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Regular expression not working in dotnet C# but works in online editors [duplicate]

I want to get a Substring out of a String.
The Substring I want is a sequence of numerical characters.
Input
"abcdefKD-0815xyz42ghijk";
"dag4ah424KD-42ab333k";
"BeverlyHills90210KD-433Nokia3310";
Generally it could be any String, but they all have one thing in common:
There is a part that starts with KD-
and ends with a number
Everything after the number to be gone.
In the examples above this number would be 0815, 42, 433 respectively. But it could be any number
Right now I have a Substring that contains all numerical characters after KD- but I would like to have only the 0815ish part of the string.
What i have so far
String toMakeSub = "abcdef21KD-0815xyz429569468949489694694689ghijk";
toMakeSub = toMakeSub.Substring(toMakeSub.IndexOf("KD-") + "KD-".Length);
String result = Regex.Replace(toMakeSub, "[^0-9]", "");
The Result is 0815429569468949489694694689 but I want only the 0815 (it could be any length though so cutting after four digits is not possible).

Its as easy as the following pattern
(?<=KD-)\d+
The way to read this
(?<=subpattern) : Zero-width positive lookbehind assertion. Continues matching only if subpattern matches on the left.
\d : Matches any decimal digit.
+ : Matches previous element one or more times.
Example
var input = "abcdef21KD-0815xyz429569468949489694694689ghijk";
var regex = new Regex(#"(?<=KD-)\d+");
var match = regex.Match(input);
if (match.Success)
{
Console.WriteLine(match.Value);
}
input = "abcdef21KD-0815xyz429569468949489694694689ghijk, KD-234dsfsdfdsf";
// or to match multiple times
var matches = regex.Matches(input);
foreach (var matchValue in matches)
{
Console.WriteLine(matchValue);
}

Regular Expression for parsing ASCII data

Right now I have a couple separate regular expressions to filter data from a string but I'm curious if there's a way to do it all in one go.
Sample Data:
(DATA$0$34.0002,5.3114$34.0002,5.2925$34.0004,5.3214$34.0007,2.2527$34.0002,44.3604$34.0002,43.689$34.0004,38.3179$34.0007,8.1299)
Need to verify there's an open and close parentheses ( )
Need to verify there's a "DATA$0" after the open parenthesis
Need to split the results by $
Need to split that subset by comma
Need to capture only the last item of that subset (i.e. 5.3114, 5.2925, 5.3214, etc.)
My first check is on parenthesis using (([^)]+)) as my RegEx w/ RightToLeft & ExplicitCapture options (some lines can have multiple data sets).
Next I filter for the DATA$0 using (?:(DATA$0)
Finally I do my splits and take the last value in the array to get what I need but I'm trying to figure out if there's a better way.
string DataPattern = #"(?:\(DATA\$0)";
string ParenthesisPattern = #"\(([^)]+)\)";
RegexOptions options = RegexOptions.RightToLeft | RegexOptions.ExplicitCapture;
StreamReader sr = new StreamReader(FilePath);
while (!sr.EndOfStream)
{
string line = sr.ReadLine();
Console.WriteLine(line);
Match parentMatch = Regex.Match(line, ParenthesisPattern, options);
if (parentMatch.Success)
{
string value = parentMatch.Value;
Match dataMatch = Regex.Match(value, DataPattern);
if (dataMatch.Success)
{
string output = parentMatch.Value.Replace("(DATA$0", "").Replace(")", "");
string[] splitOutput = Regex.Split(output, #"\$");
foreach (string x in splitOutput)
{
if (!string.IsNullOrEmpty(x))
{
string[] splitDollar = Regex.Split(x, ",");
if (splitDollar.Length > 0)
Console.WriteLine("Value: " + splitDollar[splitDollar.Length - 1]);
}
}
}
else
Console.WriteLine("NO DATA");
}
else
Console.WriteLine("NO PARENTHESIS");
Console.ReadLine();
}
TIA

You can use
var results = Regex.Matches(text, #"(?<=\(DATA\$0[^()]*,)[^(),$]+(?=(?:\$[^()]*)?\))")
.Cast<Match>()
.Select(x => x.Value)
.ToList();
See the regex demo. Details:
(?<=\(DATA\$0[^()]*,) - a positive lookbehind that matches a location that is immediately preceded with (DATA$0, zero or more chars other than ( and ) (as many as possible) and a comma
[^(),$]+ - one or more chars other than (, ), $ and a comma
(?=(?:\$[^()]*)?\)) - the current location must be immediately followed with an optional occurrence of a $ char and then zero or more chars other than ( and ), and then a ) char.
An alternative:
var results = Regex.Matches(text, #"(?:\G(?!^)|\(DATA\$0)[^()]*?,([^(),$]+)(?=(?:\$[^()]*)?\))")
.Cast<Match>()
.Select(x => x.Groups[1].Value)
.ToList();
See the regex demo. Details:
(?:\G(?!^)|\(DATA\$0) - either the end of the previous successful match, or (DATA$0 string
[^()]*? - zero or more chars other than (, ), ,, as few as possible
, - a comma
([^(),$]+) - Group 1: one or more chars other than (, ), ,, $
(?=(?:\$[^()]*)?\)) - a positive lookahead matching the location that is immediately followed with an optional occurrence of a $ char followed with zero or more chars other than ( and ), and then a ) char.

