#include <sys/time.h> #include <iostream> #include <time.h> double get_wall_time() {   struct timeval time ;   if (gettimeofday(&time,NULL)){     return 0;   }   return (double)time.tv_sec + (double)time.tv_usec * .000001; }  int main() {   unsigned int t = 0;   double start_time = get_wall_time()   while(t++<10e+6);   double end_time = get_wall_time()   std::cout<<"循環耗時為:"<<end_time-start_time<<"ms";   return 0; } 

#include <windows.h> #include <iostream>  int main() {   DWORD start, stop;   unsigned int t = 0;   start = GetTickCount();   while (t++ < 10e+6);   stop = GetTickCount();   printf("time: %lld ms/n", stop - start);   return 0; }