C++ 时钟

#include <chrono>
//获取当前时间作为开始时间
std::chrono::high_resolution_clock::time_point m_startTime = std::chrono::high_resolution_clock::now(); 
 //获取当前时间作为结束时间
std::chrono::high_resolution_clock::time_point m_endTime = std::chrono::high_resolution_clock::now();
//开始到结束的时间间隔
//其中std::ratio<1,1000>代表时间单位，此处即1/1000s = ms,如果是<1,50>就是1/50s
std::chrono::duration<int, std::ratio<1,1000>> time_span_ms = std::chrono::duration_cast<std::duration<int,std::ratio<1,1000>>>(m_endTime - m_startTime);