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HttpListenerPrefixCollection::Add Method

Adds a Uniform Resource Identifier (URI) prefix to the collection.

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

virtual void Add(
	String^ uriPrefix
) sealed


Type: System::String
A String that identifies the URI information that is compared in incoming requests. The prefix must be terminated with a forward slash ("/").




uriPrefix is nullptr.


uriPrefix does not use the http:// or https:// scheme. These are the only schemes supported for HttpListener objects.


uriPrefix is not a correctly formatted URI prefix. Make sure the string is terminated with a "/".


The HttpListener associated with this collection is closed.


A Windows function call failed. Check the exception's ErrorCode property to determine the cause of the exception. This exception is thrown if another HttpListener has already added the prefix uriPrefix.

This method adds a URI prefix to the set of prefixes managed by the associated HttpListener object. When checking uriPrefix to ensure it is valid, case is ignored.

A URI prefix string is composed of a scheme (http or https), a host, an optional port, and an optional path, for example, "". The prefix must be terminated with a forward slash ("/"). The HttpListener with the prefix that most closely matches a requested URI responds to the request. Multiple HttpListener objects cannot add the same prefix. An HttpListenerException exception is thrown if an HttpListener adds a prefix that is already in use.

When a port is specified, the host element can be replaced with "*" to indicate that the HttpListener accepts requests sent to the port if the requested URI does not match any other prefix. For example, to receive all requests sent to port 8080 when the requested URI is not handled by any other HttpListener, the prefix is "http://*:8080/". Similarly, to specify that the HttpListener accepts all requests sent to a port, replace the host element with the "+" character, "https://+:8080/". The "*" and "+" characters can be present in prefixes that include paths.

The following code example creates an HttpListener and adds user-specified prefixes to its HttpListenerPrefixCollection.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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