c++实现精确计时

//获取比较准确是程序运行时间

#include<iostream>

#include<windows.h>

using namespace std;

int main(void)

{

system("color F0");

cout.setf(ios::fixed);

cout.setf(ios::showpoint);

cout.precision(10);

//获取时钟频率

LARGE_INTEGER m_liPerfFreq={0};

QueryPerformanceFrequency(&m_liPerfFreq);

//获取初始计数

LARGE_INTEGER m_liPerfStart={0};

QueryPerformanceCounter(&m_liPerfStart);

//测试代码的位置

for(int ix=0;ix<100000;ix++){

cout<<" ";

}

//获取最后计数

LARGE_INTEGER liPerfNow={0};

QueryPerformanceCounter(&liPerfNow);

//计算时间

long long time=( ((liPerfNow.QuadPart - m_liPerfStart.QuadPart) * 1000)/m_liPerfFreq.QuadPart);

cout<<time<<endl;

system("pause");

return 0;

}