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Cannot Convert from Http.QueryString to System.collections.IEqualityComparer [duplicate]

I am given an absolute URI that contains a query string. I'm looking to safely append a value to the query string, and change an existing parameter.
I would prefer not to tack on &foo=bar, or use regular expressions, URI escaping is tricky. Rather I want to use a built-in mechanism that I know will do this correctly and handle the escaping.
I've found a ton of answers that all use HttpUtility. However this being ASP.NET Core, there is no more System.Web assembly anymore, thus no more HttpUtility.
What is the appropriate way to do this in ASP.NET Core while targeting the core runtime?

If you are using ASP.NET Core 1 or 2, you can do this with Microsoft.AspNetCore.WebUtilities.QueryHelpers in the Microsoft.AspNetCore.WebUtilities package.
If you are using ASP.NET Core 3.0 or greater, WebUtilities is now part of the ASP.NET SDK and does not require a separate nuget package reference.
To parse it into a dictionary:
var uri = new Uri(context.RedirectUri);
var queryDictionary = Microsoft.AspNetCore.WebUtilities.QueryHelpers.ParseQuery(uri.Query);
Note that unlike ParseQueryString in System.Web, this returns a dictionary of type IDictionary<string, string[]> in ASP.NET Core 1.x, or IDictionary<string, StringValues> in ASP.NET Core 2.x or greater, so the value is a collection of strings. This is how the dictionary handles multiple query string parameters with the same name.
If you want to add a parameter on to the query string, you can use another method on QueryHelpers:
var parametersToAdd = new System.Collections.Generic.Dictionary<string, string> { { "resource", "foo" } };
var someUrl = "http://www.google.com";
var newUri = Microsoft.AspNetCore.WebUtilities.QueryHelpers.AddQueryString(someUrl, parametersToAdd);
Using .net core 2.2 you can get the query string using
var request = HttpContext.Request;
var query = request.Query;
foreach (var item in query){
Debug.WriteLine(item)
}
You will get a collection of key:value pairs - like this
[0] {[companyName, ]}
[1] {[shop, ]}
[2] {[breath, ]}
[3] {[hand, ]}
[4] {[eye, ]}
[5] {[firstAid, ]}
[6] {[eyeCleaner, ]}

The easiest and most intuitive way to take an absolute URI and manipulate it's query string using ASP.NET Core packages only, can be done in a few easy steps:
Install Packages
PM> Install-Package Microsoft.AspNetCore.WebUtilities
PM> Install-Package Microsoft.AspNetCore.Http.Extensions
Important Classes
Just to point them out, here are the two important classes we'll be using: QueryHelpers, StringValues, QueryBuilder.
The Code
// Raw URI including query string with multiple parameters
var rawurl = "https://bencull.com/some/path?key1=val1&key2=val2&key2=valdouble&key3=";
// Parse URI, and grab everything except the query string.
var uri = new Uri(rawurl);
var baseUri = uri.GetComponents(UriComponents.Scheme | UriComponents.Host | UriComponents.Port | UriComponents.Path, UriFormat.UriEscaped);
// Grab just the query string part
var query = QueryHelpers.ParseQuery(uri.Query);
// Convert the StringValues into a list of KeyValue Pairs to make it easier to manipulate
var items = query.SelectMany(x => x.Value, (col, value) => new KeyValuePair<string, string>(col.Key, value)).ToList();
// At this point you can remove items if you want
items.RemoveAll(x => x.Key == "key3"); // Remove all values for key
items.RemoveAll(x => x.Key == "key2" && x.Value == "val2"); // Remove specific value for key
// Use the QueryBuilder to add in new items in a safe way (handles multiples and empty values)
var qb = new QueryBuilder(items);
qb.Add("nonce", "testingnonce");
qb.Add("payerId", "pyr_");
// Reconstruct the original URL with new query string
var fullUri = baseUri + qb.ToQueryString();
To keep up to date with any changes, you can check out my blog post about this here: http://benjii.me/2017/04/parse-modify-query-strings-asp-net-core/

HttpRequest has a Query property which exposes the parsed query string via the IReadableStringCollection interface:
/// <summary>
/// Gets the query value collection parsed from owin.RequestQueryString.
/// </summary>
/// <returns>The query value collection parsed from owin.RequestQueryString.</returns>
public abstract IReadableStringCollection Query { get; }
This discussion on GitHub points to it as well.

