C++计时器

#pragma once
#include <windows.h> //头文件

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

class CHRTimer
{

private:
stopWatch timer;
LARGE_INTEGER frequency;
double LIToSecs( LARGE_INTEGER & L);
public:
CHRTimer();
void startTimer( );
void stopTimer( );
double getElapsedTime();
};

#include "StdAfx.h"
#include "HRTimer.h"

double CHRTimer::LIToSecs( LARGE_INTEGER & L)
{
return ((double)L.QuadPart /(double)frequency.QuadPart);
}

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

//开始计时
void CHRTimer::startTimer( )
{
QueryPerformanceCounter(&timer.start);
}

//停止计时
void CHRTimer::stopTimer( )
{
QueryPerformanceCounter(&timer.stop);
}

//获取运行时间
double CHRTimer::getElapsedTime() {
LARGE_INTEGER time;
time.QuadPart = timer.stop.QuadPart - timer.start.QuadPart;
return LIToSecs( time) ;
}

int sum=0;
CHRTimer timer;
timer.startTimer();//开始计时

for(int i=0;i<65665201;i++)
++sum;

timer.stopTimer();//停止计时

double time = timer.getElapsedTime(); //获取运行时间

cout<<"总共耗时："<<time<<endl;