C++中计算代码的执行时间

用高精度计时器
#include <iostream>
#include <windows.h>
using namespace std ;

int main(void)
{
 LARGE_INTEGER BegainTime ; 
 LARGE_INTEGER EndTime ; 
 LARGE_INTEGER Frequency ;
 QueryPerformanceFrequency(&Frequency);
 QueryPerformanceCounter(&BegainTime) ;
 //要测试的代码放在这里
 QueryPerformanceCounter(&EndTime) ;
 cout << ( EndTime.QuadPart - BegainTime.QuadPart )*1000 / Frequency.QuadPart ;

 system("pause") ;
 return 0 ;
}