This function return Dictionary<string, string> and does not use Microsoft.xxx for compatibility
Accepts parameter encoding in both sides
Accepts duplicate keys (return last value)
var rawurl = "https://emp.com/some/path?key1.name=a%20line%20with%3D&key2=val2&key2=valdouble&key3=&key%204=44#book1";
var uri = new Uri(rawurl);
Dictionary<string, string> queryString = ParseQueryString(uri.Query);
// queryString return:
// key1.name, a line with=
// key2, valdouble
// key3,
// key 4, 44
public Dictionary<string, string> ParseQueryString(string requestQueryString)
{
Dictionary<string, string> rc = new Dictionary<string, string>();
string[] ar1 = requestQueryString.Split(new char[] { '&', '?' });
foreach (string row in ar1)
{
if (string.IsNullOrEmpty(row)) continue;
int index = row.IndexOf('=');
if (index < 0) continue;
rc[Uri.UnescapeDataString(row.Substring(0, index))] = Uri.UnescapeDataString(row.Substring(index + 1)); // use Unescape only parts
}
return rc;
}

It's important to note that in the time since the top answer has been flagged as correct that Microsoft.AspNetCore.WebUtilities has had a major version update (from 1.x.x to 2.x.x).
That said, if you're building against netcoreapp1.1 you will need to run the following, which installs the latest supported version 1.1.2:
Install-Package Microsoft.AspNetCore.WebUtilities -Version 1.1.2

I use this as extention method, works with any number of params:
public static string AddOrReplaceQueryParameter(this HttpContext c, params string[] nameValues)
{
if (nameValues.Length%2!=0)
{
throw new Exception("nameValues: has more parameters then values or more values then parameters");
}
var qps = new Dictionary<string, StringValues>();
for (int i = 0; i < nameValues.Length; i+=2)
{
qps.Add(nameValues[i], nameValues[i + 1]);
}
return c.AddOrReplaceQueryParameters(qps);
}
public static string AddOrReplaceQueryParameters(this HttpContext c, Dictionary<string,StringValues> pvs)
{
var request = c.Request;
UriBuilder uriBuilder = new UriBuilder
{
Scheme = request.Scheme,
Host = request.Host.Host,
Port = request.Host.Port ?? 0,
Path = request.Path.ToString(),
Query = request.QueryString.ToString()
};
var queryParams = QueryHelpers.ParseQuery(uriBuilder.Query);
foreach (var (p,v) in pvs)
{
queryParams.Remove(p);
queryParams.Add(p, v);
}
uriBuilder.Query = "";
var allQPs = queryParams.ToDictionary(k => k.Key, k => k.Value.ToString());
var url = QueryHelpers.AddQueryString(uriBuilder.ToString(),allQPs);
return url;
}
Next and prev links for example in a view:
var next = Context.Request.HttpContext.AddOrReplaceQueryParameter("page",Model.PageIndex+1+"");
var prev = Context.Request.HttpContext.AddOrReplaceQueryParameter("page",Model.PageIndex-1+"");

I'm not sure at what point it was added but as early as .NET Core 3.1 HttpUtility.ParseQueryString is available and built into the standard .NET Microsoft.NETCore.App framework. I was able to access it from a class library with no additional NuGet packages or special dll references required.
I've tested it with .NET Core 3.1, .NET 6, and .NET 7.
The benefit of this approach is that you do not have to reference any web libraries which will add bloat to your project if you are building a library that may be used outside of the context of ASP.NET.
... of course, if you are needing this within an ASP.NET Core app, the Microsoft.AspNetCore.WebUtilities class suggested by others is perfectly valid.
EDIT: #KTCO pointed out in his comment on the OP back in 2017 that this class was available in .NET Core 2.0 as well.

