Socket.Connected Property

Gets a value that indicates whether a Socket is connected to a remote host as of the last Send or Receive operation.

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

'Declaration
Public ReadOnly Property Connected As Boolean

Property Value

Type: System.Boolean
true if the Socket was connected to a remote resource as of the most recent operation; otherwise, false.

The Connected property gets the connection state of the Socket as of the last I/O operation. When it returns false, the Socket was either never connected, or is no longer connected.

The value of the Connected property reflects the state of the connection as of the most recent operation. If you need to determine the current state of the connection, make a nonblocking, zero-byte Send call. If the call returns successfully or throws a WAEWOULDBLOCK error code (10035), then the socket is still connected; otherwise, the socket is no longer connected.

If you call Connect on a User Datagram Protocol (UDP) socket, the Connected property always returns true; however, this action does not change the inherent connectionless nature of UDP.

The following code example connects to a remote endpoint, checks the Connected property, and checks the current state of the connection.

    ' .Connect throws an exception if unsuccessful
    client.Connect(anEndPoint)

    ' This is how you can determine whether a socket is still connected. 
    Dim blockingState As Boolean = client.Blocking
    Try 
        Dim tmp(0) As Byte

        client.Blocking = False
        client.Send(tmp, 0, 0)
        Console.WriteLine("Connected!")
    Catch e As SocketException
        ' 10035 == WSAEWOULDBLOCK 
        If e.NativeErrorCode.Equals(10035) Then
            Console.WriteLine("Still Connected, but the Send would block")
        Else
            Console.WriteLine("Disconnected: error code {0}!", e.NativeErrorCode)
        End If 
    Finally
        client.Blocking = blockingState
    End Try

    Console.WriteLine("Connected: {0}", client.Connected)

End Sub 'ConnectAndCheck

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2014 Microsoft