std::chrono::zoned_time(3)

💖 std::chrono::zoned_time(3) 💖

okay bestie, this page comes from the C++ Standard Libary manual (yep, that's the spelling — we're keeping it). we're doing std::chrono::zoned_time, and it's lowkey iconic: time zone + time point, paired up. 🫶

🌸 NAME 🌸

std::chrono::zoned_time — std::chrono::zoned_time

✨ Synopsis ✨

Defined in header <chrono>

template<
    class Duration,
    class TimeZonePtr = const std::chrono::time_zone*
> class zoned_time;
using zoned_seconds = std::chrono::zoned_time<std::chrono::seconds>;

The template is (since C++20), and zoned_seconds is also (since C++20). periodt.

The class zoned_time represents a logical pairing of a time zone and a std::chrono::time_point whose resolution is Duration. 💫

An invariant of zoned_time is that it always refers to a valid time zone and represents an existing and unambiguous time point in that time zone. Consistent with this invariant, zoned_time has no move constructor or move assignment operator; attempts to move a zoned_time will perform a copy. so if you try to move it, it just copies — no cap. 😭

🚨 ill-formed alert: the program is ill-formed if Duration is not a specialization of std::chrono::duration.

The template parameter TimeZonePtr allows users to supply their own time zone pointer types and further customize the behavior of zoned_time via std::chrono::zoned_traits. Custom time zone types need not support all the operations supported by std::chrono::time_zone, only those used by the functions actually called on the zoned_time. iykyk ✨

TimeZonePtr must be MoveConstructible. Move-only TimeZonePtrs are allowed but difficult to use, as the zoned_time will be immovable and it is not possible to access the stored TimeZonePtr. bestie, read that again: immovable and you can't even reach the stored pointer. it's giving locked box energy. 🔒

💅 Member types 💅

• duration — std::common_type_t<Duration, std::chrono::seconds>

🎀 Member functions 🎀

• constructor — constructs a zoned_time (public member function)
• operator= — assigns value to a zoned_time (public member function)
• get_time_zone — obtains a copy of the time zone pointer (public member function)
• operator local_time, get_local_time — obtains the stored time point as a local_time (public member function)
• operator sys_time, get_sys_time — obtains the stored time point as a sys_time (public member function)
• get_info — obtain information about the time zone at the stored time point (public member function)

🦋 Non-member functions 🦋

• operator== — compares two zoned_time values (C++20) (function template)
• operator<< — outputs a zoned_time into a stream (C++20) (function template)

🌈 Helper classes 🌈

• std::formatter<std::chrono::zoned_time> — formatting support for zoned_time (C++20) (class template specialization)
• std::hash<std::chrono::zoned_time> — hash support for std::chrono::zoned_time (C++26) (class template specialization)

🧚 Deduction guides 🧚

the original page just drops this heading here with no extra text, so we're keeping it that way, bestie. 💫

🔥 Example 🔥

// Run this code

#include <algorithm>
#include <chrono>
#include <iomanip>
#include <iostream>
#include <stdexcept>
#include <string_view>

int main()
{
    constexpr std::string_view locations[] =
    {
        "Africa/Casablanca",   "America/Argentina/Buenos_Aires",
        "America/Barbados",    "America/Indiana/Petersburg",
        "America/Tarasco_Bar", "Antarctica/Casey",
        "Antarctica/Vostok",   "Asia/Magadan",
        "Asia/Manila",         "Asia/Shanghai",
        "Asia/Tokyo",          "Atlantic/Bermuda",
        "Australia/Darwin",    "Europe/Isle_of_Man",
        "Europe/Laputa",       "Indian/Christmas",
        "Indian/Cocos",        "Pacific/Galapagos",
    };

    constexpr auto width = std::ranges::max_element(locations, {},
        [](const auto& s){ return s.length(); })->length();

    for (const auto location : locations)
        try
        {
            // may throw if 'location' is not in the time zone database
            const std::chrono::zoned_time zt{location, std::chrono::system_clock::now()};
            std::cout << std::setw(width) << location << " - Zoned Time: " << zt << '\n';
        }
        catch (std::runtime_error& ex)
        {
            std::cout << "Error: " << ex.what() << '\n';
        }
}

🌟 Possible output 🌟

                     Africa/Casablanca - Zoned Time: 2023-06-29
       20:58:34.697449319 +01
        America/Argentina/Buenos_Aires - Zoned Time: 2023-06-29
       16:58:34.709957354 -03
                      America/Barbados - Zoned Time: 2023-06-29
       15:58:34.709977888 AST
            America/Indiana/Petersburg - Zoned Time: 2023-06-29
       15:58:34.709998072 EDT
        Error: tzdb: cannot locate zone: America/Tarasco_Bar
                      Antarctica/Casey - Zoned Time: 2023-06-30
       06:58:34.710093685 +11
                     Antarctica/Vostok - Zoned Time: 2023-06-30
       01:58:34.710107932 +06
                          Asia/Magadan - Zoned Time: 2023-06-30
       06:58:34.710121831 +11
                           Asia/Manila - Zoned Time: 2023-06-30
       03:58:34.710134751 PST
                         Asia/Shanghai - Zoned Time: 2023-06-30
       03:58:34.710153259 CST
                            Asia/Tokyo - Zoned Time: 2023-06-30
       04:58:34.710172815 JST
                      Atlantic/Bermuda - Zoned Time: 2023-06-29
       16:58:34.710191043 ADT
                      Australia/Darwin - Zoned Time: 2023-06-30
       05:28:34.710236720 ACST
                    Europe/Isle_of_Man - Zoned Time: 2023-06-29
       20:58:34.710256834 BST
        Error: tzdb: cannot locate zone: Europe/Laputa
                      Indian/Christmas - Zoned Time: 2023-06-30
       02:58:34.710360409 +07
                          Indian/Cocos - Zoned Time: 2023-06-30
       02:28:34.710377520 +0630
                     Pacific/Galapagos - Zoned Time: 2023-06-29
       13:58:34.710389952 -06

👑 See also 👑

• time_zone — represents a time zone (C++20) (class)

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💖 that's the whole page, bestie. source: http://cppreference.com, version/date: 2024.06.10, and the page is std::chrono::zoned_time(3). bye, go make time zones cute 💖