Return a number from String after a specific word

I want to get a Substring out of a String.
The Substring I want is a sequence of numerical characters.
Input
"abcdefKD-0815xyz42ghijk";
"dag4ah424KD-42ab333k";
"BeverlyHills90210KD-433Nokia3310";
Generally it could be any String, but they all have one thing in common:
There is a part that starts with KD-
and ends with a number
Everything after the number to be gone.
In the examples above this number would be 0815, 42, 433 respectively. But it could be any number
Right now I have a Substring that contains all numerical characters after KD- but I would like to have only the 0815ish part of the string.
What i have so far
String toMakeSub = "abcdef21KD-0815xyz429569468949489694694689ghijk";
toMakeSub = toMakeSub.Substring(toMakeSub.IndexOf("KD-") + "KD-".Length);
String result = Regex.Replace(toMakeSub, "[^0-9]", "");
The Result is 0815429569468949489694694689 but I want only the 0815 (it could be any length though so cutting after four digits is not possible).

Its as easy as the following pattern
(?<=KD-)\d+
The way to read this
(?<=subpattern) : Zero-width positive lookbehind assertion. Continues matching only if subpattern matches on the left.
\d : Matches any decimal digit.
+ : Matches previous element one or more times.
Example
var input = "abcdef21KD-0815xyz429569468949489694694689ghijk";
var regex = new Regex(#"(?<=KD-)\d+");
var match = regex.Match(input);
if (match.Success)
{
Console.WriteLine(match.Value);
}
input = "abcdef21KD-0815xyz429569468949489694694689ghijk, KD-234dsfsdfdsf";
// or to match multiple times
var matches = regex.Matches(input);
foreach (var matchValue in matches)
{
Console.WriteLine(matchValue);
}

How to split string by another string

I have this string (it's from EDI data):
ISA*ESA?ISA*ESA?
The * indicates it could be any character and can be of any length.
? indicates any single character.
Only the ISA and ESA are guaranteed not to change.
I need this split into two strings which could look like this: "ISA~this is date~ESA|" and
"ISA~this is more data~ESA|"
How do I do this in c#?
I can't use string.split, because it doesn't really have a delimeter.

You can use Regex.Split for accomplishing this
string splitStr = "|", inputStr = "ISA~this is date~ESA|ISA~this is more data~ESA|";
var regex = new Regex($#"(?<=ESA){Regex.Escape(splitStr)}(?=ISA)", RegexOptions.Compiled);
var items = regex.Split(inputStr);
foreach (var item in items) {
Console.WriteLine(item);
}
Output:
ISA~this is date~ESA
ISA~this is more data~ESA|
Note that if your string between the ISA and ESA have the same pattern that we are looking for, then you will have to find some smart way around it.
To explain the Regex a bit:
(?<=ESA) Look-behind assertion. This portion is not captured but still matched
(?=ISA) Look-ahead assertion. This portion is not captured but still matched
Using these look-around assertions you can find the correct | character for splitting

Simply use the
int x = whateverString.indexOf("?ISA"); // replace ? with the actual character here
and then just use the substring from 0 to that indexOf, indexOf to length.
Edit:
If ? is not known,
can we just use the regex Pattern and Matcher.
Matcher matcher = Patter.compile("ISA.*ESA").match(whateverString);
if(matcher.find()) {
matcher.find();
int x = matcher.start();
}
Here x would give that start index of that match.
Edit: I mistakenly saw it as java one, for C#
string pattern = #"ISA.*ESA";
Regex myRegex = new Regex(pattern, RegexOptions.IgnoreCase);
Match m = myRegex.Match(whateverString); // m is the first match
while (m.Success)
{
Console.writeLine(m.value);
m = m.NextMatch(); // more matches
}

RegEx will probably be the best for this. See this link
Mask would be
ISA(?<data1>.*?)ESA.ISA(?<data2>.*?)ESA.
This will give you 2 groups with data you need
Match match = Regex.Match(input, #"ISA(?<data1>.*?)ESA.ISA(?<data2>.*?)ESA.",RegexOptions.IgnoreCase);
if (match.Success)
{
var data1 = match.Groups["data1"].Value;
var data2 = match.Groups["data2"].Value;
}
Use Regex.Matches If you need multiple matches found, and specify different RegexOptions if needed.

