#include <chrono>
#include <iomanip>
#include <iostream>
#include <string>
#include <cerrno>
#include <cstdlib>
#include <cstring>
#include <ctime>

namespace chr = std::chrono;

void error(const std::string& function)
{
    if (errno)
    {
        std::string error_str = std::strerror(errno);
        std::cerr << function << "(): " << error_str << "\n";
    }
    else
        std::cerr << "Error: " << function << "()\n";
    std::exit(EXIT_FAILURE);
}

int main()
{
    auto tp = chr::system_clock::now();
    std::time_t t = chr::system_clock::to_time_t(tp);

    std::tm* p = std::gmtime(&t);
    if (!p)
        error("std::gmtime");
    std::tm utc = *p;

    p = std::localtime(&t);
    if (!p)
        error("localtime");
    std::tm local = *p;

    std::cout << std::put_time(&utc, "UTC: %F %T\n");
    std::cout << std::put_time(&local, "Local (UTC%z): %F %T\n");
}