std::chrono::time_zone::to_sys

C++

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Named requirements

Language support library

Concepts library (C++20)

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Utilities library

Strings library

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Numerics library

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Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

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Technical Specifications

Utilities library

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rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
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strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
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pair tuple (C++11) apply (C++17) make_from_tuple (C++17)	optional (C++17) any (C++17) variant (C++17)
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Date and time utilities

duration (C++11) time_point (C++11) time_of_day (C++20)	clock_time_conversion (C++20) clock_cast (C++20)
Clocks
system_clock (C++11) steady_clock (C++11) high_resolution_clock (C++11) is_clock (C++20)	utc_clock (C++20) tai_clock (C++20) gps_clock (C++20) file_clock (C++20) local_t (C++20)
Calendars
day (C++20) month (C++20) year (C++20) weekday (C++20) operator/ (C++20) year_month_day (C++20) year_month_day_last (C++20) year_month_weekday (C++20) year_month_weekday_last (C++20)	weekday_indexed (C++20) weekday_last (C++20) month_day (C++20) month_day_last (C++20) month_weekday (C++20) month_weekday_last (C++20) year_month (C++20)
Time zones
tzdb (C++20) tzdb_list (C++20) get_tzdbget_tzdb_listreload_tzdbremote_version (C++20)(C++20)(C++20)(C++20)	time_zone (C++20) locate_zone (C++20) current_zone (C++20) zoned_time (C++20) link (C++20) leap (C++20)
C-style date and time

std::chrono::time_zone

Member functions

time_zone::name

time_zone::get_info

time_zone::to_sys

time_zone::to_local

Nonmember functions

operator==operator!=operator<operator<=operator>operator>=

template< class Duration > auto to_sys(const std::chrono::local_time<Duration>& tp) const -> std::chrono::sys_time<std::common_type_t<Duration, std::chrono::seconds>>;		(since C++20)
template< class Duration > auto to_sys(const std::chrono::local_time<Duration>& tp, std::chrono::choose z) const -> std::chrono::sys_time<std::common_type_t<Duration, std::chrono::seconds>>;		(since C++20)

Converts the local_time tp in this time zone to the corresponding sys_time.

1) Throws an exception if the conversion is ambiguous or if tp represents a nonexistent time.

2) Resolves ambiguity according to the value of z:

• If z == std::chrono::choose::earliest, returns the earlier sys_time.
• If z == std::chrono::choose::latest, returns the later sys_time

If tp represents a nonexistent time between two UTC time_points, those two time_points will be the same, and that time_point will be returned.

Return value

The UTC equivalent of tp according to the rules of this time zone.

Exceptions

1) Throws a std::chrono::ambiguous_local_time if the conversion is ambiguous. Throws a std::chrono::nonexistent_local_time if tp represents a nonexistent time.

Notes

The precision of the result is at least std::chrono::seconds, and will be finer if the argument has finer precision.

Ambiguous and nonexistent local times can occur as a result of time zone transitions (such as daylight saving time). For example, "2016-03-13 02:30:00" does not exist in the "America/New_York" time zone, while "2016-11-06 01:30:00" in that time zone can correspond to two UTC time points: 2016-11-06 05:30:00 UTC and 2016-11-06 06:30:00 UTC.