c/c++ program time-consuming

timer.cc

#include <chrono>
#include <iostream>

class Timer {
 public:
  Timer() : start_(std::chrono::high_resolution_clock::now()){};
  ~Timer() {
    auto end = std::chrono::high_resolution_clock::now();

    auto s = std::chrono::time_point_cast<std::chrono::microseconds>(start_)
                 .time_since_epoch()
                 .count();
    auto e = std::chrono::time_point_cast<std::chrono::microseconds>(end)
                 .time_since_epoch()
                 .count();

    auto dura = e - s;
    std::cout << "Duration: " << dura << "us(" << dura * 0.001 << " ms)\n";
  }

 private:
  std::chrono::time_point<std::chrono::high_resolution_clock> start_;
};

int main() {
  Timer timer;

  int res = 0;
  for (int i = 0; i < 10000; ++i) {
    res += i * 2;
  }
  return res;
}