Visual Basic

Public Sub Start()
    Dim EP As New IPEndPoint(IPAddress.Any, Me.Port)
    Dim listener As New Socket(EP.AddressFamily, SocketType.Stream, ProtocolType.Tcp)
    listener.Bind(EP)
    listener.Listen(10)
    listener.BeginAccept(New AsyncCallback(AddressOf OnConnectRequest), listener)
End Sub

Private Sub OnConnectRequest(ByVal ar As IAsyncResult)
    Dim listener As Socket = DirectCast(ar.AsyncState, Socket)
    '(Adds connected client to a list)
    listener.BeginAccept(New AsyncCallback(AddressOf OnConnectRequest), listener)
End Sub

Public Sub Connect(ByVal port As Integer)
    Dim sock As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)
    Dim server As New IPEndPoint(IPAddress.Loopback, port)
    sock.BeginConnect(server, New AsyncCallback(AddressOf OnConnect), sock)
End Sub

Private Sub OnConnect(ByVal ar As IAsyncResult)
    Dim sock As Socket = DirectCast(ar.AsyncState, Socket)
    sock.EndConnect(ar) 'Exception is thrown here
    '(Handle connection)
End Sub

typedef struct 
{
        char tableName[256];
        char variableName[256];
        char value[256];
        long sheet;
        Enum_Data_Type varType;
} ITF_VariableType;