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How to use regex to extract a string with multiple curly braces?

I have this sample string
`{1:}{2:}{3:}{4:\r\n-}{5:}`
and I want to extract out only {4:\r\n-}
This is my code but it is not working.
var str = "{1:}{2:}{3:}{4:\r\n-}{5:}";
var regex = new Regex(#"{4:*.*-}");
var match = regex.Match(str);

You need to escape the special regex characters (in this case the opening and closing braces and the backslashes) in the search string. This would capture just that part:
var regex = new Regex("\{4:\\r\\n-\}");
... or if you wanted anything up to and including the slash before the closing brace (which is what it looks like you might be trying to do)...
var regex = new Regex("\{4:[^-]*-\}");

You just need to escape your \r and \n characters in your regular expression. You can use the Regex.Escape() method to escape characters in your regex string which returns a string of characters that are converted to their escaped form.
Working example: https://dotnetfiddle.net/6GLZrl
using System;
using System.Text.RegularExpressions;
public class Program
{
public static void Main()
{
string str = #"{1:}{2:}{3:}{4:\r\n-}{5:}";
string regex = #"{4:\r\n-}"; //Original regex
Match m = Regex.Match(str, Regex.Escape(regex));
if (m.Success)
{
Console.WriteLine("Found '{0}' at position {1}.", m.Value, m.Index);
}
else
{
Console.WriteLine("No match found");
}
}
}

Regex to parse URL from an excel formula

I have a formula in excel which upon reading from C# code looks like this
"=HYPERLINK(CONCATENATE(\"https://abc.efghi.rtyui.com/#/wqeqwq/\",#REF!,\"/asdasd\"), \"View asdas\")"
I want to use regex to fetch the URL from this string, i.e.
https://abc.efghi.rtyui.com/#/wqeqwq/#REF!/asdasd
The url can be different but the format of the formula will remain the same.
"=HYPERLINK(CONCATENATE(\"{SOME_STRING}\",#REF!,\"{SOME_STRING}\"), \"View asdas\")"

Try it like this:
(?<=HYPERLINK\(CONCATENATE\(")[^"]+
Demo
The positive lookbehind allows us to skip part in-front of the URL from the full match.
If you have an arbitrary number of whitespace in-between add some \s*, e.g. see this example that also shows the escaped = at the beginning of the string.
Sample Code:
using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = #"(?<=HYPERLINK\(CONCATENATE\("")[^""]+";
string input = #"=HYPERLINK(CONCATENATE(""https://abc.efghi.rtyui.com/#/wqeqwq/"",#REF!,""/asdasd""), ""View asdas"")";
RegexOptions options = RegexOptions.Multiline;
foreach (Match m in Regex.Matches(input, pattern, options))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
Addendum: Here is another technique that uses capturing groups and regex Replace to extract the resulting URL string (after CONCATENATE would have happened):
^\=HYPERLINK\(CONCATENATE\("([^"]+)",([^,]+),"([^"]+)".*$
Demo2
string pattern = #"^\=HYPERLINK\(CONCATENATE\(""([^""]+)"",([^,]+),""([^""]+)"".*$";
string substitution = #"$1$2$3";
string input = #"=HYPERLINK(CONCATENATE(""https://abc.efghi.rtyui.com/#/wqeqwq/"",#REF!,""/asdasd""), ""View asdas"")";
Regex regex = new Regex(pattern);
string result = regex.Replace(input, substitution, 1);

You can extract the URL from the formula using capturing groups in regular expression as given below:
string inputString = "=HYPERLINK(CONCATENATE(\"https://abc.efghi.rtyui.com/#/wqeqwq/\",#REF!,\"/asdasd\"), \"View asdas\")";
string regex = "CONCATENATE\\(\"([\\S]+)\",#REF!,\"([\\S]+)\"\\)";
Regex substringRegex = new Regex(regex, RegexOptions.IgnoreCase);
Match substringMatch = substringRegex.Match(inputString);
if (substringMatch.Success)
{
string url = substringMatch.Groups[1].Value + "#REF!" + substringMatch.Groups[2].Value;
}
I have defined two capturing groups in my regular expression. One for extracting part of the URL before #REF! and the other for extracting part of the URL after #REF!. Then I am concatenating all the extracted parts with #REF! to get the final URL.

