计算时间差

1、chrono：参考链接

auto start = std::chrono::high_resolution_clock::now();
someFunction();
auto end = std::chrono::high_resolution_clock::now();
auto duration = std::chrono::duration_cast<std::chrono::milliseconds>(end - start);
std::cout << "Function took " << duration.count() << " milliseconds to execute." << std::endl;