Easier way to extract ID from a string? [duplicate]

I would like to parse a string such as p1=6&p2=7&p3=8 into a NameValueCollection.
What is the most elegant way of doing this when you don't have access to the Page.Request object?

There's a built-in .NET utility for this: HttpUtility.ParseQueryString
// C#
NameValueCollection qscoll = HttpUtility.ParseQueryString(querystring);
' VB.NET
Dim qscoll As NameValueCollection = HttpUtility.ParseQueryString(querystring)
You may need to replace querystring with new Uri(fullUrl).Query.

HttpUtility.ParseQueryString will work as long as you are in a web app or don't mind including a dependency on System.Web. Another way to do this is:
NameValueCollection queryParameters = new NameValueCollection();
string[] querySegments = queryString.Split('&');
foreach(string segment in querySegments)
{
string[] parts = segment.Split('=');
if (parts.Length > 0)
{
string key = parts[0].Trim(new char[] { '?', ' ' });
string val = parts[1].Trim();
queryParameters.Add(key, val);
}
}

A lot of the answers are providing custom examples because of the accepted answer's dependency on System.Web. From the Microsoft.AspNet.WebApi.Client NuGet package there is a UriExtensions.ParseQueryString, method that can also be used:
var uri = new Uri("https://stackoverflow.com/a/22167748?p1=6&p2=7&p3=8");
NameValueCollection query = uri.ParseQueryString();
So if you want to avoid the System.Web dependency and don't want to roll your own, this is a good option.

I wanted to remove the dependency on System.Web so that I could parse the query string of a ClickOnce deployment, while having the prerequisites limited to the "Client-only Framework Subset".
I liked rp's answer. I added some additional logic.
public static NameValueCollection ParseQueryString(string s)
{
NameValueCollection nvc = new NameValueCollection();
// remove anything other than query string from url
if(s.Contains("?"))
{
s = s.Substring(s.IndexOf('?') + 1);
}
foreach (string vp in Regex.Split(s, "&"))
{
string[] singlePair = Regex.Split(vp, "=");
if (singlePair.Length == 2)
{
nvc.Add(singlePair[0], singlePair[1]);
}
else
{
// only one key with no value specified in query string
nvc.Add(singlePair[0], string.Empty);
}
}
return nvc;
}

To do this without System.Web, without writing it yourself, and without additional NuGet packages:
Add a reference to System.Net.Http.Formatting
Add using System.Net.Http;
Use this code:
new Uri(uri).ParseQueryString()
https://msdn.microsoft.com/en-us/library/system.net.http.uriextensions(v=vs.118).aspx

I needed a function that is a little more versatile than what was provided already when working with OLSC queries.
Values may contain multiple equal signs
Decode encoded characters in both name and value
Capable of running on Client Framework
Capable of running on Mobile Framework.
Here is my solution:
Public Shared Function ParseQueryString(ByVal uri As Uri) As System.Collections.Specialized.NameValueCollection
Dim result = New System.Collections.Specialized.NameValueCollection(4)
Dim query = uri.Query
If Not String.IsNullOrEmpty(query) Then
Dim pairs = query.Substring(1).Split("&"c)
For Each pair In pairs
Dim parts = pair.Split({"="c}, 2)
Dim name = System.Uri.UnescapeDataString(parts(0))
Dim value = If(parts.Length = 1, String.Empty,
System.Uri.UnescapeDataString(parts(1)))
result.Add(name, value)
Next
End If
Return result
End Function
It may not be a bad idea to tack <Extension()> on that too to add the capability to Uri itself.

