首先 这两个函数 有这样的对应关系：

BOOL WINAPI GetQueuedCompletionStatus(  _In_   HANDLE CompletionPort,  _Out_  LPDWORD lpNumberOfBytes,  _Out_  PULONG_PTR lpCompletionKey,  _Out_  LPOVERLAPPED *lpOverlapped,  _In_   DWORD dwMilliseconds);BOOL WINAPI PostQueuedCompletionStatus(  _In_      HANDLE CompletionPort,  _In_      DWORD dwNumberOfBytesTransferred,  _In_      ULONG_PTR dwCompletionKey,  _In_opt_  LPOVERLAPPED lpOverlapped);

CompletionPort [in]A handle to an I/O completion port to which the I/O completion packet is to be posted.dwNumberOfBytesTransferred [in]The value to be returned through the lpNumberOfBytesTransferredparameter of the GetQueuedCompletionStatus function.dwCompletionKey [in]The value to be returned through the lpCompletionKey parameter of theGetQueuedCompletionStatus function.lpOverlapped [in, optional]The value to be returned through the lpOverlapped parameter of theGetQueuedCompletionStatus function.

此间主要有两个问题没有理清楚：

1.没有想明白 第三个参数 _In_  ULONG_PTR dwCompletionKey, 可以是自定义的数据类型， 例如int， 我的工程中传值为 iocp_api::Accept(=2), 即简单的 int 数值 值为 2， 那么在

BOOL WINAPI GetQueuedCompletionStatus(  _In_   HANDLE CompletionPort,  _Out_  LPDWORD lpNumberOfBytes,  _Out_  PULONG_PTR lpCompletionKey,  _Out_  LPOVERLAPPED *lpOverlapped,  _In_   DWORD dwMilliseconds);
函数 的 _Out_  PULONG_PTR lpCompletionKey 的值就会是 2， 我的问题出在“进行普通的 GetQueuedCompletionStatus() 处理时， 参数是返回地址指针类型“ ， 没有意识到 该指针的值 就是 0x00000002 

2.没有注意到 两个函数的 微妙非堆成区别：

BOOL WINAPI GetQueuedCompletionStatus( ...,  _Out_  LPOVERLAPPED *lpOverlapped, ... );

BOOL WINAPI PostQueuedCompletionStatus( ...,  _In_opt_  LPOVERLAPPED lpOverlapped );

GetQueuedCompletionStatus() 要求的是 LPOVERLAPPED * 
而 PostQueuedCompletionStatus() 是 LPOVERLAPPED