It's kinda hacky but you could do...
string x = "ISA*ESA?ISA*ESA?";
x = x.Replace("*","~"); // OR SOME OTHER DELIMITER
string[] y = x.Split('~');
Not perfect in all situations, but it could solve your problem simply.

You could split by "ISA" and "ESA" and then put the parts back together.
string input = "ISA~this is date~ESA|ISA~this is more data~ESA|";
string start = "ISA",
end = "ESA";
var splitedInput = input.Split(new[] { start, end }, StringSplitOptions.None);
var firstPart = $"{start}{splitedInput[1]}{end}{splitedInput[2]}";
var secondPart = $"{start}{splitedInput[3]}{end}{splitedInput[4]}";
firstPart = "ISA~this is date~ESA|"
secondPart = "ISA~this is more data~ESA|";

Use a Regex like ISA(.+?)ESA and select the first group
string input = "ISA~mycontent+ESA";
Match match = Regex.Match(input, #"ISA(.+?)ESA",RegexOptions.IgnoreCase);
if (match.Success)
{
string key = match.Groups[1].Value;
}

Instead of "splitting" by a string, I would instead describe your question as "grouping" by a string. This can easily be done using a regular expression:
Regular expression: ^(ISA.*?(?=ESA)ESA.)(ISA.*?(?=ESA)ESA.)$
Explanation:
^ - asserts position at start of the string
( - start capturing group
ISA - match string ISA exactly
.*?(?=ESA) - match any character 0 or more times, positive lookahead on the
string ESA (basically match any character until the string ESA is found)
ESA - match string ESA exactly
. - match any character
) - end capturing group
repeat one more time...
$ - asserts position at end of the string
Try it on Regex101
Example:
string input = "ISA~this is date~ESA|ISA~this is more data~ESA|";
Regex regex = new Regex(#"^(ISA.*?(?=ESA)ESA.)(ISA.*?(?=ESA)ESA.)$",
RegexOptions.Compiled);
Match match = regex.Match(input);
if (match.Success)
{
string firstValue = match.Groups[1].Value; // "ISA~this is date~ESA|"
string secondValue = match.Groups[2].Value; // "ISA~this is more data~ESA|"
}

There are two answers to the question "How to split a string by another string".
var matches = input.Split(new [] { "ISA" }, StringSplitOptions.RemoveEmptyEntries);
and
var matches = Regex.Split(input, "ISA").ToList();
However, the first removes empty entries, while the second does not.

Extract multiple values from a string

I need to extract values from a string.
string sTemplate = "Hi [FirstName], how are you and [FriendName]?"
Values I need returned:
FirstName
FriendName
Any ideas on how to do this?

You can use the following regex globally:
\[(.*?)\]
Explanation:
\[ : [ is a meta char and needs to be escaped if you want to match it literally.
(.*?) : match everything in a non-greedy way and capture it.
\] : ] is a meta char and needs to be escaped if you want to match it literally.
Example:
string input = "Hi [FirstName], how are you and [FriendName]?";
string pattern = #"\[(.*?)\]";
Regex rgx = new Regex(pattern, RegexOptions.IgnoreCase);
MatchCollection matches = rgx.Matches(input);
if (matches.Count > 0)
{
Console.WriteLine("{0} ({1} matches):", input, matches.Count);
foreach (Match match in matches)
Console.WriteLine(" " + match.Value);
}

If the format/structure of the text won't be changing at all, and assuming the square brackets were used as markers for the variable, you could try something like this:
string sTemplate = "Hi FirstName, how are you and FriendName?"
// Split the string into two parts. Before and after the comma.
string[] clauses = sTemplate.Split(',');
// Grab the last word in each part.
string[] names = new string[]
{
clauses[0].Split(' ').Last(), // Using LINQ for .Last()
clauses[1].Split(' ').Last().TrimEnd('?')
};
return names;

You will need to tokenize the text and then extract the terms.
string[] tokenizedTerms = new string[7];
char delimiter = ' ';
tokenizedTerms = sTemplate.Split(delimiter);
firstName = tokenizedTerms[1];
friendName = tokenizedTerms[6];
char[] firstNameChars = firstName.ToCharArray();
firstName = new String(firstNameChars, 0, firstNameChars.length - 1);
char[] friendNameChars = lastName.ToCharArray();
friendName = new String(friendNameChars, 0, friendNameChars.length - 1);
Explanation:
You tokenize the terms, which separates the string into a string array with each element being the char sequence between each delimiter, in this case between spaces which is the words. From this word array we know that we want the 3rd word (element) and the 7th word (element). However each of these terms have punctuation at the end. So we convert the strings to a char array then back to a string minus that last character, which is the punctuation.
Note:
This method assumes that since it is a first name, there will only be one string, as well with the friend name. By this I mean if the name is just Will, it will work. But if one of the names is Will Fisher (first and last name), then this will not work.