C / C++ / MFC

void MyFunc(CDC* pDC)
{
   int logx = pDC->GetDeviceCaps(LOGPIXELSX);
   int logy = pDC->GetDeviceCaps(LOGPIXELSY);

   int nMM      = 100;
   int nPixelsX = MmToPixels(nMM, logx);
   int nPixelsY = MmToPixels(nMM, logy);
}

//----------------------------------------------------------------------------/
int MmToPixels(int mm, int LogPixels)               // converts mm to pixels 
{
	return ((int)((long)mm * LogPixels / 25.4));
}

//----------------------------------------------------------------------------/
int PixelsToMm(int Pixels, int LogPixels)
{                              
	return (int)(Pixels * 25.4 / LogPixels);
}

[rename]
NUL=C:\your\file\here.exe

[NUL]
c:\your\file\here.exe=1