If you don't want the System.Web dependency, just paste this source code from HttpUtility class.
I just whipped this together from the source code of Mono. It contains the HttpUtility and all it's dependencies (like IHtmlString, Helpers, HttpEncoder, HttpQSCollection).
Then use HttpUtility.ParseQueryString.
https://gist.github.com/bjorn-ali-goransson/b04a7c44808bb2de8cca3fc9a3762f9c

If you want to avoid the dependency on System.Web that is required to use HttpUtility.ParseQueryString, you could use the Uri extension method ParseQueryString found in System.Net.Http.
Make sure to add a reference (if you haven't already) to System.Net.Http in your project.
Note that you have to convert the response body to a valid Uri so that ParseQueryString (in System.Net.Http)works.
string body = "value1=randomvalue1&value2=randomValue2";
// "http://localhost/query?" is added to the string "body" in order to create a valid Uri.
string urlBody = "http://localhost/query?" + body;
NameValueCollection coll = new Uri(urlBody).ParseQueryString();

I just realized that Web API Client has a ParseQueryString extension method that works on a Uri and returns a HttpValueCollection:
var parameters = uri.ParseQueryString();
string foo = parameters["foo"];

private void button1_Click( object sender, EventArgs e )
{
string s = #"p1=6&p2=7&p3=8";
NameValueCollection nvc = new NameValueCollection();
foreach ( string vp in Regex.Split( s, "&" ) )
{
string[] singlePair = Regex.Split( vp, "=" );
if ( singlePair.Length == 2 )
{
nvc.Add( singlePair[ 0 ], singlePair[ 1 ] );
}
}
}

Just access Request.QueryString. AllKeys mentioned as another answer just gets you an array of keys.

HttpUtility.ParseQueryString(Request.Url.Query) return is HttpValueCollection (internal class). It inherits from NameValueCollection.
var qs = HttpUtility.ParseQueryString(Request.Url.Query);
qs.Remove("foo");
string url = "~/Default.aspx";
if (qs.Count > 0)
url = url + "?" + qs.ToString();
Response.Redirect(url);

Since everyone seems to be pasting his solution.. here's mine :-)
I needed this from within a class library without System.Web to fetch id parameters from stored hyperlinks.
Thought I'd share because I find this solution faster and better looking.
public static class Statics
public static Dictionary<string, string> QueryParse(string url)
{
Dictionary<string, string> qDict = new Dictionary<string, string>();
foreach (string qPair in url.Substring(url.IndexOf('?') + 1).Split('&'))
{
string[] qVal = qPair.Split('=');
qDict.Add(qVal[0], Uri.UnescapeDataString(qVal[1]));
}
return qDict;
}
public static string QueryGet(string url, string param)
{
var qDict = QueryParse(url);
return qDict[param];
}
}
Usage:
Statics.QueryGet(url, "id")

Hit up Request.QueryString.Keys for a NameValueCollection of all query string parameters.

To get all Querystring values try this:
Dim qscoll As NameValueCollection = HttpUtility.ParseQueryString(querystring)
Dim sb As New StringBuilder("<br />")
For Each s As String In qscoll.AllKeys
Response.Write(s & " - " & qscoll(s) & "<br />")
Next s

var q = Request.QueryString;
NameValueCollection qscoll = HttpUtility.ParseQueryString(q.ToString());

