How to URL encode strings in C#

Question

How can we encode a string using the URL (RFC 1738) standard in C#?

The following online tool is converting the strings using this standard http://www.freeformatter.com/url-encoder.html

An example of the string I want to convert is test(brackets) and the encoded string should look like:

test%28brackets%29

Gelman

Possible duplicate of URL Encoding using C# – Selfappointed

You also can "convert" brackets manually with Replace method – Hafer

Answer 1

According to RFC 1738:

Thus, only alphanumerics, the special characters "$-_.+!*'(),", and
reserved characters used for their reserved purposes may be used
unencoded within a URL.

Neither HttpUtility.UrlEncode nor WebUtility.UrlEncode will encode those characters since the standard says the parentheses () can be used unencoded.

I don't know why the URL Encoder / Decoder you linked encodes them since it also lists them as as a character that can be used in a URL.

Samuella

I m making calls to a third party API over HTTP and passing a string in the parameters. This string is UTF-8 URL encoded. My API client is written in asp.net C# where as the API host is probably written in Java. When I have characters like parenthesis/brackets () in the string parameter, UTF-8 encoder does not encode them whereas the API host encodes them in %28 and %29 and I get incorrect response. Any suggestions how to fix this? – Gelman

The API has the following reference in the documentation docs.oracle.com/javase/1.5.0/docs/api/java/net/URLEncoder.html – Gelman

You could maybe look at this: #846987 – Samuella

Answer 2

Uri.EscapeDataString does what you want. See MSDN.

Ruel

Sorry It does not work. Tried this string str = "test(brackets)"; str = Uri.EscapeDataString(str); – Gelman

Strange. When I try "string result = Uri.EscapeDataString("test(brackets)");" the result is "test%28brackets%29". What value has str after EscapeDataString on your system? – Ruel

The string stays the same. It does not change – Gelman

The behaviour of Uri.EscapeDataString changed with .NET 4.5 to include RFC 3986 characters. – Samuella

@Dirk: Thanks for the info. Indeed I am targeting .NET 4.5. – Ruel

Tried, change from 4.0 to 4.5 in project properties does not work, new one 4.5 web app will work. A little strange. – Briggs

Answer 3

Uri.EscapeDataString will convert the string using the Uri standrards, which is not RFC 1738 conform.

RFC 1738 is an old URL standard.
I accomplished it by using FormUrlEncodedContent:

data = new List<KeyValuePair<string, string>>();
data.Add(new KeyValuePair<string, string>("key", "value"));

var payloadBody = await new FormUrlEncodedContent(data).ReadAsStringAsync();

If you don`t need a encoded URL body you probably need to trick arround with the key / value f.e. let the value empty.

Urson