C / C++ / MFC

#include <boost\logic\tribool.hpp>

using namespace boost;
using namespace std;

tribool test1();
tribool test2();

int _tmain(int argc, _TCHAR* argv[])
{
	if( !test1() || !test2() )
		cout << "test failed" << endl;
	
	return 0;
}

tribool test1()
{
	cout << "test1" << endl;
	return true;
}

tribool test2()
{
	cout << "test2" << endl;
	return false;
}

The operands of logical-AND and logical-OR expressions are evaluated from left to right. If the value of the first operand is sufficient to determine the result of the operation, the second operand is not evaluated. This is called "short-circuit evaluation." There is a sequence point after the first operand. See Sequence Points for more information. 

if( !static_cast<bool>(test1()) || !static_cast<bool>(test2()) )

void Fun(std::wstring)
{
/*
Function body
*/
}

LIBRARY Standby
EXPORTS
Fun

LoadLibary

C

int

char

int*

//these are declare in header(.h) file
        IPreviewHandler			*pHandle;
	IInitializeWithFile		*m_IFile;
	IInitializeWithStream	*m_IStream;
	IStream					*pStream;

/**********************************************************************/
//and before every preview i clear or release the previous handlers
//--------
//---------------------------------
	if(pHandle != NULL)
	{
		if(m_IFile!=NULL)
		{
			m_IFile->Release();
			m_IFile = NULL;
		}

		if(m_IStream!=NULL)
		{
			m_IStream->Release();
			m_IStream = NULL;
		}

		if(m_pStream != NULL)
		{
			m_pStream->Release();
			m_pStream = NULL;
		}

		pHandle->Unload();

		pHandle->Release();

		pHandle = NULL;

		CoUninitialize();
	}
	//---------------------------------
//--------
	HRESULT hres;
	WCHAR *pwcExtn = NULL;
	CString csClsid;	

	pwcExtn = StrRChr(szFile, NULL, L'.');
	csClsid = GetClsidFromExtn( pwcExtn );
	
	CLSID cls;

	pHandle = NULL;
	m_IFile = NULL;
	m_IStream = NULL;
	pStream   = NULL;
	

	if(CLSIDFromString( (LPWSTR)(LPCTSTR)csClsid,&cls) != NOERROR )
	{
		return 0;
	}
	else
	{
		CoInitialize(NULL);			

		hres = CoCreateInstance(
			cls,
			0,
			CLSCTX_INPROC_SERVER | CLSCTX_LOCAL_SERVER,
			IID_IPreviewHandler,(LPVOID*)&pHandle);

	 
		if (FAILED(hres))
		{
			CoUninitialize();
			return 0;                
		}
				

		hres = pHandle->QueryInterface(IID_IInitializeWithFile,(LPVOID*)&m_IFile );

		if (FAILED(hres))
		{	
                			hres = pHandle->QueryInterface(IID_IInitializeWithStream,(LPVOID*)&m_IStream );

			if (FAILED(hres))
			{
				
				CoUninitialize();
				return 0;                 
			}

			if(CreateStreamOnHGlobal(NULL, TRUE, &pStream) == S_OK)
			{
				CFileException pError ;
				CFile picFile;
				if(picFile.Open(szFile, CFile::modeRead | CFile::typeBinary,&pError))
				{
					BYTE pBuffer[1024];
					UINT uiRead = 0;

					while((uiRead = picFile.Read(pBuffer, sizeof(pBuffer))) != 0)
					{
						ULONG ulWritten = 0;
						pStream->Write(pBuffer, uiRead, &ulWritten);
					}

					picFile.Close();
				}
				else
				{
					
					TCHAR szError[1024];
					pError.GetErrorMessage(szError, 1024);
					AfxMessageBox(szError);
					
				}
				
			}
			
			m_IStream->Initialize(pStream,STGM_READ);
		}
		else
			hres = m_IFile->Initialize(szFile,STGM_READ);

		hres = pHandle->SetWindow( hWnd , &rectPreview );
		
		pHandle->DoPreview();
		
		pHandle->SetRect(&rectPreview);
				
	}	

std::list<std::basic_string<TCHAR>

string_list  szFile = (string_list) ppsp->lParam;