INVALID_SOCKET的值

(2011-06-26 15:06:45)

标签：

杂谈

INVALID_SOCKET的值不是-1，原因参考basetsd.h和WinSock2.h：

typedef _W64 unsigned int UINT_PTR, *PUINT_PTR;

typedef UINT_PTR SOCKET;

#define INVALID_SOCKET (SOCKET)(~0)

(~0)的值为-1；

(SOCKET)(~0)的值为：十六进制0xFFFFFFFF（十进制4294967295）。

To abort a connection, release a socket handle, and discard data pending for writing, do:

closesocket(sock);
sock = INVALID_SOCKET; // do not make further use of sock.

To flush a sock handle, gracefully close the socket, and release the socket handle in the
background:

DisconnectEx(sock, NULL, 0, 0); // retrieve this function pointer with WSAIoctl(WSAID_DISCONNECTEX).
closesocket(sock);
sock = INVALID_SOCKET; // do not make further use of sock.

http://msdn.microsoft.com/en-us/library/ms737582(VS.85).aspx