Modern Chrono TimeZoneInfo LocalOffsetAt

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TimeZoneInfo.LocalOffsetAt

Returns the local zone's UTC offset in minutes at a given moment, DST included.

Syntax

TimeZoneInfo.LocalOffsetAt( byref i as Instant ) as int16

Notes

• The offset at that instant, not right now. Converting a July timestamp with January's offset is the commonest time-zone bug there is, and this is the call that avoids it.
• Minutes east of UTC: a zone behind UTC gives a negative number.
• An Invalid instant gives 0.
• Only the machine's own zone is available: there are no named zones and no time-zone database.

Examples

#import "std/chrono"
using chrono

dim as Instant jan = DateTime( 2026, 1, 15, 12, 0, 0, 0 ).AssumeUtc( )
dim as Instant jul = DateTime( 2026, 7, 15, 12, 0, 0, 0 ).AssumeUtc( )

'' Differ by the daylight-saving shift, where the zone has one
print TimeZoneInfo.LocalOffsetAt( jan ), TimeZoneInfo.LocalOffsetAt( jul )

print TimeZoneInfo.LocalOffsetAt( Instant.Invalid( ) )   '' 0

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Library: Chrono Date and Time
Category: Date and Time (Chrono)
Documented under: The Members