Stringify chrono::time_point

stringify-chrono.cpp

#include <iostream>

#include <ctime>  // localtime, time_t, mktime, tm
#include <chrono>
#include <iomanip>  // put_time


using namespace std::chrono_literals;

int main()
{
    std::chrono::milliseconds x{1s};
    
    std::cout << x.count() << '\n'; 
    
    
    // 1918/11/18 00:00:01
    std::tm t;
    t.tm_sec = 1;
    t.tm_min = 0;
    t.tm_hour = 0;
    t.tm_hour = 0;
    t.tm_mday = 18;
    t.tm_mon = 10;
    t.tm_year = 18;
    t.tm_wday = 1;
    t.tm_yday = 322;
    t.tm_isdst = 1;
    
    auto y = std::chrono::system_clock::from_time_t(std::mktime(&t));
    auto z = std::chrono::system_clock::to_time_t(y);
    
    // ISO 8601
    std::time_t tt = std::mktime(&t);
    std::cout << std::put_time(std::localtime(&tt), "%FT%T%z" ) << '\n';
    std::cout << std::put_time(std::localtime(&z), "%FT%T%z" ) << '\n';
    
    return 0;
}

/*
http://coliru.stacked-crooked.com/a/b481641ae46a803c

1000
1918-11-18T00:00:01+0000
1918-11-18T00:00:01+0000
*/