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Regex - Match multiple times in a string

I am trying to do a regex search on 'NNTSY` so that I can get two matches.
NNTS
NTSY
When I attempted to match using the pattern ?<NGrlyosylation>N[^P][ST][^P])", I am only getting one match, which is NNTS.
How can I use Regex to match NNTSY so that two matches can be found?
NOTE: Background info: Rosalind problem can be found here.
Here is my code.
input = "NNTSY";
Regex regex = new Regex("(?<NGrlyosylation>N[^P][ST][^P])", RegexOptions.Compiled | RegexOptions.IgnoreCase);
MatchCollection matches = regex.Matches(input);
foreach (Match match in matches)
{
// Need to add 1 to because match index is 0 based
const int offset = 1;
yield return match.Index + offset;
}

Finding overlapping matches is usually not allowed in most programming languages (except few).
So, I don't think there exists a pure regex way to solve this, but you can use Substring in C# with lookahead as
(?=N[^P][ST][^P]).
C# Code
string input = "NNTSY";
Regex regex = new Regex("(?=N[^P][ST][^P]).", RegexOptions.Compiled | RegexOptions.IgnoreCase);
Match match = regex.Match(input);
while (match.Success)
{
Console.WriteLine(input.Substring(match.Index, 4));
match = match.NextMatch();
}
Ideone Demo

Regex help for this expression with digits wanted

I am splitting given text wherever eachDELETEDDELETED occours, however some of my files contain text like:
each2,DELETED6,DELETED
eachDELETED2,DELETED
each5,DELETED15,DELETED
each5,DELETED5,DELETED2
I want to do a regex replace and turn these expressions into eachDELETEDDELETED.
I have tried using the follow code:
Regex ra = new Regex(#"eachDELETED\d, DELETED");
MatchCollection mcMatches = ra.Matches(extracted);
foreach (Match m in mcMatches)
{
if (m.Success)
{
// MessageBox.Show(m.Value.ToString());
richTextBox5.Text += "JJJJ------>" +m.Value + "\n";
}
}
But I'm not getting any matches.

The regex each\d*,*DELETED\d*,DELETED\d* matches all the sample data:
each2,DELETED6,DELETED
eachDELETED2,DELETED
each5,DELETED15,DELETED
each5,DELETED5,DELETED2
If the lack of the comma in the second line is a typo, use each\d*,DELETED\d*,DELETED\d*
Basically, \d matches a digit and * means zero or more times.

check pattern of HTTP GET using REGEXc#

I'm new to RegEx and having trouble getting pattern
have request with first line that look like
GET /someFolder/someSubfolder/someFile.fileExtenstion?param1=abc HTTP/1.1
I would like to check that the correct pattren exist
meaning first word GET later some valid URL than HTTP/verison
What I have till now is
string input = line;
Match match = Regex.Match(input, #"GET /([A-Za-z0-9-.+!*'();:#&=+$,/?%#[]])\ HTTP/1.1",
RegexOptions.IgnoreCase);
// check the Match instance.
if (match.Success)
{
string URL = match.Groups[1].Value;
}
But I get No match
What am I missing ?

You can simplify the regex a lot as
^GET.*HTTP\/1\.1$
^ anchors the regex at the start of the string.
.* matches anything
$ anchors the regex at end of string. Ensures that nothing followes the matched string
Regex Example

Old question but it deserve new answer for anyone looking for correctly matching HTTP Start Line and extract values from it.
The (.*) will not match white space, also escaping forward slash not necessary in C# and will lead to not match .
Here is sample code with named capturing group:
var httpRegex = new Regex(#"^(?<method>[a-zA-Z]+)\s(?<url>.+)\sHTTP/(?<major>\d)\.(?<minor>\d+)$");
var match = httpRegex.Match("GET http://www.google.com HTTP/1.1");
if (match.Success)
{
Console.WriteLine(
$"Method: {match.Groups["method"].Value}\r\n" +
$"Url: {match.Groups["url"].Value}\r\n" +
$"httpVersion: HTTP/{match.Groups["major"].Value}.{match.Groups["minor"].Value}"
);
}
Escaping forward slash required in languages like PHP and JavaScript, and here the same code for PHP with escaping https://regex101.com/r/2l7k83/1/

