select

最新推荐文章于 2022-05-15 10:23:33 发布

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最新推荐文章于 2022-05-15 10:23:33 发布

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文章标签： sockets socket struct function null

本文链接：https://blog.youkuaiyun.com/helonSY/article/details/6255666

本文介绍了Windows套接字API中的select函数，详细解释了其参数意义，包括待检查读就绪、写就绪及错误状态的文件描述符集合，以及超时时间设置。并说明了返回值的含义，包括就绪描述符的数量、超时情况及错误处理。

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int select( __in int nfds, __inout fd_set *readfds, __inout fd_set *writefds, __inout fd_set *exceptfds, __in const struct timeval *timeout ); Parameters nfds [in] Ignored. The nfds parameter is included only for compatibility with Berkeley sockets. readfds [in, out] An optional pointer to a set of sockets to be checked for readability. writefds [in, out] An optional pointer to a set of sockets to be checked for writability. exceptfds [in, out] An optional pointer to a set of sockets to be checked for errors. timeout [in] The maximum time for select to wait, provided in the form of a TIMEVAL structure. Set the timeout parameter to null for blocking operations. Return Value The select function returns the total number of socket handles that are ready and contained in the fd_set structures, zero if the time limit expired, or SOCKET_ERROR if an error occurred. If the return value is SOCKET_ERROR, WSAGetLastError can be used to retrieve a specific error code.

详情见：http://msdn.microsoft.com/zh-cn/library/ms740141(v=VS.85).aspx