Timing Methods and Functions

#include <windows.h>
#include <stdio.h>

void main(void)
{
   long x, y;
   LARGE_INTEGER PerfFreq;
   LARGE_INTEGER PerfCountStart, PerfCountEnd, PerfDiff;
   float interval;

   QueryPerformanceFrequency(&PerfFreq);

   if (PerfFreq.QuadPart == 0)
   {
      printf("Your hardware doesn''t support High Resolution Perfomance Counters!\n");
      return;
   }

   PerfFreq.QuadPart = PerfFreq.QuadPart / 1000;  // ticks per millisecond

   QueryPerformanceCounter(&PerfCountStart);

   y = 0;
   for (x=0; x < 1000000L; x++)
      y = y + x;

   QueryPerformanceCounter(&PerfCountEnd);

   PerfDiff.QuadPart = PerfCountEnd.QuadPart - PerfCountStart.QuadPart;

   interval = (float)PerfDiff.QuadPart / (float)PerfFreq.QuadPart;

   printf("The loop took %7.4f milliseconds\n", interval);
}