std::chrono::zoned_time
Defined in header <chrono> |
||
|---|---|---|
template <
class Duration,
class TimeZonePtr = const std::chrono::time_zone*
> class zoned_time; |
(since C++20) | |
using zoned_seconds = std::chrono::zoned_time<std::chrono::seconds>; |
(since C++20) |
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.
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.
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.
Member types
| Member type | Definition |
|---|---|
duration |
std::common_type_t<Duration, std::chrono::seconds> |
Member functions
constructs a zoned_time (public member function) |
|
assigns value to a zoned_time (public member function) |
|
| obtains a copy of the time zone pointer (public member function) |
|
obtains the stored time point as a local_time (public member function) |
|
obtains the stored time point as a sys_time (public member function) |
|
| obtain information about the time zone at the stored time point (public member function) |
Non-member functions
|
(C++20)
|
compares two zoned_time values (function template) |
|
(C++20)
|
outputs a zoned_time into a stream (function template) |
Helper classes
|
(C++20)
|
specialization of std::formatter that formats a zoned_time according to the provided format (class template specialization) |
Deduction guides
Example
#include <chrono>
#include <iomanip>
#include <iostream>
#include <algorithm>
#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::chrono::nonexistent_local_time& ex) {
std::cout << "Error: " << ex.what() << '\n';
}
}
}
Possible output:
Africa/Casablanca - Zoned Time: 2021-09-16 10:26:54.837665555 +01
America/Argentina/Buenos_Aires - Zoned Time: 2021-09-16 06:26:55.090150136 -03
America/Barbados - Zoned Time: 2021-09-16 05:26:55.090419331 AST
America/Indiana/Petersburg - Zoned Time: 2021-09-16 05:26:55.090465623 EDT
Error: America/Tarasco_Bar not found in timezone database
Antarctica/Casey - Zoned Time: 2021-09-16 20:26:55.123070973 +11
Antarctica/Vostok - Zoned Time: 2021-09-16 15:26:55.123151218 +06
Asia/Magadan - Zoned Time: 2021-09-16 20:26:55.123208852 +11
Asia/Manila - Zoned Time: 2021-09-16 17:26:55.123434512 PST
Asia/Shanghai - Zoned Time: 2021-09-16 17:26:55.123520538 CST
Asia/Tokyo - Zoned Time: 2021-09-16 18:26:55.123626199 JST
Atlantic/Bermuda - Zoned Time: 2021-09-16 06:26:55.123713854 ADT
Australia/Darwin - Zoned Time: 2021-09-16 18:56:55.155857464 ACST
Europe/Isle_of_Man - Zoned Time: 2021-09-16 10:26:55.155909304 BST
Error: Europe/Laputa not found in timezone database
Indian/Christmas - Zoned Time: 2021-09-16 16:26:55.215065303 +07
Indian/Cocos - Zoned Time: 2021-09-16 15:56:55.215137548 +0630
Pacific/Galapagos - Zoned Time: 2021-09-16 03:26:55.215201447 -06
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