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// 
// IUnknown.cpp 
// To compile use: cl IUnknown.cpp UUID.lib 
// 
#include  
#include  
 
void trace(const char* msg) { cout << msg << endl ;} 
 
 
// Interfaces 
interface IX : IUnknown 
{ 
	virtual void __stdcall Fx() = 0 ; 
} ; 
 
interface IY : IUnknown 
{ 
	virtual void __stdcall Fy() = 0 ; 
} ; 
 
interface IZ : IUnknown 
{ 
	virtual void __stdcall Fz() = 0 ; 
} ; 
 
// Forward references for GUIDs 
extern const IID IID_IX ; 
extern const IID IID_IY ; 
extern const IID IID_IZ ; 
 
// 
// Component 
// 
class CA : public IX, 
           public IY 
{ 
	//IUnknown implementation 
	virtual HRESULT __stdcall QueryInterface(const IID& iid, void** ppv) ;			 
	virtual ULONG __stdcall AddRef() { return 0 ;} 
	virtual ULONG __stdcall Release() { return 0 ;} 
 
	// Interface IX implementation 
	virtual void __stdcall Fx() { cout << "Fx" << endl ;} 
 
	// Interface IY implementation 
	virtual void __stdcall Fy() { cout << "Fy" << endl ;} 
} ; 
 
HRESULT __stdcall CA::QueryInterface(const IID& iid, void** ppv) 
{ 	 
	if (iid == IID_IUnknown) 
	{ 
		trace("QueryInterface: Return pointer to IUnknown.") ; 
		*ppv = static_cast(this) ; 
	} 
	else if (iid == IID_IX) 
	{ 
		trace("QueryInterface: Return pointer to IX.") ; 
		*ppv = static_cast(this) ; 
	} 
	else if (iid == IID_IY) 
	{ 
		trace("QueryInterface: Return pointer to IY.") ; 
		*ppv = static_cast(this) ; 
	} 
	else 
	{  	    
		trace("QueryInterface: Interface not supported.") ; 
		*ppv = NULL ; 
		return E_NOINTERFACE ; 
	} 
	reinterpret_cast(*ppv)->AddRef() ; // See Chapter 4. 
	return S_OK ; 
} 
 
// 
// Creation function 
// 
IUnknown* CreateInstance() 
{ 
	IUnknown* pI = static_cast(new CA) ; 
	pI->AddRef() ; 
	return pI ; 
} 
 
// 
// IIDs 
// 
// {32bb8320-b41b-11cf-a6bb-0080c7b2d682} 
static const IID IID_IX =  
	{0x32bb8320, 0xb41b, 0x11cf, 
	{0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ; 
 
// {32bb8321-b41b-11cf-a6bb-0080c7b2d682} 
static const IID IID_IY =  
	{0x32bb8321, 0xb41b, 0x11cf, 
	{0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ; 
 
// {32bb8322-b41b-11cf-a6bb-0080c7b2d682} 
static const IID IID_IZ =  
	{0x32bb8322, 0xb41b, 0x11cf, 
	{0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ; 
 
// 
// Client 
// 
int main() 
{ 
	HRESULT hr ; 
 
	trace("Client:         Get an IUnknown pointer.") ; 
	IUnknown* pIUnknown = CreateInstance() ; 
 
    
	trace("Client:         Get interface IX.") ; 
 
	IX* pIX = NULL ;  
	hr = pIUnknown->QueryInterface(IID_IX, (void**)&pIX) ; 
	if (SUCCEEDED(hr)) 
	{ 
		trace("Client:         Succeeded getting IX.") ; 
		pIX->Fx() ;          // Use interface IX. 
	} 
 
 
	trace("Client:         Get interface IY.") ; 
 
	IY* pIY = NULL ; 
	hr = pIUnknown->QueryInterface(IID_IY, (void**)&pIY) ; 
	if (SUCCEEDED(hr)) 
	{ 
		trace("Client:         Succeeded getting IY.") ; 
		pIY->Fy() ;          // Use interface IY. 
	} 
 
 
	trace("Client:         Ask for an unsupported interface.") ; 
 
	IZ* pIZ = NULL ; 
	hr = pIUnknown->QueryInterface(IID_IZ, (void**)&pIZ) ; 
	if (SUCCEEDED(hr)) 
	{ 
		trace("Client:         Succeeded in getting interface IZ.") ; 
		pIZ->Fz() ; 
	} 
	else 
	{ 
		trace("Client:         Could not get interface IZ.") ; 
	} 
 
 
	trace("Client:         Get interface IY from interface IX.") ; 
 
	IY* pIYfromIX = NULL ; 
	hr = pIX->QueryInterface(IID_IY, (void**)&pIYfromIX) ; 
	if (SUCCEEDED(hr)) 
	{	 
		trace("Client:         Succeeded getting IY.") ; 
		pIYfromIX->Fy() ; 
	} 
 
 
	trace("Client:         Get interface IUnknown from IY.") ; 
 
	IUnknown* pIUnknownFromIY = NULL ; 
	hr = pIY->QueryInterface(IID_IUnknown, (void**)&pIUnknownFromIY) ; 
	if (SUCCEEDED(hr)) 
	{ 
		cout << "Are the IUnknown pointers equal?  " ; 
		if (pIUnknownFromIY == pIUnknown) 
		{ 
			cout << "Yes, pIUnknownFromIY == pIUnknown." << endl ; 
		} 
		else 
		{ 
			cout << "No, pIUnknownFromIY != pIUnknown." << endl ; 
		} 
	} 
 
	// Delete the component. 
	delete pIUnknown ; 
 
	return 0 ; 
}