HttpServerUtility.UrlEncode Method

Definition

Namespace:

System.Web

Assembly:

System.Web.dll

Encodes a string for reliable HTTP transmission from the Web server to a client through the URL.

Overloads

UrlEncode(String)	URL-encodes a string and returns the encoded string.
UrlEncode(String, TextWriter)	URL-encodes a string and sends the resulting output to a TextWriter output stream.

Remarks

UrlEncode is a convenient way to access the HttpUtility.UrlEncode method at run time from an ASP.NET application. Internally, UrlEncode uses HttpUtility.UrlEncode to encode strings.

To encode or decode values outside of a web application, use the WebUtility class.

UrlEncode(String)

URL-encodes a string and returns the encoded string.

public:
 System::String ^ UrlEncode(System::String ^ s);

public string UrlEncode (string s);

member this.UrlEncode : string -> string

Public Function UrlEncode (s As String) As String

Parameters

s

String

The text to URL-encode.

Returns

String

The URL-encoded text.

Examples

The following example shows how to URL-encode a value that is used as a query string value of a hyperlink. The code resides in the code-behind file for a web page. The value to encode is hard-coded in this example only to simplify the example and show the type of value you might URL-encode. Typically, you would URL-encode a value that you received from the user or the request. NextPage refers to a HyperLink control.

public partial class _Default : Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string destinationURL = "http://www.contoso.com/default.aspx?user=test";

        NextPage.NavigateUrl = "~/Finish?url=" + Server.UrlEncode(destinationURL);
    }             
}

Public Class _Default
    Inherits Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        Dim destinationURL = "http://www.contoso.com/default.aspx?user=test"

        NextPage.NavigateUrl = "~/Finish?url=" + Server.UrlEncode(destinationURL)
    End Sub
End Class

The next example is similar to the previous example except it shows how to URL-encode a value from within a class that is not in the code-behind file.

public class SampleClass
{
    public string GetUrl()
    {
        string destinationURL = "http://www.contoso.com/default.aspx?user=test";

        return "~/Finish?url=" + HttpContext.Current.Server.UrlEncode(destinationURL);
    }
}

Public Class SampleClass
    Public Function GetUrl() As String
        Dim destinationURL = "http://www.contoso.com/default.aspx?user=test"

        Return "~/Finish?url=" + HttpContext.Current.Server.UrlEncode(destinationURL)
    End Function
End Class

Remarks

URL encoding ensures that all browsers will correctly transmit text in URL strings. Characters such as a question mark (?), ampersand (&), slash mark (/), and spaces might be truncated or corrupted by some browsers. As a result, these characters must be encoded in <a> tags or in query strings where the strings can be re-sent by a browser in a request string.

This method is a convenient way to access the HttpUtility.UrlEncode method at run time from an ASP.NET application. Internally, this method uses HttpUtility.UrlEncode to encode strings.

In the code-behind file for an ASP.NET web page, access an instance of the HttpServerUtility class through the Server property. In a class that is not in a code-behind file, use HttpContext.Current.Server to access an instance of the HttpServerUtility class.

Outside of a web application, use the WebUtility class to encode or decode values.

UrlEncode(String, TextWriter)

URL-encodes a string and sends the resulting output to a TextWriter output stream.

public:
 void UrlEncode(System::String ^ s, System::IO::TextWriter ^ output);

public void UrlEncode (string s, System.IO.TextWriter output);

member this.UrlEncode : string * System.IO.TextWriter -> unit

Public Sub UrlEncode (s As String, output As TextWriter)

Parameters

s

String

The text string to encode.

output

TextWriter

The TextWriter output stream that contains the encoded string.

Examples

The following example encodes a string for transmission by HTTP. It encodes the string named TestString, which contains the text "This is a <Test String>.", and copies it into the string named EncodedString as "This+is+a+%3cTest+String%3e.".

String TestString = "This is a <Test String>.";
StringWriter writer = new StringWriter();
Server.UrlEncode(TestString, writer);
String EncodedString = writer.ToString();

Dim TestString As String = "This is a <Test String>."
Dim writer As New StringWriter
Server.UrlEncode(TestString, writer)
Dim EncodedString As String = writer.ToString()
   

Remarks

URL encoding ensures that all browsers will correctly transmit text in URL strings. Characters such as a question mark (?), ampersand (&), slash mark (/), and spaces might be truncated or corrupted by some browsers. As a result, these characters must be encoded in <a> tags or in query strings where the strings can be re-sent by a browser in a request string.

UrlEncode is a convenient way to access the HttpUtility.UrlEncode method at run time from an ASP.NET application. Internally, UrlEncode uses HttpUtility.UrlEncode to encode strings.

To encode or decode values outside of a web application, use the WebUtility class.