Regex to find special pattern

I have a string to parse. First I have to check if string contains special pattern:
I wanted to know if there is substrings which starts with "$(",
and end with ")",
and between those start and end special strings,there should not be
any white-empty space,
it should not include "$" character inside it.
I have a little regex for it in C#
string input = "$(abc)";
string pattern = #"\$\(([^$][^\s]*)\)";
Regex rgx = new Regex(pattern, RegexOptions.IgnoreCase);
MatchCollection matches = rgx.Matches(input);
foreach (var match in matches)
{
Console.WriteLine("value = " + match);
}
It works for many cases but failed at input= $(a$() , which inside the expression is empty. I wanted NOT to match when input is $().[ there is nothing between start and end identifiers].
What is wrong with my regex?

Note: [^$] matches a single character but not of $
Use the below regex if you want to match $()
\$\(([^\s$]*)\)
Use the below regex if you don't want to match $(),
\$\(([^\s$]+)\)
* repeats the preceding token zero or more times.
+ Repeats the preceding token one or more times.
Your regex \(([^$][^\s]*)\) is wrong. It won't allow $ as a first character inside () but it allows it as second or third ,, etc. See the demo here. You need to combine the negated classes in your regex inorder to match any character not of a space or $.

Your current regex does not match $() because the [^$] matches at least 1 character. The only way I can think of where you would have this match would be when you have an input containing more than one parens, like:
$()(something)
In those cases, you will also need to exclude at least the closing paren:
string pattern = #"\$\(([^$\s)]+)\)";
The above matches for example:
abc in $(abc) and
abc and def in $(def)$()$(abc)(something).

Simply replace the * with a + and merge the options.
string pattern = #"\$\(([^$\s]+)\)";
+ means 1 or more
* means 0 or more

Regex - Find from both sides only if it has spaces

I need some help on Regex. I need to find a word that is surrounded by whatever element, for example - *. But I need to match it only if it has spaces or nothing on the ether sides. For example if it is at start of the text I can't really have space there, same for end.
Here is what I came up to
string myString = "You will find *me*, and *me* also!";
string findString = #"(\*(.*?)\*)";
string foundText;
MatchCollection matchCollection = Regex.Matches(myString, findString);
foreach (Match match in matchCollection)
{
foundText = match.Value.Replace("*", "");
myString = myString.Replace(match.Value, "->" + foundText + "<-");
match.NextMatch();
}
Console.WriteLine(myString);
You will find ->me<-, and ->me<- also!
Works correct, the problem is when I add * in the middle of text, I don't want it to match then.
Example: You will find *m*e*, and *me* also!
Output: You will find ->m<-e->, and <-me* also!
How can I fix that?

Try the following pattern:
string findString = #"(?<=\s|^)\*(.*?)\*(?=\s|$)";
(?<=\s|^)X will match any X only if preceded by a space-char (\s), or the start-of-input, and
X(?=\s|$) matches any X if followed by a space-char (\s), or the end-of-input.
Note that it will not match *me* in foo *me*, bar since the second * has a , after it! If you want to match that too, you need to include the comma like this:
string findString = #"(?<=[\s,]|^)\*(.*?)\*(?=[\s,]|$)";
You'll need to expand the set [\s,] as you see fit, of course. You might want to add !, ? and . at the very least: [\s,!?.] (and no, . and ? do not need to be escaped inside a character-set!).
EDIT
A small demo:
string Txt = "foo *m*e*, bar";
string Pattern = #"(?<=[\s,]|^)\*(.*?)\*(?=[\s,]|$)";
Console.WriteLine(Regex.Replace(Txt, Pattern, ">$1<"));
which would print:
>m*e<

You can add "beginning of line or space" and "space or end of line" around your match:
(^|\s)\*(.*?)\*(\s|$)
You'll now need to refer to the middle capture group for the match string.