sys_info struct

Provides a low-level interface to time zone information.

Syntax

struct sys_info;

Remarks

Provides a low-level interface to time zone information about the result of converting a sys_time to a local_time.

Members

Function	Description
abbrev	The abbreviation used for the associated time_zone and time_point.
begin, end	The range that the offset and abbrev apply to for the associated time zone.
offset	The Universal Time Coordinated (UTC) offset in effect for the associated time_zone and time_point.
save	Daylight savings time adjustment offset.

Non-members

Function	Description
operator<<	Output a sys_info to a stream.

abbrev

The abbreviation used for the associated time_zone and time_point.

string abbrev;

Return value

The abbreviation.

Remarks

Abbreviations aren't unique among the time_zones. This means you can't reliably map abbreviations back to a time_zone and UTC offset.

begin, end

Provides the range over the associated time zone, [begin, end), that the offset and abbrev apply to.

sys_seconds begin;
sys_seconds end;

Return value

The returned sys_seconds are offsets relative to the associated time_point.

offset

The UTC offset in effect for the associated time zone and time_point.

seconds offset;

Return value

The relationship between local_time and sys_time is: offset = local_time - sys_time.

save

Indicates whether the sys_info is on daylight savings time, and if so, suggests the offset this time zone might use if it weren't on daylight savings time.

minutes save;

Return value

If save != 0min, the time zone is on daylight saving time at the associated time_point. In that case, offset-save suggests what offset this time_zone might use if it not on daylight saving time.

This offset isn't authoritative. To get an authoritative offset, compare with a query against time zone using a time_point that doesn't fall during daylight savings time. That is, compare against a time_point that results in a save value of zero.

Example: get a sys_info

// compile using: /std:c++latest
#include <iostream>
#include <chrono>

using namespace std::chrono;

int main()
{
    sys_time<system_clock::duration> st = system_clock::now();
    
    const auto& timeZoneDatabase = get_tzdb();
    const auto& currentZone = timeZoneDatabase.current_zone();
    auto sysInfo = currentZone->get_info(st);

    std::cout << sysInfo << "\n";

    return 0;
}

begin: 2021-03-14 10:00:00, end: 2021-11-07 09:00:00, offset: -25200s, save: 60min, abbrev: PDT

Requirements

Header: <chrono>

Namespace: std::chrono

Compiler Option: /std:c++latest

<chrono>
file_clock class
high_resolution_clock
local_t struct
system_clock struct
tai_clock class
utc_clock class
Header Files Reference