How to encode the plus (+) symbol in a URL - asp.net

Question

The URL link below will open a new Google mail window. The problem I have is that Google replaces all the plus (+) signs in the email body with blank space. It looks like it only happens with the + sign. How can I remedy this? (I am working on a ASP.NET web page.)
https://mail.google.com/mail?view=cm&tf=0&to=someemail#somedomain.com&su=some subject&body=Hi there+Hello there
(In the body email, "Hi there+Hello there" will show up as "Hi there Hello there")

Answer 1

The + character has a special meaning in [the query segment of] a URL => it means whitespace: . If you want to use the literal + sign there, you need to URL encode it to %2b:
body=Hi+there%2bHello+there
Here's an example of how you could properly generate URLs in .NET:
var uriBuilder = new UriBuilder("https://mail.google.com/mail");
var values = HttpUtility.ParseQueryString(string.Empty);
values["view"] = "cm";
values["tf"] = "0";
values["to"] = "someemail#somedomain.com";
values["su"] = "some subject";
values["body"] = "Hi there+Hello there";
uriBuilder.Query = values.ToString();
Console.WriteLine(uriBuilder.ToString());
The result:
https://mail.google.com:443/mail?view=cm&tf=0&to=someemail%40somedomain.com&su=some+subject&body=Hi+there%2bHello+there

Answer 2

If you want a plus + symbol in the body you have to encode it as 2B.
For example:
Try this

Answer 3

In order to encode a + value using JavaScript, you can use the encodeURIComponent function.
Example:
var url = "+11";
var encoded_url = encodeURIComponent(url);
console.log(encoded_url)

Answer 4

It's safer to always percent-encode all characters except those defined as "unreserved" in RFC-3986.
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
So, percent-encode the plus character and other special characters.
The problem that you are having with pluses is because, according to RFC-1866 (HTML 2.0 specification), paragraph 8.2.1. subparagraph 1., "The form field names and values are escaped: space characters are replaced by `+', and then reserved characters are escaped"). This way of encoding form data is also given in later HTML specifications, look for relevant paragraphs about application/x-www-form-urlencoded.

Answer 5

Just to add this to the list:
Uri.EscapeUriString("Hi there+Hello there") // Hi%20there+Hello%20there
Uri.EscapeDataString("Hi there+Hello there") // Hi%20there%2BHello%20there
See https://stackoverflow.com/a/34189188/98491
Usually you want to use EscapeDataString which does it right.

Answer 6

Generally if you use .NET API's - new Uri("someproto:with+plus").LocalPath or AbsolutePath will keep plus character in URL. (Same "someproto:with+plus" string)
but Uri.EscapeDataString("with+plus") will escape plus character and will produce "with%2Bplus".
Just to be consistent I would recommend to always escape plus character to "%2B" and use it everywhere - then no need to guess who thinks and what about your plus character.
I'm not sure why from escaped character '+' decoding would produce space character ' ' - but apparently it's the issue with some of components.