Getting a correct - not today - time from another timezone

Forum|Forum|5 years ago
August 20, 2020
16 replies
0 views

Ingo Stiller
Participating Frequently

Hi Freaks

Just a simple question 🙂
How to get the correct time from another timezone, if the day is not today?

Example:

I do have two timestamps, both created in germany

1) 2020101T180000 (1 january of 2020, 6 PM CET)
1) 2020501T180000 (1 may of 2020 , 6 PM CEST)

Now I want to convert them to UTC

The correct values would be:

1) 2020101T170000Z (1 january of 2020, 5 PM UTC)
1) 2020501T160000Z (1 may of 2020 , 4 PM UTC)

Problem is, that the difference is not a constant, but depends on "daylight saving"

With $nlstimezone set to UTC, I got only $datim as the currenct time in UTC

$nlstimezone
*Returned by the Proc functions $clock, $date, and $datim
*Displayed in fields with data types date, time, or combined date and time
*Stored and retrieved in the database
*Exchanged when using XML, call-in, or call-out

This does not include formating of datetime into a string, so
v_TIMESTAMP = "020101180000"
$nlstimezone="UTC"
$1 = "%%v_TIMESTAMP%%%"
does not give the correct value (as it doesn't convert at all)
As I want to convert a timestamp to the correct "Zulu" time with global procedures, I can't use field or database access

Any idea how to simple convert a timestamp to the correct time in another timezone?

Regards Ingo

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 20, 2020

Hi Freaks

Just a simple question 🙂
How to get the correct time from another timezone, if the day is not today?

Example:

I do have two timestamps, both created in germany

1) 2020101T180000 (1 january of 2020, 6 PM CET)
1) 2020501T180000 (1 may of 2020 , 6 PM CEST)

Now I want to convert them to UTC

The correct values would be:

1) 2020101T170000Z (1 january of 2020, 5 PM UTC)
1) 2020501T160000Z (1 may of 2020 , 4 PM UTC)

Problem is, that the difference is not a constant, but depends on "daylight saving"

With $nlstimezone set to UTC, I got only $datim as the currenct time in UTC

Any idea how to simple convert a timestamp to the correct time in another timezone?

Regards Ingo

Strange, Roger send me an answer via noreply@uniface.com, but I didn't see them here!?!?

Rogger suggest du use database fields and the write mit timezone="UTC"
For two reasons this will not work 🙂

1) I try to implement the conversion as an globale procedure

2) The data is already written, millions of rows. All date/time fields use the local time (i.e. CET/CEST)

My job is to use this data und create CRS(common reporting standard) XML-Files.
[or better to modify an old programm to the new CRS version]
And the (only german?) tax authority wants to see date/time in UTC ("Z")
When compiling the XML, I have to convert all fields accorging to CRS and XML standards
Using a general offset (say 1 hour UTC→CET) does not work, as some dates are written in winter (CET) in some in sommer (CEST) and UnifAce only use $nlstimezone for the current $datim and/or the whole XML (if using UnifAce XML-operations)

So, how to find the offset for a arbirtary date?

Ingo

Roger Wallin
Participating Frequently
Forum|Forum|5 years ago
August 20, 2020

Strange, Roger send me an answer via noreply@uniface.com, but I didn't see them here!?!?

Rogger suggest du use database fields and the write mit timezone="UTC"
For two reasons this will not work 🙂

1) I try to implement the conversion as an globale procedure

2) The data is already written, millions of rows. All date/time fields use the local time (i.e. CET/CEST)

So, how to find the offset for a arbirtary date?

Ingo

Hi Ingo,

yes I deleted it, as it went wrong in all kind of ways. First I didn't notice that you can't use the database, second my algorithm wasn't correct 😔.

My database solution is something like this:
actTimeZone = $nlstimezone
$nlstimezone = "UTC"
Store date into temporary database-table column
$nlstimezone = actTimeZone
retrieve date from temporary database-table column.

Otherwise I don't think that you can solve it just in Uniface, you probably have to use some kind of database-procedure or web-service....

Regards RogerW.

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 20, 2020

Hi Freaks

Just a simple question 🙂
How to get the correct time from another timezone, if the day is not today?

Example:

I do have two timestamps, both created in germany

1) 2020101T180000 (1 january of 2020, 6 PM CET)
1) 2020501T180000 (1 may of 2020 , 6 PM CEST)

Now I want to convert them to UTC

The correct values would be:

1) 2020101T170000Z (1 january of 2020, 5 PM UTC)
1) 2020501T160000Z (1 may of 2020 , 4 PM UTC)

Problem is, that the difference is not a constant, but depends on "daylight saving"

With $nlstimezone set to UTC, I got only $datim as the currenct time in UTC

Any idea how to simple convert a timestamp to the correct time in another timezone?

