C / C++ / MFC

#if defined(_UNICODE)
// in these cases the default (TCHAR) is the same as OLECHAR
	inline BSTR T2BSTR_EX(__in_opt LPCTSTR lp) {return ::SysAllocString(lp);}
	inline BSTR A2BSTR_EX(__in_opt LPCSTR lp) {return A2WBSTR(lp);}
	inline BSTR W2BSTR_EX(__in_opt LPCWSTR lp) {return ::SysAllocString(lp);}

#ifndef _ATL_EX_CONVERSION_MACROS_ONLY

	inline BSTR T2BSTR(__in_opt LPCTSTR lp) {return ::SysAllocString(lp);}
	inline BSTR A2BSTR(__in_opt LPCSTR lp) {return A2WBSTR(lp);}
	inline BSTR W2BSTR(__in_opt LPCWSTR lp) {return ::SysAllocString(lp);}
	
#endif	// _ATL_EX_CONVERSION_MACROS_ONLY

#else // !defined(_UNICODE)
	inline BSTR T2BSTR_EX(__in_opt LPCTSTR lp) {return A2WBSTR(lp);}
	inline BSTR A2BSTR_EX(__in_opt LPCSTR lp) {return A2WBSTR(lp);}
	inline BSTR W2BSTR_EX(__in_opt LPCWSTR lp) {return ::SysAllocString(lp);}
	
#ifndef _ATL_EX_CONVERSION_MACROS_ONLY

	inline BSTR T2BSTR(__in_opt LPCTSTR lp) {return A2WBSTR(lp);}
	inline BSTR A2BSTR(__in_opt LPCSTR lp) {return A2WBSTR(lp);}
	inline BSTR W2BSTR(__in_opt LPCWSTR lp) {return ::SysAllocString(lp);}

#endif	// _ATL_EX_CONVERSION_MACROS_ONLY

#endif // defined(_UNICODE)

// atlconv.h

_Check_return_ inline BSTR A2WBSTR(_In_opt_ LPCSTR lp, int nLen = -1)
{
	if (lp == NULL || nLen == 0)
		return NULL;
	USES_CONVERSION_EX;
	BSTR str = NULL;
#pragma warning(push)
#pragma warning(disable: 6385)
	int nConvertedLen = MultiByteToWideChar(_acp_ex, 0, lp,
		nLen, NULL, NULL);
#pragma warning(pop)
	int nAllocLen = nConvertedLen;
	if (nLen == -1)
		nAllocLen -= 1;  // Don't allocate terminating '\0'
	str = ::SysAllocStringLen(NULL, nAllocLen);

	if (str != NULL)
	{
		int nResult;
		nResult = MultiByteToWideChar(_acp_ex, 0, lp, nLen, str, nConvertedLen);
		ATLASSERT(nResult == nConvertedLen);
		if(nResult != nConvertedLen)
		{
			SysFreeString(str);
			return NULL;
		}

	}
	return str;
}

inline BSTR A2BSTR(_In_opt_ LPCSTR lp) {return A2WBSTR(lp);}

CPallini wrote:

A2BSTR do no more and no less then calling A2WBSTR, i.e. their effect is identical

Dave Calkins wrote:

Anyway, I'm just curious if anyone else has seen or used this. It caught me off guard.

new (value) Type

James R. Twine wrote:

I think that placement new is the only way to pass parameters to new...?

Cedric Moonen wrote:

AFAIK, you can override the new operator. I think that's what is done for the MFC

Mark Salsbery
Microsoft MVP - Visual C++

dharani wrote:

I call RegCreateKeyEx to create a key in the Vista registry , but it fails .

dharani wrote:

KEY_ALL_ACCESS