SETTIMEZONE string-expression

Sets the system time zone to the value provided by string-expression.
The string must be a valid IANA time zone (tzdb) name, for example:

"Europe/London"
"America/New_York"
"Asia/Tokyo"

After setting the time zone, functions that are DST-aware will use it when you pass TRUE to them, such as:

TIME$(TRUE)
DATE$(TRUE)
HOUR(TRUE), MINUTE(TRUE), SECOND(TRUE)
DAY(TRUE), MONTH(TRUE), YEAR(TRUE)

When called with TRUE, these functions apply the selected time zone and any daylight saving time rules in effect for the timestamp they produce.

Note: The identifier must be an IANA tzdb name (e.g. "Europe/London").; Do not use Windows-style names like "GMT Standard Time" or abbreviations like "BST" or "PST".; Calling the date and time functions without the TRUE argument returns values without applying the configured time zone and DST adjustment.; If you are unsure of the exact spelling, consult the IANA tz database list and copy the region/city form verbatim, e.g. "America/Los_Angeles".

Examples

Set to the UK and print local date and time

SETTIMEZONE "Europe/London"
 
PRINT "Local date: "; DATE$(TRUE)
PRINT "Local time: "; TIME$(TRUE)
PRINT "Hour: "; HOUR(TRUE); "  Minute: "; MINUTE(TRUE); "  Second: "; SECOND(TRUE)

Compare adjusted versus unadjusted outputs

SETTIMEZONE "America/New_York"
 
PRINT "Unadjusted time: "; TIME$()
PRINT "Adjusted time:   "; TIME$(TRUE)

Switch to Tokyo and read parts

SETTIMEZONE "Asia/Tokyo"
 
PRINT "Y/M/D: "; YEAR(TRUE); "/"; MONTH(TRUE); "/"; DAY(TRUE)

Handle an invalid time zone

ON ERROR PROCbadtz
SETTIMEZONE "Not/AZone"
PRINT "This line is not reached if the name is invalid"
END
 
DEF PROCbadtz
    PRINT "Failed to set time zone: "; ERR$
ENDPROC

Behaviour

The setting affects the DST-aware forms of the listed functions when you pass TRUE.
The argument to SETTIMEZONE is a string expression and must resolve to a valid tzdb identifier.
An invalid identifier raises a runtime error (catch with ON ERROR PROC... if needed).

See also:
TIME$ · DATE$ · HOUR · MINUTE · SECOND · DAY · MONTH · YEAR