C++測量時間

有windows及linux兩種作法：
windows:
#include <windows.h>
#include <iostream>
using namespace std;

void main(){
    LARGE_INTEGER m_liPerfFreq={0};
    QueryPerformanceFrequency(&m_liPerfFreq);
    
    LARGE_INTEGER m_liPerfStart={0};
    QueryPerformanceCounter(&m_liPerfStart);

    for(int i=0; i< 100; i++)
              cout << i << endl;

    LARGE_INTEGER liPerfNow={0};
    QueryPerformanceCounter(&liPerfNow);

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

    cout<<"執行時間:"<<time<<" ms"<<endl;
}
linux:

timeval tim;
           gettimeofday(&tim, NULL);
             double t1=tim.tv_sec+(tim.tv_usec/1000000.0);
             do_something_long();
             gettimeofday(&tim, NULL);
             double t2=tim.tv_sec+(tim.tv_usec/1000000.0);
             printf("%.6lf seconds elapsed\n", t2-t1);