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SelectMode Enumeration

Defines the polling modes for the Socket.Poll method.

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

public enum SelectMode

Member nameDescription
Supported by the .NET Compact FrameworkSelectReadRead status mode.
Supported by the .NET Compact FrameworkSelectWriteWrite status mode.
Supported by the .NET Compact FrameworkSelectErrorError status mode.

The SelectMode enumeration defines the polling modes that can be passed to the Socket.Poll method. Use the SelectRead value to determine if a listening Socket has incoming connection requests. Use the SelectWrite value to determine if a Socket is writeable. Use the SelectError value to determine if there is an error condition present on the Socket. For explanations of writeability, readability, and the presence of error conditions, see the Socket.Poll method.

The following example checks the status of a Socket using all three SelectMode enumeration values. A call to Poll using the SelectWrite enumerated value should return true.

//Creates the Socket for sending data over TCP.
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream,
   ProtocolType.Tcp );

// Connects to host using IPEndPoint.
if (!s.Connected)
   strRetPage = "Unable to connect to host";
// Use the SelectWrite enumeration to obtain Socket status. 
 if(s.Poll(-1, SelectMode.SelectWrite)){
      Console.WriteLine("This Socket is writable.");
 else if (s.Poll(-1, SelectMode.SelectRead)){
 	   Console.WriteLine("This Socket is readable." );
 else if (s.Poll(-1, SelectMode.SelectError)){
      Console.WriteLine("This Socket has an error.");
//Creates the Socket for sending data over TCP.
Socket* s = new Socket(AddressFamily::InterNetwork, SocketType::Stream, ProtocolType::Tcp );

// Connects to host using IPEndPoint.
if (!s->Connected) {
    strRetPage = S"Unable to connect to host";
// Use the SelectWrite enumeration to obtain Socket status.
if (s->Poll(-1, SelectMode::SelectWrite)) {
    Console::WriteLine(S"This Socket is writable.");
} else if (s->Poll(-1, SelectMode::SelectRead)) {
    Console::WriteLine(S"This Socket is readable.");
} else if (s->Poll(-1, SelectMode::SelectError)) {
    Console::WriteLine(S"This Socket has an error.");

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, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

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, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0