.NET Framework Class Library
TcpClient Class

Provides client connections for TCP network services.

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

Syntax

Visual Basic (Declaration)
Public Class TcpClient
    Implements IDisposable
Visual Basic (Usage)
Dim instance As TcpClient
C#
public class TcpClient : IDisposable
C++
public ref class TcpClient : IDisposable
J#
public class TcpClient implements IDisposable
JScript
public class TcpClient implements IDisposable
Remarks

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.

Example

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();
}
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();
}
J#
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 = (Int32)13000;
        TcpClient client = new TcpClient(server, (int)port);

        // Translate the passed message into ASCII and store
        // it as a Byte array.
        System.Byte data[] = (System.Byte[])
            System.Text.Encoding.get_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((ubyte[])data, 0, data.length);
        Console.WriteLine("Sent: {0}", message);

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

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

        // Read the first batch of the TcpServer response bytes.
        Int32 bytes = (Int32)stream.Read((ubyte[])data, 0, data.length);
        responseData = System.Text.Encoding.get_ASCII().GetString(
            (ubyte[])data, 0, (int)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();
} //Connect
.NET Framework Security

  • SocketPermission  to establish an outgoing connection or accept an incoming request.
Inheritance Hierarchy

System.Object
  System.Net.Sockets.TcpClient
Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Platforms

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

Version Information

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0
See Also

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