時間點與時間段

// system_clock example
#include <iostream>
#include <ctime>
#include <ratio>
#include <>

using namespace std;
using namespace std::chrono;

int main()
{
    using std::chrono::system_clock;

    std::chrono::duration<int> one_day(1);

    system_clock::time_point today 
 
= system_clock::now();
    system_clock::time_point tomorrow = today + one_day;

    std::time_t tt;

    tt = system_clock::to_time_t(today);
    
    // duration<long long, nano> nanoseconds;   //納秒
    // duration<long long, micro> microseconds;   //微妙
    // duration<long long, milli> milliseconds;   
 
//毫秒
    // duration<long long> seconds;
    // duration<int, ratio<60> > minutes;
    // duration<int, ratio<3600> > hours;

    std::chrono::milliseconds ms = std::chrono::duration_cast<std::chrono::milliseconds>(tomorrow- today);
    //std::cout << "time is: " << ms.count() << "\n";
 

    std::cout << "time is: " <<today.time_since_epoch().count() << "\n"; //納秒
    std::cout << "time is: " << std::chrono::duration_cast<std::chrono::milliseconds>(today.time_since_epoch()).count() << "\n";  //毫秒

    //std::cout << "today is: " << ctime(&tt);
    std::cout << "today is: " << tt <<"\n";
    tt = system_clock::to_time_t(tomorrow);
    //std::cout << "tomorrow will be: " << ctime(&tt);
    std::cout << "tomorrow will be: " << tt<<"\n";
    return 0;
}