Relatively accurate counting of cycles per second (Frames Per Second). Suitable for variable FPS in applications and especially in games.

#include <windows.h>
#include <map>
#include <queue>

ULONGLONG resolution = 1000000, lastTime = 0, frequency = 1;
double lowId = 1;
std::queue<double> usedIds;
std::map<double, ULONGLONG> markers;

/*INIT*/
double Init()
{
	if (QueryPerformanceFrequency((LARGE_INTEGER *)&frequency) && QueryPerformanceCounter((LARGE_INTEGER*)&lastTime)) {
		return 0.0;
	}
	else {
		return -1.0;
	}
}

/*FPS*/
double FPS()
{
	ULONGLONG now, lt;
	if (QueryPerformanceCounter((LARGE_INTEGER*)&now)) {
		lt = lastTime;
		lastTime = now;
		return (double)1000000/((now - lt)*resolution/frequency);
	}
	else {
		return -1.0;
	}
}

int main(int argc, char* argv[])
{
	Init();
	while(1)
	{
		printf(">%f<\n", (float)FPS() );
		Sleep(12);
	}
	return 0;
}