TcpListener.Pending Method
Definition
Important
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Determines if there are pending connection requests.
public:
bool Pending();
public bool Pending ();
member this.Pending : unit -> bool
Public Function Pending () As Boolean
Returns
true
if connections are pending; otherwise, false
.
Exceptions
The listener has not been started with a call to Start().
Examples
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.
TcpListener^ tcpListener = gcnew TcpListener( 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 {0} on port number {1}",
IPAddress::Parse( ( (IPEndPoint^)(tcpListener->LocalEndpoint) )->Address->ToString() ),
( (IPEndPoint^)(tcpListener->LocalEndpoint) )->Port );
const int portNumber = 13;
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());
//Close the tcpListener and tcpClient instances
tcpClient.Close();
}
tcpListener.Stop();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
Try
Dim ipAddress As IPAddress = Dns.Resolve("localhost").AddressList(0)
Dim tcpListener As New TcpListener(ipAddress, portNumber)
tcpListener.Start()
' Use the Pending method to poll the underlying socket instance for client connection requests.
If Not tcpListener.Pending() Then
Console.WriteLine("Sorry, no connection requests have arrived")
Else
'Accept the pending client connection and return a TcpClient object initialized for communication.
Dim tcpClient As TcpClient = tcpListener.AcceptTcpClient()
' Using the RemoteEndPoint property.
Console.Write("I am listening for connections on ")
Console.Writeline(IPAddress.Parse(CType(tcpListener.LocalEndpoint, IPEndPoint).Address.ToString()))
Console.Write("on port number ")
Console.Write(CType(tcpListener.LocalEndpoint, IPEndPoint).Port.ToString())
Remarks
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.