C / C++ / MFC

FILETIME current_time ;
FILETIME start ;

::GetSystemTimeAsFileTime(&start) ;
Sleep(100) ;
::GetSystemTimeAsFileTime(¤t_time) ;
double elapsed = CalculateElapsedTime(&start, & current_time) ;

double CalculateElapsedTime(FILETIME *start, FILETIME *current)
{
	double	elapsed_time ;
	__int64	st ;
	__int64	ct ;
	__int32	*p ;

	p = (__int32*)&st ;
	*p++ = start->dwLowDateTime ;
	*p = start->dwHighDateTime ;
	//st = (start->dwHighDateTime << 32) + start->dwLowDateTime ;
	p = (__int32*)&ct ;
	*p++ = current->dwLowDateTime ;
	*p = current->dwHighDateTime ;
	//ct = (current->dwHighDateTime << 32) + current->dwLowDateTime ;
	elapsed_time = (double)(ct - st) ;
	elapsed_time /= 10000000.0 ;	// convert from 100ns intervals to seconds
	return elapsed_time ;
}

void logAppName()
{
  static bool appAlreadyLogged=false;
  if(appAlreadyLogged) return;
  ...
  appAlreadyLogged=true;
}

void logAppName(const char* appName)
{
  static std::set<std::string> appsLogged;
  if(appsLogged.insert(appName).second==false)return;
  ...
}