std::chrono::zoned_time<Duration,TimeZonePtr>:: zoned_time

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std::chrono::zoned_time
zoned_time ( ) ;
(1) (since C++20)
zoned_time ( const std:: chrono :: sys_time < Duration > & st ) ;
(2) (since C++20)
zoned_time ( const zoned_time & other ) = default ;
(3) (since C++20)
template < class Duration2 >
zoned_time ( const std:: chrono :: zoned_time < Duration2, TimeZonePtr > & other ) ;
(4) (since C++20)
explicit zoned_time ( TimeZonePtr z ) ;
(5) (since C++20)
explicit zoned_time ( std:: string_view name ) ;
(6) (since C++20)
zoned_time ( TimeZonePtr z, const std:: chrono :: sys_time < Duration > & st ) ;
(7) (since C++20)
zoned_time ( std:: string_view name, const std:: chrono :: sys_time < Duration > & st ) ;
(8) (since C++20)
zoned_time ( TimeZonePtr z, const std:: chrono :: local_time < Duration > & tp ) ;
(9) (since C++20)
zoned_time ( std:: string_view name, const std:: chrono :: local_time < Duration > & tp ) ;
(10) (since C++20)
zoned_time ( TimeZonePtr z, const std:: chrono :: local_time < Duration > & tp,
std:: chrono :: choose c ) ;
(11) (since C++20)
zoned_time ( std:: string_view name,
const std:: chrono :: local_time < Duration > & tp, std:: chrono :: choose c ) ;
(12) (since C++20)
template < class Duration2, class TimeZonePtr2 >

zoned_time ( TimeZonePtr z,

const std:: chrono :: zoned_time < Duration2, TimeZonePtr2 > & zt ) ;
(13) (since C++20)
template < class Duration2, class TimeZonePtr2 >

zoned_time ( TimeZonePtr z,
const std:: chrono :: zoned_time < Duration2, TimeZonePtr2 > & zt,

std:: chrono :: choose ) ;
(14) (since C++20)
template < class Duration2, class TimeZonePtr2 >

zoned_time ( std:: string_view name,

const std:: chrono :: zoned_time < Duration2, TimeZonePtr2 > & zt ) ;
(15) (since C++20)
template < class Duration2, class TimeZonePtr2 >

zoned_time ( std:: string_view name,
const std:: chrono :: zoned_time < Duration2, TimeZonePtr2 > & zt,

std:: chrono :: choose ) ;
(16) (since C++20)

Constructs a zoned_time object, initializing the stored time zone pointer and time point according to the following table, where traits is std:: chrono :: zoned_traits < TimeZonePtr > :

Overload Time zone pointer (denoted zone ) Time point (a std:: chrono :: sys_time < duration > ) Notes
(1) traits :: default_zone ( ) default constructed (a)
(2) st
(3) other. get_time_zone ( ) other. get_sys_time ( ) (b)
(4) other. get_time_zone ( ) other. get_sys_time ( ) (e)
(5) std :: move ( z ) default constructed
(6) traits :: locate_zone ( name ) (c)
(7) std :: move ( z ) st
(8) traits :: locate_zone ( name ) (c)
(9) std :: move ( z ) zone - > to_sys ( tp ) (d)
(10) traits :: locate_zone ( name ) (c,d)
(11) std :: move ( z ) zone - > to_sys ( tp, c ) (d)
(12) traits :: locate_zone ( name ) (c,d)
(13,14) std :: move ( z ) zt. get_sys_time ( ) (e)
(15,16) traits :: locate_zone ( name ) (c,e)
a) Constructors specified to call traits :: default_zone ( ) (1,2) do not participate in overload resolution if that expression is not well-formed.
b) The defaulted copy constructor (3) is defined as deleted if std:: is_copy_constructible_v < TimeZonePtr > is false.
c) Constructors with a std::string_view parameter name (6,8,10,12,15,16) do not participate in overload resolution if traits :: locate_zone ( name ) is not well-formed or if that expression is not convertible to TimeZonePtr .
d) Constructors specified to call zone - > to_sys (9-12) do not participate in overload resolution if that call expression is not well-formed or if the result is not convertible to std:: chrono :: sys_time < duration > .
e) Constructors with a template parameter Duration2 (4,13-16) do not participate in overload resolution if Duration2 is not convertible to Duration .

The behavior is undefined if the time zone pointer (initialized as described above) does not refer to a time zone.

Notes

zoned_time does not have a move constructor and attempting to move one will perform a copy instead using the defaulted copy constructor (3) . Thus, when TimeZonePtr is a move-only type, zoned_time is immovable: it can be neither moved nor copied.

The constructors (14,16) accept a std::chrono::choose parameter, but that parameter has no effect.

Example

Run this code 
#include <chrono>
#include <iostream>
#include <string_view>
 
int main()
{
    using std::chrono_literals::operator""y;
    using std::operator""sv;
 
    std::cout << std::chrono::zoned_time{} << " : default\n";
 
    constexpr std::string_view location1{"America/Phoenix"sv};
    std::cout << std::chrono::zoned_time{location1} << " : " << location1 << '\n';
 
    const std::chrono::time_zone* timeZonePtr = std::chrono::locate_zone("UTC");
    std::cout << std::chrono::zoned_time{timeZonePtr} << " : UTC time zone\n";
 
    constexpr auto location2{"Europe/Rome"sv};
    std::cout << std::chrono::zoned_time{location2, std::chrono::local_days{2021y/12/31}}
              << " : " << location2 << '\n';
 
    constexpr auto location3{"Europe/Rome"sv};
    constexpr auto some_date = std::chrono::sys_time<std::chrono::days>{2021y/12/31};
    std::cout << std::chrono::zoned_time{location3, some_date}
              << " : " << location3 << '\n';
 
    const auto now =
        std::chrono::floor<std::chrono::minutes>(std::chrono::system_clock::now());
    constexpr auto location4{"Europe/Rome"sv};
    std::cout << std::chrono::zoned_time{location4, now} << " : " << location4 << '\n';
 
    constexpr auto NewYork{"America/New_York"sv};
    constexpr auto Tokyo{"Asia/Tokyo"sv};
    const std::chrono::zoned_time tz_Tokyo{Tokyo, now};
    const std::chrono::zoned_time tz_NewYork{NewYork, now};
    std::cout << std::chrono::zoned_time{Tokyo, tz_NewYork} << " : " << Tokyo << '\n';
    std::cout << std::chrono::zoned_time{NewYork, tz_Tokyo} << " : " << NewYork << '\n';
}

Possible output: 

1970-01-01 00:00:00 UTC : default
1969-12-31 17:00:00 MST : America/Phoenix
1970-01-01 00:00:00 UTC : UTC time zone
2021-12-31 00:00:00 CET : Europe/Rome
2021-12-31 01:00:00 CET : Europe/Rome
2021-09-20 23:04:00 CEST : Europe/Rome
2021-09-21 06:04:00 JST : Asia/Tokyo
2021-09-20 17:04:00 EDT : America/New_York
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