代码优化试验——短循环优化（上）[7]

              cout <<"sum3: " << t << endl;

              timer.start();

              sum4();

              t = timer.gettime();

              cout <<"sum4: " << t << endl;

              timer.start();

              sum5();

              t = timer.gettime();

              cout <<"sum5: " << t << endl;

              timer.start();

              sum6();

              t = timer.gettime();

              cout <<"sum6: " << t << endl;

              timer.start();

              sum7();

              t = timer.gettime();

              cout <<"sum7: " << t << endl;

              timer.start();

              sum8();