TcpClient Class
.NET Framework Class Library
TcpClient Class

Provides client connections for TCP network services.

Namespace:  System.Net.Sockets
Assembly:  System (in System.dll)
Visual Basic (Declaration)
Public Class TcpClient _
    Implements IDisposable
Visual Basic (Usage)
Dim instance As TcpClient
C#
public class TcpClient : IDisposable
Visual C++
public ref class TcpClient : IDisposable
JScript
public class TcpClient implements IDisposable

The TcpClient class provides simple methods for connecting, sending, and receiving stream data over a network in synchronous blocking mode.

In order for TcpClient to connect and exchange data, a TcpListener or Socket created with the TCP ProtocolType must be listening for incoming connection requests. You can connect to this listener in one of the following two ways:

  • Create a TcpClient and call one of the three available Connect methods.

  • Create a TcpClient using the host name and port number of the remote host. This constructor will automatically attempt a connection.

NoteNote:

If you want to send connectionless datagrams in synchronous blocking mode, use the UdpClient class.

Notes to Inheritors:

To send and receive data, use the GetStream method to obtain a NetworkStream. Call the Write and Read methods of the NetworkStream to send and receive data with the remote host. Use the Close method to release all resources associated with the TcpClient.

The following code example establishes a TcpClient connection.

Visual Basic
Shared Sub Connect(server As [String], message As [String])
   Try
      ' Create a TcpClient.
      ' Note, for this client to work you need to have a TcpServer 
      ' connected to the same address as specified by the server, port
      ' combination.
      Dim port As Int32 = 13000
      Dim client As New TcpClient(server, port)

      ' Translate the passed message into ASCII and store it as a Byte array.
      Dim data As [Byte]() = System.Text.Encoding.ASCII.GetBytes(message)

      ' Get a client stream for reading and writing.
      '  Stream stream = client.GetStream();
      Dim stream As NetworkStream = client.GetStream()

      ' Send the message to the connected TcpServer. 
      stream.Write(data, 0, data.Length)

      Console.WriteLine("Sent: {0}", message)

      ' Receive the TcpServer.response.
      ' Buffer to store the response bytes.
      data = New [Byte](256) {}

      ' String to store the response ASCII representation.
      Dim responseData As [String] = [String].Empty

      ' Read the first batch of the TcpServer response bytes.
      Dim bytes As Int32 = stream.Read(data, 0, data.Length)
      responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes)
      Console.WriteLine("Received: {0}", responseData)

      ' Close everything.
      stream.Close()
      client.Close()
   Catch e As ArgumentNullException
      Console.WriteLine("ArgumentNullException: {0}", e)
   Catch e As SocketException
      Console.WriteLine("SocketException: {0}", e)
   End Try

   Console.WriteLine(ControlChars.Cr + " Press Enter to continue...")
   Console.Read()
End Sub 'Connect
C#
static void Connect(String server, String message) 
{
  try 
  {
    // Create a TcpClient.
    // Note, for this client to work you need to have a TcpServer 
    // connected to the same address as specified by the server, port
    // combination.
    Int32 port = 13000;
    TcpClient client = new TcpClient(server, port);

    // Translate the passed message into ASCII and store it as a Byte array.
    Byte[] data = System.Text.Encoding.ASCII.GetBytes(message);         

    // Get a client stream for reading and writing.
   //  Stream stream = client.GetStream();

    NetworkStream stream = client.GetStream();

    // Send the message to the connected TcpServer. 
    stream.Write(data, 0, data.Length);

    Console.WriteLine("Sent: {0}", message);         

    // Receive the TcpServer.response.

    // Buffer to store the response bytes.
    data = new Byte[256];

    // String to store the response ASCII representation.
    String responseData = String.Empty;

    // Read the first batch of the TcpServer response bytes.
    Int32 bytes = stream.Read(data, 0, data.Length);
    responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
    Console.WriteLine("Received: {0}", responseData);         

    // Close everything.
    stream.Close();         
    client.Close();         
  } 
  catch (ArgumentNullException e) 
  {
    Console.WriteLine("ArgumentNullException: {0}", e);
  } 
  catch (SocketException e) 
  {
    Console.WriteLine("SocketException: {0}", e);
  }

  Console.WriteLine("\n Press Enter to continue...");
  Console.Read();
}
Visual C++
void Connect( String^ server, String^ message )
{
   try
   {
      // Create a TcpClient.
      // Note, for this client to work you need to have a TcpServer 
      // connected to the same address as specified by the server, port
      // combination.
      Int32 port = 13000;
      TcpClient^ client = gcnew TcpClient( server,port );

      // Translate the passed message into ASCII and store it as a Byte array.
      array<Byte>^data = Text::Encoding::ASCII->GetBytes( message );

      // Get a client stream for reading and writing.
      //  Stream stream = client->GetStream();

      NetworkStream^ stream = client->GetStream();

      // Send the message to the connected TcpServer. 
      stream->Write( data, 0, data->Length );

      Console::WriteLine( "Sent: {0}", message );

      // Receive the TcpServer::response.

      // Buffer to store the response bytes.
      data = gcnew array<Byte>(256);

      // String to store the response ASCII representation.
      String^ responseData = String::Empty;

      // Read the first batch of the TcpServer response bytes.
      Int32 bytes = stream->Read( data, 0, data->Length );
      responseData = Text::Encoding::ASCII->GetString( data, 0, bytes );
      Console::WriteLine( "Received: {0}", responseData );

      // Close everything.
      client->Close();
   }
   catch ( ArgumentNullException^ e ) 
   {
      Console::WriteLine( "ArgumentNullException: {0}", e );
   }
   catch ( SocketException^ e ) 
   {
      Console::WriteLine( "SocketException: {0}", e );
   }

   Console::WriteLine( "\n Press Enter to continue..." );
   Console::Read();
}
  • SocketPermission 

    Permission to establish an outgoing connection or accept an incoming request.

System..::.Object
  System.Net.Sockets..::.TcpClient
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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
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