This documentation is archived and is not being maintained.

WebHeaderCollection.Set Method (String, String)

Sets the specified header to the specified value.

Namespace:  System.Net
Assembly:  System (in System.dll)

Public Overrides Sub Set ( _
	name As String, _
	value As String _
Dim instance As WebHeaderCollection 
Dim name As String 
Dim value As String

instance.Set(name, value)


Type: System.String

The header to set.

Type: System.String

The content of the header to set.


name is Nothing or Empty.


The length of value is greater than 65535.


name is a restricted header.


name or value contain invalid characters.

If the header specified in the header does not exist, the Set method inserts a new header into the list of header name/value pairs.

If the header specified in header is already present, value replaces the existing value.

The following example uses the Set method to set the value of an existing header.

    Public Shared Sub Main()

            'Create a web request for "". 
            Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create(""), HttpWebRequest)

            'Get the headers associated with the request. 
            Dim myWebHeaderCollection As WebHeaderCollection = myHttpWebRequest.Headers

            'Set the Cache-Control header in the request.
            myWebHeaderCollection.Set("Cache-Control", "no-cache")

            'Get the associated response for the above request. 
            Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)

	    Console.WriteLine ("Headers after 'Set' method is used on Cache-Control :")
            'Print the headers for the request.
       'Catch exception if trying to set a restricted header. 
        Catch e As ArgumentException
        Catch e As WebException
            If e.Status = WebExceptionStatus.ProtocolError Then
                Console.WriteLine("Status Code : {0}", CType(e.Response, HttpWebResponse).StatusCode)
                Console.WriteLine("Status Description : {0}", CType(e.Response, HttpWebResponse).StatusDescription)
                Console.WriteLine("Server : {0}", CType(e.Response, HttpWebResponse).Server)
            End If 
        Catch e As Exception
        End Try 
    End Sub 'Main
try {
   // Create a web request for S"".
   HttpWebRequest* myHttpWebRequest =
      dynamic_cast<HttpWebRequest*> (WebRequest::Create(S""));

   // Get the headers associated with the request.
   WebHeaderCollection* myWebHeaderCollection = myHttpWebRequest->Headers;

   // Set the Cache-Control header in the request.
   myWebHeaderCollection->Set(S"Cache-Control", S"no-cache");

   // Get the associated response for the above request.
   HttpWebResponse* myHttpWebResponse =
      dynamic_cast<HttpWebResponse*> (myHttpWebRequest->GetResponse());

   Console::WriteLine (S"Headers after 'Set' method is used on Cache-Control :");
   // Print the headers for the request.
// Catch exception if trying to set a restricted header.
catch(ArgumentException* e) {
   Console::WriteLine(S"ArgumentException is thrown. Message is : {0}", e->Message);
} catch (WebException* e) {
   Console::WriteLine(S"WebException is thrown. Message is : {0}", e->Message);
   if (e->Status == WebExceptionStatus::ProtocolError) {
      Console::WriteLine(S"Status Code : {0}", __box((dynamic_cast<HttpWebResponse*>(e->Response))->StatusCode));
      Console::WriteLine(S"Status Description : {0}",
      Console::WriteLine(S"Server : {0}",
} catch (Exception* e) {
   Console::WriteLine(S"Exception is thrown. Message is : {0}", e->Message);

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0