C++ 计算运行时间间隔

C++11引入的新特性可以方便的计算程序运行的时间间隔，如下：

#include <chrono>
// C++11
auto startTime = std::chrono::high_resolution_clock::now();
/*
* your code
*/
auto stopTime = std::chrono::high_resolution_clock::now();
auto duration = std::chrono::duration_cast<std::chrono::microseconds>(stopTime - startTime);
std::cout << "Sec:" << duration.count() / 1000 << std::endl;