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Call this member function to establish a connection to an unconnected stream or datagram socket.

BOOL Connect( 
   LPCTSTR lpszHostAddress, 
   UINT nHostPort  
BOOL Connect( 
   const SOCKADDR* lpSockAddr, 
   int nSockAddrLen  


The network address of the socket to which this object is connected: a machine name such as "ftp.microsoft.com", or a dotted number such as "".


The port identifying the socket application.


A pointer to a SOCKADDR structure that contains the address of the connected socket.


The length of the address in lpSockAddr in bytes.

Nonzero if the function is successful; otherwise 0, and a specific error code can be retrieved by calling GetLastError. If this indicates an error code of WSAEWOULDBLOCK, and your application is using the overridable callbacks, your application will receive an OnConnect message when the connect operation is complete. The following errors apply to this member function:

  • WSANOTINITIALISED   A successful AfxSocketInit must occur before using this API.

  • WSAENETDOWN   The Windows Sockets implementation detected that the network subsystem failed.

  • WSAEADDRINUSE   The specified address is already in use.

  • WSAEINPROGRESS   A blocking Windows Sockets call is in progress.

  • WSAEADDRNOTAVAIL   The specified address is not available from the local machine.

  • WSAEAFNOSUPPORT   Addresses in the specified family cannot be used with this socket.

  • WSAECONNREFUSED   The attempt to connect was rejected.

  • WSAEDESTADDRREQ   A destination address is required.

  • WSAEFAULT   The nSockAddrLen argument is incorrect.

  • WSAEINVAL   Invalid host address.

  • WSAEISCONN   The socket is already connected.

  • WSAEMFILE   No more file descriptors are available.

  • WSAENETUNREACH   The network cannot be reached from this host at this time.

  • WSAENOBUFS   No buffer space is available. The socket cannot be connected.

  • WSAENOTSOCK   The descriptor is not a socket.

  • WSAETIMEDOUT   Attempt to connect timed out without establishing a connection.

  • WSAEWOULDBLOCK   The socket is marked as nonblocking and the connection cannot be completed immediately.

If the socket is unbound, unique values are assigned to the local association by the system, and the socket is marked as bound. Note that if the address field of the name structure is all zeroes, Connect will return zero. To get extended error information, call the GetLastError member function.

For stream sockets (type SOCK_STREAM), an active connection is initiated to the foreign host. When the socket call completes successfully, the socket is ready to send/receive data.

For a datagram socket (type SOCK_DGRAM), a default destination is set, which will be used on subsequent Send and Receive calls.

Header: afxsock.h

© 2015 Microsoft