可不可以通过recv的返回值来判断tcp连接是否断开？

[gohappy_1999]

各位说说

[gohappy_1999]

补充一下：SOCKET为阻塞模式

[快乐鹦鹉]

If no error occurs, recv returns the number of bytes received. If the connection has been gracefully closed, the return value is zero. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.

因此，当返回值为0时，认为tcp连接已经断开。

[gohappy_1999]

那么连接端开时一定返回0吗，连接断开可能是异常断开，也可能是正常关闭

[gohappy_1999]

up

[DentistryDoctor]

WSAGetLastError();

[bluekite]

WSAGetLastError() == 10054

在這個論壇上近期也有類似的帖子, 你找一下.

[nuaawenlin]

可以的

[ghxmagic]

正如上面所说的,如何recv函数返回0就是发生通讯失败了.你可以在这种情况下用shutdown函数进行确认.
......
else if (rcved_len == 0)
{
int iLastErr = 0;
iShutdown = shutdown(*pFd, 0);
/*Begin OS dependent*/
#ifdef _WIN32
iLastErr = WSAGetLastError();
if ( iShutdown == SOCKET_ERROR
&& (iLastErr == WSAENETDOWN || iLastErr == WSAENOTCONN) )
{
errno = iLastErr + ERRNO_MAX;
#else
if ( iShutdown == -1
&& errno == ENOTCONN )
{
#endif
/*End OS dependent*/
/* communication failed */
pErrMsg->ucErrMsg = PMONTHRE_ERR_151_COMM_FAILED;
}
else
{
pErrMsg->ucErrMsg = PMONTHRE_ERR_900_SYSTEMCALL_FAILED;
}

strcpy(pErrMsg->szFuncName, "recv");
pErrMsg->iErrNo = errno;
pErrMsg->iDetailCode = _ID_PMONThreMsgRecv | 0x00000006;

goto l_error;
}
......