WebHeaderCollection.Add Method (String)


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Inserts the specified header into the collection.

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

public void Add(
	string header


Type: System.String

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

Exception Condition

header is null 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.

try {
	//Create a web request for "www.msn.com".
 	HttpWebRequest myHttpWebRequest = (HttpWebRequest) WebRequest.Create("http://www.msn.com");

	//Get the headers associated with the request.
	WebHeaderCollection myWebHeaderCollection = 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. 

	//Get the associated response for the above request.
 	HttpWebResponse myHttpWebResponse = (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("\nWebException is thrown. \nMessage is :" + e.Message);
	if(e.Status == WebExceptionStatus.ProtocolError) {
		Console.WriteLine("Status Code : {0}", ((HttpWebResponse)e.Response).StatusCode);
		Console.WriteLine("Status Description : {0}", ((HttpWebResponse)e.Response).StatusDescription);
		Console.WriteLine("Server : {0}", ((HttpWebResponse)e.Response).Server);
catch(Exception e) {
	Console.WriteLine("Exception is thrown. Message is :" + e.Message);

.NET Framework
Available since 1.1
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