars other than |
\| - a | symbol
([^|]*) - Group 1 (access via .Groups[1]): zero or more chars other than |
C# code to test:
var pat = $#"^(?:[^|]*\|){{{idx}}}([^|]*)";
var m = Regex.Match(subtext, pat);
if (m.Success) {
Console.WriteLine(m.Groups[1].Value);
}
// => two
See the C# demo
If a tool does not let you access captured groups, turn the initial part into a non-consuming lookbehind pattern:
(?<=^(?:[^|]*\|){2})[^|]*
^^^^^^^^^^^^^^^^^^^^
See this regex demo. The (?<=...) positive lookbehind only checks for a pattern presence immediately to the left of the current location, and if the pattern is not matched, the match will fail.

Use this:
(?:.*?\|){n}(.[^|]*)
where n is the number of times you need to skip your special character. The first capturing group will contain the result.
Demo for n = 2

Use this regex and then select the n-th match (in this case 2) from the Matches collection:
string subtext = "zero|one|two|three|four";
Regex r = new Regex("(?<=\|)[^\|]*");
var m = r.Matches(subtext)[2];

REGEX help needed in c#

I am very new to reg-ex and i am not sure whats going on with this one.... however my friend gave me this to solve my issue BUT somehow it is not working....
string: department_name:womens AND item_type_keyword:base-layer-underwear
reg-ex: (department_name:([\\w-]+))?(item_type_keyword:([\\w-]+))?
desired output: array OR group
1st element should be: department_name:womens
2nd should be: womens
3rd: item_type_keyword:base-layer-underwear
4th: base-layer-underwear
strings can contain department_name OR item_type_keyword, BUT not mendatory, in any order
C# Code
Regex regex = new Regex(#"(department_name:([\w-]+))?(item_type_keyword:([\w-]+))?");
Match match = regex.Match(query);
if (match.Success)
if (!String.IsNullOrEmpty(match.Groups[4].ToString()))
d1.ItemType = match.Groups[4].ToString();
this C# code only returns string array with 3 element
1: department_name:womens
2: department_name:womens
3: womens
somehow it is duplicating 1st and 2nd element, i dont know why. BUT its not return the other elements that i expect..
can someone help me please...
when i am testing the regex online, it looks fine to me...
http://fiddle.re/crvw1
Thanks

You can use something like this to get the output you have in your question:
string txt = "department_name:womens AND item_type_keyword:base-layer-underwear";
var reg = new Regex(#"(?:department_name|item_type_keyword):([\w-]+)", RegexOptions.IgnoreCase);
var ms = reg.Matches(txt);
ArrayList results = new ArrayList();
foreach (Match match in ms)
{
results.Add(match.Groups[0].Value);
results.Add(match.Groups[1].Value);
}
// results is your final array containing all results
foreach (string elem in results)
{
Console.WriteLine(elem);
}
Prints:
department_name:womens
womens
item_type_keyword:base-layer-underwear
base-layer-underwear
match.Groups[0].Value gives the part that matched the pattern, while match.Groups[1].Value will give the part captured in the pattern.
In your first expression, you have 2 capture groups; hence why you have twice department_name:womens appearing.
Once you get the different elements, you should be able to put them in an array/list for further processing. (Added this part in edit)
The loop then allows you to iterate over each of the matches, which you cannot exactly do with if and .Match() (which is better suited for a single match, while here I'm enabling multiple matches so the order they are matched doesn't matter, or the number of matches).
ideone demo
(?:
department_name # Match department_name
| # Or
item_type_keyword # Match item_type_keyword
)
:
([\w-]+) # Capture \w and - characters

It's better to use the alternation (or logical OR) operator | because we don't know the order of the input string.
(department_name:([\w-]+))|(item_type_keyword:([\w-]+))
DEMO
String input = #"department_name:womens AND item_type_keyword:base-layer-underwear";
Regex rgx = new Regex(#"(?:(department_name:([\w-]+))|(item_type_keyword:([\w-]+)))");
foreach (Match m in rgx.Matches(input))
{
Console.WriteLine(m.Groups[1].Value);
Console.WriteLine(m.Groups[2].Value);
Console.WriteLine(m.Groups[3].Value);
Console.WriteLine(m.Groups[4].Value);
}
IDEONE

Another idea using a lookahead for capturing and getting all groups in one match:
^(?!$)(?=.*(department_name:([\w-]+))|)(?=.*(item_type_keyword:([\w-]+))|)
as a .NET String
"^(?!$)(?=.*(department_name:([\\w-]+))|)(?=.*(item_type_keyword:([\\w-]+))|)"
test at regexplanet (click on .NET); test at regex101.com
(add m multiline modifier if multiline input: "^(?m)...)

