การใช้ high Resolution Timer ด้วย c++

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

typedef struct {
	LARGE_INTEGER start;
	LARGE_INTEGER stop;
} stopWatch;

class CStopWatch {

private:
	stopWatch timer;
	LARGE_INTEGER frequency;
	double LIToSecs( LARGE_INTEGER & L) ;
public:
	CStopWatch() ;
	void startTimer( ) ;
	void stopTimer( ) ;
	double getElapsedTime() ;
};
double CStopWatch::LIToSecs( LARGE_INTEGER & L) {
	return ((double)L.QuadPart /(double)frequency.QuadPart) ;
}

CStopWatch::CStopWatch(){
	timer.start.QuadPart=0;
	timer.stop.QuadPart=0; 
	QueryPerformanceFrequency( &frequency ) ;
}

void CStopWatch::startTimer( ) {
	QueryPerformanceCounter(&timer.start) ;
}

void CStopWatch::stopTimer( ) {
	QueryPerformanceCounter(&timer.stop) ;
}

double CStopWatch::getElapsedTime() {
	LARGE_INTEGER time;
	time.QuadPart = timer.stop.QuadPart - timer.start.QuadPart;
	return LIToSecs( time) ;
}

#define n 200000

int main(int argc, char*argv[])
{
	int x[n];
	int j= 0;
	int k = 1;
	int l = 0;
	int m=0;
	CStopWatch timer;
	for(int k=1;k<n/2;k=k*2)
	{
		timer.startTimer();
		for(int l=0;l<20;l++)
		{
			
			for(int i=0;i< k;i++)
			{
				m=i;
				while(m<n)
				{
					//printf("%d ",m);
					x[m] = 7*x[m]*x[m];
					m = (m + k  )   ; 
				}
			}
		}
		timer.stopTimer();
		printf("\nk= %d -->  \t%lf\n\n",k,timer.getElapsedTime());
	}
	


}

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