C / C++ / MFC

<br />
		if (SUCCEEDED(AccessibleObjectFromPoint(pt, &pacc, &vtChild)))<br />
		{<br />
			BSTR bsName = NULL;<br />
			BSTR bsValue = NULL;<br />
			pacc->get_accName(vtChild, &bsName);<br />
			pacc->get_accValue(vtChild, &bsValue);<br />
		}<br />

#define _ATL_SIMPLEMAPENTRY ((ATL::_ATL_CREATORARGFUNC*)1)

George_George wrote:

I think ((ATL::_ATL_CREATORARGFUNC)1) should be enough, since _ATL_CREATORARGFUNC itself is defined to function pointer type. Why add an additional * here

typedef HRESULT (WINAPI _ATL_CREATORARGFUNC)(void* pv, REFIID riid, 
LPVOID* ppv, DWORD_PTR dw);

typedef int (MYFUN) (int x);
int square(int x) {return x*x;}

void main()
{
  MYFUN  p = square; // error C2072: 'p' : initialization of a function	
  MYFUN *p = square; // this is OK.
}

George_George wrote:

I have tried your sample, and it is correct. I found when we define a function type, we always use its pointer form/type (e.g. in your sample, using type MYFUNC*, other than type MYFUNC*).

George_George wrote:

So, why not use function pointer type other than function type directly?

George_George wrote:

how to use function type directly, other than define a function type, but using pointer to function type

class MyFunObject
{
	MYFUN * fun;
public:

	MyFunObject(MYFUN f){fun = &f;}
	int Invoke( int i ){ return (*fun)(i);}
};

int main()
{
	MyFunObject mfo(square);
	printf("%d\n",mfo.Invoke(4));
	getchar();

	return 0;
}

return (*fun)(i);}

MYFUN * fun;

typedef int (MYFUN) (int x);

template <class T>
class IMyContainer
{
public:
	virtual int add(T t)=0;
	virtual void remove(T t)=0;
};

class IMyFunContainer : public IMyContainer <MYFUN>
{
	virtual int Invoke(int iIndex, int arg)=0;
};