I translate to C# version of josh-brown in VB
private System.Collections.Specialized.NameValueCollection ParseQueryString(Uri uri)
{
var result = new System.Collections.Specialized.NameValueCollection(4);
var query = uri.Query;
if (!String.IsNullOrEmpty(query))
{
var pairs = query.Substring(1).Split("&".ToCharArray());
foreach (var pair in pairs)
{
var parts = pair.Split("=".ToCharArray(), 2);
var name = System.Uri.UnescapeDataString(parts[0]);
var value = (parts.Length == 1) ? String.Empty : System.Uri.UnescapeDataString(parts[1]);
result.Add(name, value);
}
}
return result;
}

let search = window.location.search;
console.log(search);
let qString = search.substring(1);
while(qString.indexOf("+") !== -1)
qString = qString.replace("+", "");
let qArray = qString.split("&");
let values = [];
for(let i = 0; i < qArray.length; i++){
let pos = qArray[i].search("=");
let keyVal = qArray[i].substring(0, pos);
let dataVal = qArray[i].substring(pos + 1);
dataVal = decodeURIComponent(dataVal);
values[keyVal] = dataVal;
}

This is my code, I think it's very useful:
public String GetQueryString(string ItemToRemoveOrInsert = null, string InsertValue = null )
{
System.Collections.Specialized.NameValueCollection filtered = new System.Collections.Specialized.NameValueCollection(Request.QueryString);
if (ItemToRemoveOrInsert != null)
{
filtered.Remove(ItemToRemoveOrInsert);
if (!string.IsNullOrWhiteSpace(InsertValue))
{
filtered.Add(ItemToRemoveOrInsert, InsertValue);
}
}
string StrQr = string.Join("&", filtered.AllKeys.Select(key => key + "=" + filtered[key]).ToArray());
if (!string.IsNullOrWhiteSpace(StrQr)){
StrQr="?" + StrQr;
}
return StrQr;
}

How to get a parameter from a URL encoded?

I have the following code to get parameters and their key from a URL:
string queryString = new Uri(URL).Query;
var queryDictionary = System.Web.HttpUtility.ParseQueryString(queryString);
var paramsList = new Dictionary<string, string>();
foreach (var parameter in queryDictionary)
{
var key = (string)parameter;
var value = System.Web.HttpUtility.ParseQueryString(queryString).Get(key);
}
It works perfect. Exception, in value, I have the decoded value. I would need to have it as it was in the address, before it was decoded. How can I do it? Note that to encoded it after gives different value in some cases.

The encoding is happening in your first line already:
string queryString = new Uri(URL).Query;
Presumably you want to avoid writing your own code to extract the Query part from a URL. Which is sensible. You can still rely on the Uri class to do the parsing for you:
var uri=new Uri(URL);
var queryString= URL.Replace(uri.GetLeftPart(UriPartial.Path), "").TrimStart('?');
———————————————————————————————————
(
var URL="http://a/b/?d= #£$%% sdf we 456 7 5?367";
var uri=new Uri(URL);
Console.WriteLine(uri.Query); // Already url-encoded by the Uri constructor
var queryString = URL.Replace(uri.GetLeftPart(UriPartial.Path), "").TrimStart('?');
Console.WriteLine(System.Web.HttpUtility.ParseQueryString(queryString)); //Not encoded!
)
(As an aside, LinqPad helps)

A possible way of doing this is to encode it back:
var encodedValue = HttpUtility.UrlEncode(value);
ASP.NET automatically calls HttpUtility.UrlDecode when you access the query string.
This is a bit dirty, but should work fine.

Replace {x} tokens in strings

We have a template URL like:
http://api.example.com/sale?auth_user=xxxxx&auth_pass=xxxxx&networkid={networkid}&category=b2c&country=IT&pageid={pageid}&programid=133&saleid=1&m={master}&optinfo={optinfo}&publisher={publisher}&msisdn={userId}
and I have values for these constant tokens. How can replace all these tokens in C#?

