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TcpListener.Pending Method

Determines if there are pending connection requests.

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

public bool Pending ()
public boolean Pending ()
public function Pending () : boolean

Return Value

true if connections are pending; otherwise, false.

Exception typeCondition

InvalidOperationException

The listener has not been started with a call to Start.

This non-blocking method determines if there are any pending connection requests. Because the AcceptSocket and AcceptTcpClient methods block execution until the Start method has queued an incoming connection request, the Pending method can be used to determine if connections are available before attempting to accept them.

The following code example checks the Pending method. If a connection request is waiting to be accepted, then a call to the AcceptTcpClient method is made.

        
try{
        // Use the Pending method to poll the underlying socket instance for client connection requests.
            IPAddress ipAddress = Dns.Resolve("localhost").AddressList[0];
         TcpListener tcpListener =  new TcpListener(ipAddress, portNumber); 
         tcpListener.Start();
         
          if (!tcpListener.Pending()) {

          Console.WriteLine("Sorry, no connection requests have arrived");
          
       }
       else{

             //Accept the pending client connection and return a TcpClient object initialized for communication.
             TcpClient tcpClient = tcpListener.AcceptTcpClient();
             // Using the RemoteEndPoint property.
             Console.WriteLine("I am listening for connections on " + 
                                         IPAddress.Parse(((IPEndPoint)tcpListener.LocalEndpoint).Address.ToString()) +
                                            "on port number " + ((IPEndPoint)tcpListener.LocalEndpoint).Port.ToString());


try {
    // Use the Pending method to poll the underlying socket instance
    // for client connection requests.
    IPAddress ipAddress = Dns.Resolve("localhost").get_AddressList()[0];
    TcpListener tcpListener = new TcpListener(ipAddress, portNumber);
    tcpListener.Start();

    if (!(tcpListener.Pending())) {
        Console.WriteLine("Sorry, no connection requests have arrived");
    }
    else {
        //Accept the pending client connection and return a TcpClient
        //object initialized for communication.
        TcpClient tcpClient = tcpListener.AcceptTcpClient();
        // Using the RemoteEndPoint property.
        Console.WriteLine("I am listening for connections on "
            + IPAddress.Parse(((IPEndPoint)
            (tcpListener.get_LocalEndpoint())).get_Address().ToString())
            + "on port number " + ((Int32)((IPEndPoint)
            (tcpListener.get_LocalEndpoint())).get_Port()).ToString());

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

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0
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