Windows下C++计算代码段运行时间

LARGE_INTEGER BeginTime;    
LARGE_INTEGER EndTime;    
LARGE_INTEGER Frequency;    
QueryPerformanceFrequency(&Frequency);    
QueryPerformanceCounter(&BeginTime);

//要测试的代码放在这里   


QueryPerformanceCounter(&EndTime);   
//输出运行时间（单位：s）   
cout << "运行时间（单位：s）：" << (double)( EndTime.QuadPart - BeginTime.QuadPart ) / Frequency.QuadPart << endl;