The return value is zero if the operation was successful. Otherwise, the value SOCKET_ERROR is returned, and a specific error number is available in lpErrno.

The following table shows the possible error codes.

This function is used to report network events that have occurred for the indicated socket since the last invocation of this function. It is intended for use in conjunction with WSPEventSelect, which associates an event object with one or more network events. Recording of network events commences when WSPEventSelectis called with a nonzero lNetworkEventsparameter and remains in effect until another call is made to WSPEventSelectwith the lNetworkEventsparameter set to zero.

This function only reports network activity and errors nominated through WSPEventSelect. See the description of WSPSelectto find out how this function reports network activity and errors.

The socket's internal record of network events is copied to the structure referenced by lpNetworkEvents, after which the internal network events record is cleared. If hEventObjectis non-NULL, the indicated event object is also reset. The Windows Sockets provider guarantees that the operations of copying the network event record, clearing it, and resetting any associated event object are atomic, such that the next occurrence of a nominated network event will cause the event object to become set. In the case of this function returning SOCKET_ERROR, the associated event object is not reset and the record of network events is not cleared.

The following code sample shows how the WSANETWORKEVENTSstructure is defined.

	Copy Code
typedef struct _WSANETWORKEVENTS { long lNetworkEvents; int iErrorCode[FD_MAX_EVENTS]; } WSANETWORKEVENTS, FAR * LPWSANETWORKEVENTS;

The lNetworkEventmember of the structure indicates which of the FD_XXX network events have occurred. The iErrorCodearray is used to contain any associated error codes, with array index corresponding to the position of event bits in lNetworkEvents. The identifiers such as FD_READ_BIT and FD_WRITE_BIT can be used to index the iErrorCodearray.

Note that only those elements of the iErrorCodearray are set that correspond to the bits set in lNetworkEventsmember. Other members are not modified (this is important for backward compatibility with the Windows Socket 2 SPI clients that are not aware of new FD_ROUTING_INTERFACE_CHANGE and FD_ADDRESS_LIST_CHANGE events).

The following tables show the error codes that can be returned along with the respective network event.

Event: FD_CONNECT

Event: FD_CLOSE

Event: FD_READ

Event: FD_WRITE

Event: FD_OOB

Event: FD_ACCEPT

Event: FD_ADDRESS_LIST_CHANGE

Event: FD_ROUTING_INTERFACE_CHANGE