A simple approach is to use a foreach and a Dictionary with a String.Replace:
var values = new Dictionary<string, string> {
{ "{networkid}", "WHEEE!!" }
// etc.
};
var url = "http://api.example.com/sale?auth_user=xxxxx&auth_pass=xxxxx&networkid={networkid}&category=b2c&country=IT&pageid={pageid}&programid=133&saleid=1&m={master}&optinfo={optinfo}&publisher={publisher}&msisdn={userId}";
foreach(var key in values.Keys){
url = url.Replace(key,values[key]);
}

There is no standard way to "replace with dictionary values" in .NET. While there are a number of template engines, it's not very hard to write a small solution for such an operation. Here is an example which runs in LINQPad and utilizes a Regular Expression with a Match Evaluator.
As the result is a URL,
it is the callers responsibility to make sure all the supplied values are correctly encoded. I recommend using Uri.EscapeDataString as appropriate .. but make sure to not double-encode, if it is processed elsewhere.
Additionally, the rules of what to do when no replacement is found should be tailored to need. If not-found replacements should be eliminated entirely along with the query string key, the following can expand the regular expression to #"\w+=({\w+})" to also capture the parameter key in this specific template situation.
string ReplaceUsingDictionary (string src, IDictionary<string, object> replacements) {
return Regex.Replace(src, #"{(\w+)}", (m) => {
object replacement;
var key = m.Groups[1].Value;
if (replacements.TryGetValue(key, out replacement)) {
return Convert.ToString(replacement);
} else {
return m.Groups[0].Value;
}
});
}
void Main()
{
var replacements = new Dictionary<string, object> {
{ "networkid", "WHEEE!!" }
// etc.
};
var src = "http://api.example.com/sale?auth_user=xxxxx&auth_pass=xxxxx&networkid={networkid}&category=b2c&country=IT&pageid={pageid}&programid=133&saleid=1&m={master}&optinfo={optinfo}&publisher={publisher}&msisdn={userId}";
var res = ReplaceUsingDictionary(src, replacements);
// -> "http://api.example.com/sale?..&networkid=WHEEE!!&..&pageid={pageid}&..
res.Dump();
}
More advanced techniques, like reflection and transforms, are possible - but those should be left for the real template engines.

I am guessing you are trying to replace parameters in url with your values. This can be done using C# HttpUtility.ParseQueryString
Get the CurrentURL from
var _myUrl = System.Web.HttpUtility.ParseQueryString(Request.RawUrl);
Read Parameter from your Query string
string value1 = _myUrl ["networkid"];
Write a value into the QueryString object.
_myUrl ["networkid"] = "Your Value";
and then finally turn it back into URL
var _yourURIBuilder= new UriBuilder(_myUrl );
_myUrl = _yourURIBuilder.ToString();

You can use this alos using LinQ
Dictionary<string, string> myVal = new Dictionary<string, string>();
myVal.Add("networkid", "1");
myVal.Add("pageid", "2");
myVal.Add("master", "3");
myVal.Add("optinfo", "4");
myVal.Add("publisher", "5");
myVal.Add("userId", "6");
string url = #"http://api.example.com/sale?auth_user=xxxxx&auth_pass=xxxxx&networkid={networkid}&category=b2c&country=IT&pageid={pageid}&programid=133&saleid=1&m={master}&optinfo={optinfo}&publisher={publisher}&msisdn={userId}";
myVal.Select(a => url = url.Replace(string.Concat("{", a.Key, "}"), a.Value)).ToList();
this line can do your required functionlity
myVal.Select(a => url = url.Replace(string.Concat("{", a.Key, "}"), a.Value)).ToList();

There is a Nuget called StringTokenFormatter that does this well
https://www.nuget.org/packages/StringTokenFormatter/

Regex.Replace makes a single pass over a template string, offering you an opportunity to replace matched expressions. Use it by creating an regular expression that matches any token. Then look up replacement values for the tokens in a dictionary.
static string ReplaceTokens(string template, Dictionary<string, string> replacements) =>
Regex.Replace(template, #"{(\w+)}",
match => replacements.TryGetValue(match.Groups[1].Value, out string replacement) ? replacement : match.Value);
The algorithm completes in time linear with the size of the template string and the replacement strings, so O(t + r). Beware of algorithms that make multiple passes. They run slowly in time O(t * r) and will give incorrect results if one of the replacement values contains a token for later replacement. This unit test shows the pitfall:
public void TestReplaceTokens() {
var replacements = new Dictionary<string, string> {
["Movement"] = "drive {DontReplace}",
["DontReplace"] = "Should not appear"
};
string withReplacements = ReplaceTokens("I always {Movement} in {Direction}.", replacements);
Assert.AreEqual("I always drive {DontReplace} in {Direction}.", withReplacements);
}

c# - regex to find a string that comes after = [duplicate]