If you use any spliting with And Or , etc that you can use
(department_name:(.*?)) AND (item_type_keyword:(.*?)$)
•1: department_name:womens
•2: womens
•3: item_type_keyword:base-layer-underwear
•4: base-layer-underwear

(?=(department_name:\w+)).*?:([\w-]+)|(?=(item_type_keyword:.*)$).*?:([\w-]+)
Try this.This uses a lookahead to capture then backtrack and again capture.See demo.
http://regex101.com/r/lS5tT3/52

regex to strip number from var in string

I have a long string and I have a var inside it
var abc = '123456'
Now I wish to get the 123456 from it.
I have tried a regex but its not working properly
Regex regex = new Regex("(?<abc>+)=(?<var>+)");
Match m = regex.Match(body);
if (m.Success)
{
string key = m.Groups["var"].Value;
}
How can I get the number from the var abc?
Thanks for your help and time

var body = #" fsd fsda f var abc = '123456' fsda fasd f";
Regex regex = new Regex(#"var (?<name>\w*) = '(?<number>\d*)'");
Match m = regex.Match(body);
Console.WriteLine("name: " + m.Groups["name"]);
Console.WriteLine("number: " + m.Groups["number"]);
prints:
name: abc
number: 123456

Your regex is not correct:
(?<abc>+)=(?<var>+)
The + are quantifiers meaning that the previous characters are repeated at least once (and there are no characters since (?< ... > ... ) is named capture group and is not considered as a character per se.
You perhaps meant:
(?<abc>.+)=(?<var>.+)
And a better regex might be:
(?<abc>[^=]+)=\s*'(?<var>[^']+)'
[^=]+ will match any character except an equal sign.
\s* means any number of space characters (will also match tabs, newlines and form feeds though)
[^']+ will match any character except a single quote.
To specifically match the variable abc, you then put it like this:
(?<abc>abc)\s*=\s*'(?<var>[^']+)'
(I added some more allowances for spaces)

From the example you provided the number can be gotten such as
Console.WriteLine (
Regex.Match("var abc = '123456'", #"(?<var>\d+)").Groups["var"].Value); // 123456
\d+ means 1 or more numbers (digits).
But I surmise your data doesn't look like your example.

Try this:
var body = #"my word 1, my word 2, my word var abc = '123456' 3, my word x";
Regex regex = new Regex(#"(?<=var \w+ = ')\d+");
Match m = regex.Match(body);

Regular Expression Pattern C#

I have the following string that would require me to parse it via Regex in C#.
Format: rec_mnd.rate.current_rate.sum.QWD.RET : 214345
I would like to extract our the bold chars as group objects in a groupcollection.
QWD = 1 group
RET = 1 group
214345 = 1 group
what would the message pattern be like?

It would be something like this:
string s = "Format: rec_mnd.rate.current_rate.sum.QWD.RET : 214345";
Match m = Regex.Match(s, #"^Format: rec_mnd\.rate\.current_rate\.sum\.(.+?)\.(.+?) : (\d+)$");
if( m.Success )
{
Console.WriteLine(m.Groups[1].Value);
Console.WriteLine(m.Groups[2].Value);
Console.WriteLine(m.Groups[3].Value);
}
The question mark in the first two groups make that quantifier lazy: it will capture the least possible amount of characters. In other words, it captures until the first . it sees. Alternatively, you could use ([^.]+) in those groups, which explicitly captures everything except a period.
The last group explicitly only captures decimal digits. If your expression can have other values on the right side of the : you'd have to change that to .+ as well.

