C / C++ / MFC

Eric__V wrote:

It seems that when an instance of a pure virtual base class is created, an instance of its child is in fact created.

Eric__V wrote:

An observation. VS finds it impossible to debug step into any functions of the _child instance.

Eric__V wrote:

Further question. What if you have two descendents from _base. How does the compiler know which one to instantiate?

Eric__V wrote:

The code creates an instance of _base and uses it.

class Onion
{
public:
	virtual void f( ) = 0;
};

class Tata : public Onion
{
	virtual void f();
};

Tata tata;

CPallini wrote:

would generate a compiler error...

Vaclav_Sal wrote:

What are the basic benefits of using mmioxxxx “file” functions as opposed to “plain “ MFC CFile?

Mark Salsbery
Microsoft MVP - Visual C++

// OVERLAPPEDOP_xxx used for overlapped IO

#define OVERLAPPEDOP_NOOP				0
#define OVERLAPPEDOP_SOCKACCEPT			1	// CompletionKey = SOCKET, pData  = 0
#define OVERLAPPEDOP_SOCKSEND			2	// CompletionKey = SOCKET, pData  = NETCOMMPACKET*
#define OVERLAPPEDOP_SOCKRECVHEADER		3	// CompletionKey = SOCKET, pData  = NETPACKETHEADER*
#define OVERLAPPEDOP_SOCKRECVPACKET		4	// CompletionKey = SOCKET, pData  = NETCOMMPACKET*
#define OVERLAPPEDOP_EXITTHREAD			5	// CompletionKey = 0

// MANAGEROP_xxx used for server manager thread operations

#define MANAGEROP_ADDCLIENTCONNECTION		1	// pData  = NEWUSERSOCKETINFO*
#define MANAGEROP_REMOVECLIENTCONNECTION	2	// lParam1 = CClientConnection*
#define MANAGEROP_REMOVEIOCPTHREAD			3	// lParam1 = CIOCPHandlerThread*
#define MANAGEROP_BROADCASTMESSAGE			4	// lParam1 = NETCOMMPACKETLITE* (alloc'd as BYTE*), lParam2 = CClientConnection* client to exclude

//-------------------------------------------------------------------------


#pragma pack( push, SRVRMGR_OVERLAPPEDpack, 1 )
//-------------------------------------------------------------------------
struct SRVRMGR_OVERLAPPED
//-------------------------------------------------------------------------
{
	OVERLAPPED Overlapped;

	DWORD dwOpCode;    // OVERLAPPEDOP_xxxx and MANAGEROP_xxxx codes defined above
	CClientConnection *pClientConnection;
	LPARAM	lParam1;
	LPARAM	lParam2;
	DWORD dwDataLength;
	DWORD dwDataLengthProcessed;
	BYTE *pData;

	SRVRMGR_OVERLAPPED()  {memset(this, 0, sizeof(SRVRMGR_OVERLAPPED));}
};
#pragma pack( pop, SRVRMGR_OVERLAPPEDpack)
typedef CTypedPtrList<CPtrList, SRVRMGR_OVERLAPPED*> SRVRMGR_OVERLAPPEDPtrList;

Mark Salsbery
Microsoft MVP - Visual C++