Replace any string between quotes

Problem:
Cannot find a consistent way to replace a random string between quotes with a specific string I want. Any help would be greatly appreciated.
Example:
String str1 = "test=\"-1\"";
should become
String str2 = "test=\"31\"";
but also work for
String str3 = "test=\"foobar\"";
basically I want to turn this
String str4 = "test=\"antyhingCanGoHere\"";
into this
String str4 = "test=\"31\"";
Have tried:
Case insensitive Regex without using RegexOptions enumeration
How do you do case-insensitive string replacement using regular expressions?
Replace any character in between AnyText: and <usernameredacted#example.com> with an empty string using Regex?
Replace string in between occurrences
Replace a String between two Strings
Current code:
Regex RemoveName = new Regex("(?VARIABLE=\").*(?=\")", RegexOptions.IgnoreCase);
String convertSeccons = RemoveName.Replace(ruleFixed, "31");
Returns error:
System.ArgumentException was caught
Message=parsing "(?VARIABLE=").*(?=")" - Unrecognized grouping construct.
Source=System
StackTrace:
at System.Text.RegularExpressions.RegexParser.ScanGroupOpen()
at System.Text.RegularExpressions.RegexParser.ScanRegex()
at System.Text.RegularExpressions.RegexParser.Parse(String re, RegexOptions op)
at System.Text.RegularExpressions.Regex..ctor(String pattern, RegexOptions options, Boolean useCache)
at System.Text.RegularExpressions.Regex..ctor(String pattern, RegexOptions options)
at application.application.insertGroupID(String rule) in C:\Users\winserv8\Documents\Visual Studio 2010\Projects\application\application\MainFormLauncher.cs:line 298
at application.application.xmlqueryDB(String xmlSaveLocation, TextWriter tw, String ruleName) in C:\Users\winserv8\Documents\Visual Studio 2010\Projects\application\application\MainFormLauncher.cs:line 250
InnerException:
found answer
string s = Regex.Replace(ruleFixed, "VARIABLE=\"(.*)\"", "VARIABLE=\"31\"");
ruleFixed = s;
I found this code sample at Replace any character in between AnyText: and with an empty string using Regex? which is one of the links i previously posted and just had skipped over this syntax because i thought it wouldnt handle what i needed.

var str1 = "test=\"foobar\"";
var str2 = str1.Substring(0, str1.IndexOf("\"") + 1) + "31\"";
If needed add check for IndexOf != -1

I don't know if I understood you correct, but if you want to replace all chars inside string, why aren't you using simple regular expresission
String str = "test=\"-\"1\"";
Regex regExpr = new Regex("\".*\"", RegexOptions.IgnoreCase);
String result = regExpr.Replace(str , "\"31\"");
Console.WriteLine(result);
prints:
test="31"
Note: You can take advantage of plain old XAttribute
String ruleFixed = "test=\"-\"1\"";
var splited = ruleFixed.Split('=');
var attribute = new XAttribute(splited[0], splited[1]);
attribute.Value = "31";
Console.WriteLine(attribute);//prints test="31"

var parts = given.Split('=');
return string.Format("{0}=\"{1}\"", parts[0], replacement);

In the case that your string has other things in it besides just the key/value pair of key="value", then you need to make the value-match part not match quote marks, or it will match all the way from the first value to the last quote mark in the string.
If that is true, then try this:
Regex.Replace(ruleFixed, "(?<=VARIABLE\s*=\s*\")[^\"]*(?=\")", "31");
This uses negative look-behind to match the VARIABLE=" part (with optional white space around it so VARIABLE = " would work as well, and negative look-ahead to match the ending ", without including the look-ahead/behind in the final match, enabling you to just replace the value you want.
If not, then your solution will work, but is not optimal because you have to repeat the value and the quote marks in the replace text.

Assuming that the string within the quotes does not contain quotes itself, you can use this general pattern in order to find a position between a prefix and a suffix:
(?<=prefix)find(?=suffix)
In your case
(?<=\w+=").*?(?=")
Here we are using the prefix \w+=" where \w+ denotes word characters (the variable) and =" are the equal sign and the quote.
We want to find anything .*? until we encounter the next quote.
The suffix is simply the quote ".
string result = Regex.Replace(input, "(?<=\\w+=\").*?(?=\")", replacement);

Try this:
[^"\r\n]*(?:""[\r\n]*)*

var pattern = "\"(.*)?\"";
var regex = new Regex(pattern, RegexOptions.IgnoreCase);
var replacement = regex.Replace("test=\"hereissomething\"", "\"31\"");

string s = Regex.Replace(ruleFixed, "VARIABLE=\"(.*)\"", "VARIABLE=\"31\"");
ruleFixed = s;
I found this code sample at Replace any character in between AnyText: and <usernameredacted#example.com> with an empty string using Regex? which is one of the links i previously posted and just had skipped over this syntax because i thought it wouldnt handle what i needed.

