NetworkChange Class

Allows applications to receive notification when the Internet Protocol (IP) address of a network interface, also called a network card or adapter, changes.

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

public sealed class NetworkChange

The NetworkChange class provides address change notification by raising NetworkAddressChanged events. An interface address can change for many reasons, such as a disconnected network cable, moving out of range of a wireless Local Area Network, or hardware failure.

To receive notification, you must identify your application's event handlers, which are one or more methods that perform your application-specific tasks each time the event is raised. To have a NetworkChange object call your event-handling methods when a NetworkAddressChanged event occurs, you must associate the methods with a NetworkAddressChangedEventHandler delegate, and add this delegate to the event.

The following code example listens for address changes and displays the status of network interfaces when a NetworkAddressChanged event occurs.

using System;
using System.Net;
using System.Net.NetworkInformation;

namespace Examples.Net.AddressChanges
{
    public class NetworkingExample
    {
        public static void Main()
        {
            NetworkChange.NetworkAddressChanged += new 
            NetworkAddressChangedEventHandler(AddressChangedCallback);
            Console.WriteLine("Listening for address changes. Press any key to exit.");
            Console.ReadLine();
        }
        static void AddressChangedCallback(object sender, EventArgs e)
        {

            NetworkInterface[] adapters = NetworkInterface.GetAllNetworkInterfaces();
            foreach(NetworkInterface n in adapters)
            {
                Console.WriteLine("   {0} is {1}", n.Name, n.OperationalStatus);
            }
        }
    }
}
#using <mscorlib.dll>
#using <System.dll>
using namespace System;
using namespace System::Net;
using namespace System::Net::NetworkInformation;

void AddressChangedCallback(Object* /*sender*/, EventArgs* /*e*/)
{

    NetworkInterface* adapters[] = NetworkInterface::GetAllNetworkInterfaces();
    System::Collections::IEnumerator* myEnum = adapters->GetEnumerator();
    while (myEnum->MoveNext())
    {
        NetworkInterface* n = __try_cast<NetworkInterface*>(myEnum->Current);
        Console::WriteLine(S"   {0} is {1}", n->Name, __box(n->OperationalStatus));
    }
}

int main()
{
    NetworkChange::NetworkAddressChanged += new 
        NetworkAddressChangedEventHandler(AddressChangedCallback);
    Console::WriteLine(S"Listening for address changes. Press any key to exit.");
    Console::ReadLine();
}

System.Object
  System.Net.NetworkInformation.NetworkChange

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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

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
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