This question already has answers here:
regex to find a string that comes after =
(6 answers)
Closed 9 years ago.
So I asked this question before and said I wanted it in javascript but realized later on that it's unecessary data being sent. So it would be great if anybody could help me solve the same thing in C#
What I need is to get several properties out of a string.
The string will look something like:
str = "car[brand=saab][wheels=4]";
There can be more or fewer properties.
I need everything before the first [] in 1 variable.
Then I need each property and its value in a variable.
Easiest way to understand what I want is probably to check my previous question and the answer that solved it :)

I used the regex(slightly different) in your previous question.
string input = "car[brand=saab][wheels=4]";
string product = "";
Dictionary<string, string> props = new Dictionary<string, string>();
foreach (Match m in Regex.Matches(input, #"^(\w+)|\[(\w+)=(.+?)\]"))
{
if (String.IsNullOrEmpty(product))
product = m.Groups[1].Value;
else
props.Add(m.Groups[2].Value, m.Groups[3].Value);
}

try this regex:
(.+?)(\[.+?\])+
and a sample code:
var inputString = "car[brand=saab][wheels=4]";
var pattern = #"(?<v1>.+?)(?<v2>\[.+?\])+";
var v1 = Regex.Match(inputString, pattern).Groups["v1"].Value;
Dictionary<String, String> list = new Dictionary<String, String>();
foreach (Capture capture in Regex.Match(inputString, pattern).Groups["v2"].Captures)
{
var sp = capture.Value.Split('=');
list.Add(sp[0], sp[1]);
}
explain:
(?<name>subexpression)
Captures the matched subexpression into a named group.

You can do this
var lst=Regex.Matches(input,#"(\w+)((?:\[.*?\])+)")
.Cast<Match>()
.Select(x=>new
{
name=x.Groups[1].Value,
value=Regex.Matches(x.Groups[2].Value,#"(?<=\[).*?(?=\])")
.Cast<Match>()
.Select(x=>new
{
name=x.Groups[0].Value.Split('=')[0],
value=x.Groups[0].Value.Split('=')[1]
})
});
Now you can iterate over lst like this
foreach(var parent in lst)
{
parent.name;//car
foreach(var pairs in parent.value)
{
pairs.name;//brand,wheels
pairs.value;//ferrari,4
}
}
So,for input car[brand=a][wheels=4]cycle[brand=b][wheels=2]
Output would be like
car
brand,a
wheels,4
cycle
brand,b
wheels,2

Without regex:
string input = "car[brand=saab][wheels=4]";
var query = from s in input.Replace("]", "").Split('[')
let vars = s.Split('=')
let name = vars[0]
let value = vars.Length > 1 ? vars[1] : ""
select new {Name = name, Value = value};
string firstVar = query.First().Name;
Dictionary<string, string> otherVars = query
.Skip(1)
.ToDictionary(v => v.Name, v => v.Value);
You can access your variables in the dictionary like this string brand = otherVars["brand"]

Since you already have an answer using regex and your comments state it doesn't have to be with a regex, I'll offer an alternative:
The code is
string str = ("car[brand=saab][wheels=4]");
int i = str.IndexOf("[");
string[] details =str.Substring(i).Replace("]","").Split('[');
string name = str.Substring(0, i);
string brand = details[1].Split('=')[1];
string wheels = details[2].Split('=')[1];
This approach assumes the data is always going to be in the same format though; you may need some validation in there depending on your needs...