代码优化试验——短循环优化（上）[6]

              j += i++;

              j += i++;

              j += i++;

              j += i++;

       }

}

int main()

{

      timer timer; double t;

       for (unsigned k = 0; k < 3; k++)

       {

              timer.start();

              sum1();

              t = timer.gettime();

              cout <<"sum1: " << t << endl;

              timer.start();

              sum2();

              t = timer.gettime();

              cout <<"sum2: " << t << endl;

              timer.start();

              sum3();

              t = timer.gettime();