C++ 函数性能分析：内存管理对性能的影响

#include <vector>

// 使用 std::vector 的案例
void vector_test() {
  std::vector<int> v(1000000);
  for (int i = 0; i < 1000000; i++) {
    v[i] = i;
  }
}

// 使用原始数组的案例
void array_test() {
  int* arr = new int[1000000];
  for (int i = 0; i < 1000000; i++) {
    arr[i] = i;
  }
  delete[] arr;
}

int main() {
  // 测量 vector_test 的执行时间
  auto t1 = std::chrono::high_resolution_clock::now();
  vector_test();
  auto t2 = std::chrono::high_resolution_clock::now();
  auto vector_time = std::chrono::duration_cast<std::chrono::milliseconds>(t2 - t1).count();

  // 测量 array_test 的执行时间
  t1 = std::chrono::high_resolution_clock::now();
  array_test();
  t2 = std::chrono::high_resolution_clock::now();
  auto array_time = std::chrono::duration_cast<std::chrono::milliseconds>(t2 - t1).count();

  std::cout << "Vector test time: " << vector_time << " ms" << std::endl;
  std::cout << "Array test time: " << array_time << " ms" << std::endl;

  return 0;
}