检测代码运行时间（微秒级）

#include <fstream>
using namespace std;

 

LARGE_INTEGER litmp;
 LONGLONG QPart1,QPart2;
 double dfMinus, dfFreq, dfTim;
 QueryPerformanceFrequency(&litmp);
 dfFreq = (double)litmp.QuadPart; // 获得计数器的时钟频率

 

ofstream fg;
    CString file = "d:\\17.txt";
    fg.open(file,ios::app);
    QueryPerformanceCounter(&litmp);
    QPart1 = litmp.QuadPart;             // 获得初始值

 

QueryPerformanceCounter(&litmp);
    QPart2 = litmp.QuadPart;   //获得中止值
    dfMinus = (double)(QPart2-QPart1);

    dfTim = dfMinus / dfFreq;    // 获得对应的时间值，单位为秒

    dfTim = dfMinus / dfFreq * 1000;    // 获得对应的时间值，单位为毫秒
    dfTim = dfMinus / dfFreq * 1000 * 1000;    // 获得对应的时间值，单位为微秒
    fg<<dfTim<<endl;
    fg.close();