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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.

How to add data in array of strings in C#

I have a text box where I'm getting url, for ex:
http://www.amazon.com/black-series-650.
Now I would like to add /en black-series-650 an it looks like.My ouput should be like this.
http://www.amazon.com/en/black-series-650.

With this code you can apply for url like :
http://www.amazon.com/black-series-650/abc/ed/aaa
You can try this code :
var url = "http://www.amazon.com/black-series-650";
// var url = txt_OriginalUri.Text;
var tempUrl = url.Replace("http://", string.Empty);
var lastSlashIndex = tempUrl.IndexOf('/');
var resultUrl = "http://" + tempUrl.Insert(lastSlashIndex + 1, "en/");

var tmp = OriginalUri.Text;
var en = tmp.Replace("http://www.amazon.com", "http://www.amazon.com/en");
var lst = new List<string>();
lst.Add(OriginalUri.Text);
lst.Add(en);

Instead of dealing urls with Split function you should parse your url using System.Uri. Check the url segments and re-construct as per your need.

This should work for you:
string str = "http://www.amazon.com/black-series-650";
str = str.Insert(str.LastIndexOf("/"),"/en");

You could also try to find the last occurence by using string.LastIndexOf instead of splitting:
string url = txt_OriginalUri.Text;
int idx = url.LastIndexOf('/');
string newUrl = url.Insert(idx,"/en");

c# rewrite url parameter

I have a simple task without a simple solution.
I have a parameter in the browser that needs to be changed or rewritten
for instance www.contoso.com/countries.aspx?country=UK
all I need is to rewrite the parameter without checking the url so it might appear as:
www.contoso.com/countries.aspx?country=France
I have tried something like that but with no joy
string parameter2 = Request.QueryString["country"];
Context.RewritePath(parameter2.Replace("?country=", "France"));

You could do something like this:
var url = "www.contoso.com/countries.aspx?country={0}";
var country = "UK";
url = String.Format(url, country);
Alternatively you can do:
var url = Request.Url.AbsolutePath;
var country = Request.QueryString["country"];
url = url.Replace(country, "UK");
Then:
Response.Redirect(url);

Can you not read the whole URL into a string, split it on the '?' and then add your new bit to the first part of the string?
Something like this:
var url = Request.QueryString;
var newUrl = url.split('?');
url = newUrl[0] + "?country=France";
I dont know if that will work, its just a thought

If you want to replace the complete querystring, use
newVal = string.LastIndexOf("?");
and then
URL.Replace(oldVal, newVal);
OR if you have just one parameter in querystring and want to replace only value of it, use
newVal = string.LastIndexOf("=");
URL.Replace(oldVal, newVal);

Look at this detailed response for solution to your problem.

QueryString converted to URL-Encode using NameValueCollection

I am passing an encrypted URL string:
Default.aspx?S3tLlnIKKzE%3d
I want to pass that URL string back into the ASPX page in a variable.
protected string qs = string.Empty;
NameValueCollection qscollstring = HttpContext.Current.Request.QueryString;
qs = qscollstring[0];
Which return : S3tLlnIKKzE=
The value in qscollstring[0] is correct: S3tLlnIKKzE%3d
I understand the problem is URL-Encoding, but I cannot find a way to keep the string as is.
It seems that assigning the value from qscollstring[0] is: S3tLlnIKKzE%3d
to string changes the value : S3tLlnIKKzE=
I need to to stay: S3tLlnIKKzE%3d

Use HttpUtility.UrlEncode method to encode the string.
qs =HttpUtility.UrlEncode(qscollstring[0]);

You can also pull the value from the Uri of the current URL without having to Encode the value.
Sample:
Uri u = new Uri("http://localhost.com/default.aspx?S3tLlnIKKzE%3d");
string q = u.Query;
And part of your page:
string q = !String.IsNullOrEmpty(Request.Url.Query) && Request.Url.Query.Length > 1 ? Request.Url.Query.Substring(1) : Request.Url.Query;

Like me if you are searching for the reverse .. use
qs =HttpUtility.UrlDecode("S3tLlnIKKzE%3d");
to get back S3tLlnIKKzE=

Get url parts without host

I have a url like this :
http://www.somesite.com/mypage.aspx?myvalue1=hello&myvalue2=goodbye.
I want to get mypage.aspx?myvalue1=hello&myvalue2=goodbye from it . Can you tell me how can I get it ?

Like this:
new Uri(someString).PathAndQuery

var uri = new Uri("http://www.somesite.com/mypage.aspx?myvalue1=hello&myvalue2=goodbye");
string pathOnly = uri.LocalPath; // "/mypage.aspx"
string queryOnly = uri.Query; // "?myvalue1=hello&myvalue2=goodbye"
string pathAndQuery = uri.PathAndQuery; // "/mypage.aspx?myvalue1=hello&myvalue2=goodbye"

Place your string URL into a URI object and then use the AbsolutePath & Query properties to get the URL parts you need.
Or use the PathAndQuery property to get both, which is what you need.
More information can be found here:
http://msdn.microsoft.com/en-us/library/system.uri_members%28v=VS.71%29.aspx

new Uri(System.AppDomain.CurrentDomain.BaseDirectory).Segments