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WebHeaderCollection.Add Method (String)

Inserts the specified header into the collection.

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

Public Sub Add ( _
	header As String _
Dim instance As WebHeaderCollection 
Dim header As String



Type: System.String

The header to add, with the name and value separated by a colon.


header is Nothing or Empty.


header does not contain a colon (:) character.

The length of value is greater than 65535.


The name part of header is Empty or contains invalid characters.


header is a restricted header that should be set with a property.


The value part of header contains invalid characters.


The length the string after the colon (:) is greater than 65535.

The header parameter must be specified in the format "name:value". If the specified header does not exist in the collection, a new header is added to the collection.

If the header specified in header is already present in the collection, the value part of the header is concatenated with the existing value.

The following example adds a name/value pair to a WebHeaderCollection using the Add Method.

    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

   	    Console.WriteLine("Configuring Webrequest to accept Danish and English language using 'Add' method")

	    'Add the Accept-Language header (for Danish) in the request.

            'Include English in the Accept-Langauge header. 
            myWebHeaderCollection.Add("Accept-Language","en;q" + ChrW(61) + "0.8")

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

            'Print the headers for the request.
        'Catch exception if trying to add 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;

   Console::WriteLine(S"Configuring Webrequest to accept Danish and English language using 'Add' method");

   //Add the Accept-Language header (for Danish) in the request.

   //Include English in the Accept-Langauge header.

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

   //Print the headers for the request.
//Catch exception if trying to add a restricted header.
catch(ArgumentException* e) {
} catch (WebException* e) {
   Console::WriteLine(S"\nWebException is thrown. \nMessage is : {0}", e->Message);
   if (e->Status == WebExceptionStatus::ProtocolError) {
      Console::WriteLine(S"Status Code : {0}", 
      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