String str1 = "test=\"-1\"";
string[] parts = str1.Split(new[] {'"'}, 3);
string str2 = parts.Length == 3 ? string.Join(#"\", parts.First(), "31", parts.Last()) : str1;

String str1 = "test=\"-1\"";
string res = Regex.Replace(str1, "(^+\").+(\"+)", "$1" + "31" + "$2");

Im pretty bad at RegEx but you could make a simple ExtensionMethod using string functions to do this.
public static class StringExtensions
{
public static string ReplaceBetweenQuotes(this string str, string replacement)
{
if (str.Count(c => c.Equals('"')) == 2)
{
int start = str.IndexOf('"') + 1;
str = str.Replace(str.Substring(start, str.LastIndexOf('"') - start), replacement);
}
return str;
}
}
Usage:
String str3 = "test=\"foobar\"";
str3 = str3.ReplaceBetweenQuotes("31");
returns: "test=\"31\""

Regex to match pattern in C#

I have a string in the following format
ABC=23:Qasd=56:Def=40.44
I would like to replace all the strings (ABC=, Qasd= and Def=) with empty string. The string after = can be anything. So my output string would be
23:56:40.44
It would be great if you can let me know the regex for that in C#

(^|:)[^=]*=
replaced with
$1
Matches the beginning of a string or a : and everything until and including =.
It is replaced with $1 to keep :.
C#
string strTargetString = #"ABC=23:Qasd=56:Def=40.44";
var myRegex = new Regex(#"(^|:)[^=]*=");
var result = myRegex.Replace(strTargetString, #"$1");
//result: 23:56:40.44
More examples:
ABC=hello:Qasd=56:Def=40.44 => hello:56:40.44

Match
^[^=]+=|(?<=:)[^=]+=
and replace with string.Empty
Regex.Replace("ABC=23:Qasd=56:Def=40.44", #"^[^=]+=|(?<=:)[^=]+=", string.Empty);

C# regular expression to find custom markers and take content

I have a string:
productDescription
In it are some custom tags such as:
[MM][/MM]
For example the string might read:
This product is [MM]1000[/MM] long
Using a regular expression how can I find those MM tags, take the content of them and replace everything with another string? So for example the output should be:
This product is 10 cm long

I think you'll need to pass a delegate to the regex for that.
Regex theRegex = new Regex(#"\[MM\](\d+)\[/MM\]");
text = theRegex.Replace(text, delegate(Match thisMatch)
{
int mmLength = Convert.ToInt32(thisMatch.Groups[1].Value);
int cmLength = mmLength / 10;
return cmLength.ToString() + "cm";
});

Using RegexDesigner.NET:
using System.Text.RegularExpressions;
// Regex Replace code for C#
void ReplaceRegex()
{
// Regex search and replace
RegexOptions options = RegexOptions.None;
Regex regex = new Regex(#"\[MM\](?<value>.*)\[\/MM\]", options);
string input = #"[MM]1000[/MM]";
string replacement = #"10 cm";
string result = regex.Replace(input, replacement);
// TODO: Do something with result
System.Windows.Forms.MessageBox.Show(result, "Replace");
}
Or if you want the orginal text back in the replacement:
Regex regex = new Regex(#"\[MM\](?<theText>.*)\[\/MM\]", options);
string replacement = #"${theText} cm";

A regex like this
\[(\w+)\](\d+)\[\/\w+\]
will find and collect the units (like MM) and the values (like 1000). That would at least allow you to use the pairs of parts intelligently to do the conversion. You could then put the replacement string together, and do a straightforward string replacement, because you know the exact string you're replacing.
I don't think you can do a simple RegEx.Replace, because you don't know the replacement string at the point you do the search.

Regex rex = new Regex(#"\[MM\]([0-9]+)\[\/MM\]");
string s = "This product is [MM]1000[/MM] long";
MatchCollection mc = rex.Matches(s);
Will match only integers.
mc[n].Groups[1].Value;
will then give the numeric part of nth match.