Please, make it a lot easier on yourself and label your groups to make it easier to understand what is going on in code.
RegEx myRegex = new Regex(#"rec_mnd\.rate\.current_rate\.sum\.(?<code>[A-Z]{3})\.(?<subCode>[A-Z]{3})\s*:\s*(?<number>\d+)");
var matches = myRegex.Matches(sourceString);
foreach(Match match in matches)
{
//do stuff
Console.WriteLine("Match");
Console.WriteLine("Code: " + match.Groups["code"].Value);
Console.WriteLine("SubCode: " + match.Groups["subCode"].Value);
Console.WriteLine("Number: " + match.Groups["number"].Value);
}

This should give you what you want regardless of what's between the .'s.
#"(?:.+\.){4}(.\w+)\.(\w+)\s?:\s?(\d+)"

C# regular expression match

18.jun. 7 noči od 515,00 EUR
here I would like to get 515,00 with a regular expression.
Regex regularExpr = new Regex(#rule.RegularExpression,
RegexOptions.Compiled | RegexOptions.Multiline |
RegexOptions.IgnoreCase | RegexOptions.Singleline |
RegexOptions.IgnorePatternWhitespace);
tagValue.Value = "18.jun. 7 noči od 515,00 EUR";
Match match = regularExpr.Match(tagValue.Value);
object value = match.Groups[2].Value;
regex is: \d+((.\d+)+(,\d+)?)?
but I always get an empty string (""). If I try this regex in Expresso I get an array of 3 values and the third is 515,00.
What is wrong with my C# code that I get an empty string?

Your regex matches the 18 (since the decimal parts are optional), and match.Groups[2] refers to the second capturing parenthesis (.\d+) which should correctly read (\.\d+) and hasn't participated in the match, therefore the empty string is returned.
You need to correct your regex and iterate over the results:
StringCollection resultList = new StringCollection();
Regex regexObj = new Regex(#"\d+(?:[.,]\d+)?");
Match matchResult = regexObj.Match(subjectString);
while (matchResult.Success) {
resultList.Add(matchResult.Value);
matchResult = matchResult.NextMatch();
}
resultList[2] will then contain your match.

Make sure you escaped everything properly when you created the regular expression.
Regex re = new Regex("\d+((.\d+)+(,\d+)?)?")
is very different from
Regex re = new Regex(#"\d+((.\d+)+(,\d+)?)?")
You probably want the second.

I suspect the result you're getting in Expresso is equivalent to this:
string s = "18.jun. 7 noči od 515,00 EUR";
Regex r = new Regex(#"\d+((.\d+)+(,\d+)?)?");
foreach (Match m in r.Matches(s))
{
Console.WriteLine(m.Value);
}
In other words, it's not the contents of the second capturing group you're seeing, it's the third match. This code shows it more clearly:
Console.WriteLine("{0,10} {1,10} {2,10} {3,10}",
#"Group 0", #"Group 1", #"Groups 2", #"Group 3");
Regex r = new Regex(#"\d+((.\d+)+(,\d+)?)?");
foreach (Match m in r.Matches(s))
{
Console.WriteLine("{0,10} {1,10} {2,10} {3,10}",
m.Groups[0].Value, m.Groups[1].Value, m.Groups[2].Value, m.Groups[3].Value);
}
output:
Group 0 Group 1 Group 2 Group 3
18
7
515,00 ,00 ,00
On to the regex itself. If you want to match only the price and not those other numbers, you need to be more specific. For example, if you know the ,00 part will always be present, you can use this regex:
#"(?n)\b\d+(\.\d+)*(,\d+)\b"
(?n) is the inline form of the ExplicitCapture option, which turns those two capturing groups into non-capturing groups. Of the RegexOptions you did specify, the only one that has any effect is Compiled, which speeds up matching of the regex slightly, at the expense of slowing down its construction and hogging memory. \b is a word boundary.
It looks like you're applying all those modifiers blindly to every regex when you construct them, which is not a good idea. If a particular regex needs a certain modifier, you should try to specify it in the regex itself with an inline modifier, like I did with (?n).