C / C++ / MFC

union tree_ctrl_item
{
    DWORD packed_;
    struct
    {
        DWORD bits_24_ : 24;
        DWORD bits_8_  : 8;
    }
    unpacked_;
};

void CGDICarSampleDlg::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
	// TODO: Add your message handler code here and/or call default
	if (nChar == 8) {
		myCar.Backward();
		// force a repaint of the canvass
		Invalidate();

	}
	else if (nChar == 32) {
		myCar.Forward();
		// force a repaint of the canvass
		Invalidate();

	}
	else if (nChar == 80){

		CColorDialog dlg;
		if (dlg.DoModal() == IDOK)
		{
			color = dlg.GetColor();
		} 
			red = GetRValue(color);
			green = GetGValue(color);
			blue = GetBValue(color);

			char rr[32]; 
			itoa(red, rr, 10); 
			r = rr; 

			char gg[32]; 
			itoa(green, gg, 10); 
			g = gg; 

			char bb[32]; 
			itoa(blue, bb, 10); 
			b = bb; 

			myCar.m_brCar.Detach();
			myCar.m_brCar.CreateSolidBrush(RGB(red, green, blue));

		WritePrivateProfileString("car", "red", r,		/*D:\lg.manuel\daily quests\GDICarSample\GDICarSample\*/"car.ini");
		WritePrivateProfileString("car", "green", g,	/*D:\lg.manuel\daily quests\GDICarSample\GDICarSample\*/"car.ini");
		WritePrivateProfileString("car", "blue", b,		/*D:\lg.manuel\daily quests\GDICarSample\GDICarSample\*/"car.ini");
	

		myCar.PickColor();
		//force a repaint of the canvass
		Invalidate();
	}
	else {
		TRACE( "others" );
	}

	CDialog::OnKeyDown(nChar, nRepCnt, nFlags);
}

void CCar::Forward()
{
	m_nCarX += 5;
	angleFlag = angleFlag + 1;

}

void CCar::Backward()
{
	m_nCarX -= 3;
	angleFlag = angleFlag - 1;
}

//button click handler
void CGDICarSampleDlg::OnBnClickedButtonColour()
{
	// colour picker code here
}

BOOL CGDICarSampleDlg::PreTranslateMessage(MSG* pMsg)
{
	// TODO: Add your specialized code here and/or call the base class

	if(WM_KEYDOWN == pMsg->message)
	{
		KeyDownHandler(pMsg->wParam);
		return TRUE;
	}

	return CDialog::PreTranslateMessage(pMsg);
}

void CGDICarSampleDlg::KeyDownHandler(UINT nChar)
{
	if (nChar == 8) 
	{		
		//move car backward
	}	
	else if (nChar == 32) 
	{			
		//move car backward		
	}

	//other cases..
}

BOOL CGDICarSampleDlg::PreTranslateMessage(MSG* pMsg)
{
	// TODO: Add your specialized code here and/or call the base class

	if(WM_KEYDOWN == pMsg->message)
	{
	OnKeyDown(pMsg->wParam);
	return TRUE;
	}

	return CDialog::PreTranslateMessage(pMsg);
}

error C2660: 'CGDICarSampleDlg::OnKeyDown' : function does not take 1 arguments

void CGDICarSampleDlg::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
	// TODO: Add your message handler code here and/or call default
	if (nChar == 8) {
		myCar.Backward();
		// force a repaint of the canvass
		Invalidate();

	}
	else if (nChar == 32) {
		myCar.Forward();
		// force a repaint of the canvass
		Invalidate();

	}
	else {
		TRACE( "others" );
	}

	CDialog::OnKeyDown(nChar, nRepCnt, nFlags);
}

afx_msg void OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags);

BOOL CGDICarSampleDlg::PreTranslateMessage(MSG* pMsg)
{
	if(WM_KEYDOWN == pMsg->message)
	{
	    //OnKeyDown(pMsg->wParam); //???
            KeyDownHandler(pMsg->wParam); //call my KeyDownHandler
            return TRUE;
	}

	return CDialog::PreTranslateMessage(pMsg);
}

//This is my KeyDownHandler, add this function to your class.
void CGDICarSampleDlg::KeyDownHandler(UINT nChar)
{
	if (nChar == 8) 
	{		
		//move car backward
	}	
	else if (nChar == 32) 
	{			
		//move car backward		
	}

	//other cases..
}

#if defined (_UNICODE) || defined (UNICODE)
#typedef basic_fstream<wchar_t,char_traits<wchar_t>> fstream 
#else 
#typedef basic_fstream<char, char_traits<char>> fstream  
#endif

typedef std::basic_fstream<TCHAR> file_stream;