Regards Ingo

Hi Roger

Just trying to use $clock(<source>) with $nlstimezone

$nlsformat="classic"
$nlstimezone="classic"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="UTC"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="CET"
v_TIME = $clock("180000")

$nlsformat="classic"
$nlstimezone="classic"

the result is always the same "180000"
How does $clock work with $nlstimezone?

9.4.01

Additional option for overriding the default behavior if the time zone has been defined (using $nlstimezone or $NLS_TIME_ZONE)

Ingo

Roger Wallin
Participating Frequently
Forum|Forum|5 years ago
August 20, 2020

Hi Roger

Just trying to use $clock(<source>) with $nlstimezone

$nlsformat="classic"
$nlstimezone="classic"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="UTC"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="CET"
v_TIME = $clock("180000")

$nlsformat="classic"
$nlstimezone="classic"

the result is always the same "180000"
How does $clock work with $nlstimezone?

9.4.01

Additional option for overriding the default behavior if the time zone has been defined (using $nlstimezone or $NLS_TIME_ZONE)

Ingo

This works

$nlstimezone = "UTC"
testansv = "%%$clock%%%"

ie. at 17:08 it shows 14:08 in Finland.

apparently not working as you give some own <source>....

Regards Roger

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 20, 2020

Hi Roger

Just trying to use $clock(<source>) with $nlstimezone

$nlsformat="classic"
$nlstimezone="classic"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="UTC"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="CET"
v_TIME = $clock("180000")

$nlsformat="classic"
$nlstimezone="classic"

the result is always the same "180000"
How does $clock work with $nlstimezone?

9.4.01

Additional option for overriding the default behavior if the time zone has been defined (using $nlstimezone or $NLS_TIME_ZONE)

Ingo

Hi Roger

That's the same then $datim 🙂
But as UnifAce mention $clock,$date and $datime should "recognize" the timezone setting.
If this is only true without a source all of the functions are useless for converting a time, date, datetime 😔

: Any idea to convert a date from one timezone to another?

Ingo

DanielIseli
Rocketeer
Forum|Forum|5 years ago
August 21, 2020

Hi Roger

Just trying to use $clock(<source>) with $nlstimezone

$nlsformat="classic"
$nlstimezone="classic"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="UTC"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="CET"
v_TIME = $clock("180000")

$nlsformat="classic"
$nlstimezone="classic"

the result is always the same "180000"
How does $clock work with $nlstimezone?

9.4.01

Additional option for overriding the default behavior if the time zone has been defined (using $nlstimezone or $NLS_TIME_ZONE)

Ingo

Hi Ingo,

When you also use $nlsinternaltime = "UTC" then you should be able to do some time zone calculations.

$nlsinternaltime = "UTC"
$nlstimezone = "UTC"
putmess vTime
putmess "%%vTime%%%"
$nlstimezone = "CET"
putmess vTime
putmess "%%vTime%%%"
$nlsinternaltime = "classic"
$nlstimezone = "classic"

In case vTime is "01012020180000" (1-January-2020 18:00) then the external values (%%vTime%%%) are:

UTC: 1-January-2020 18:00
CET: 1-January-2020 19:00

And when vTime is "01052020180000" (1-May-2020 18:00) then the external values are:

UTC: 1-May-2020 18:00
CET: 1-May-2020 20:00

With this you should be able to reverse the values from CET to UTC.

If you would store the date values in the database from the start using $nlsinternaltime = "UTC" then this would be even easier, since in the database you then always have the UTC value and with $nlstimezone you then can display the value in the required time zone. In the case at hand you already have time zone dependent data in the database and that makes things a bit more complicated.

I hope this helps.

Daniel

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 21, 2020

Hi Roger

Just trying to use $clock(<source>) with $nlstimezone

$nlsformat="classic"
$nlstimezone="classic"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="UTC"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="CET"
v_TIME = $clock("180000")

$nlsformat="classic"
$nlstimezone="classic"

the result is always the same "180000"
How does $clock work with $nlstimezone?

9.4.01

Additional option for overriding the default behavior if the time zone has been defined (using $nlstimezone or $NLS_TIME_ZONE)

Ingo

Hi Daniel

So I build a function wich converts a datetime variable to text an UTC to another timezone:

ENTRY LF_CNV_UTC_TZ
  returns string
  params
    datetime v_DATIM :IN
    string   v_TZ    :IN
  endparams
  variables
    string  v_TXT
    string  v_TZ_R1,v_TZ_R2
  endvariables
  v_TZ_R1 = $nlsinternaltime
  v_TZ_R2 = $nlstimezone
  $nlsinternaltime = "UTC"
  $nlstimezone = v_TZ
  v_TXT = "%%v_DATIM%%%"
  $nlsinternaltime = v_TZ_R1
  $nlstimezone = v_TZ_R2
  $status = 0
  RETURN(v_TXT)
END

To draw backs:

1) The opposite conversion (TZ→UTC) does not work that simple

2) the result is a text, not datetime

To solve 1) I need the time difference in minutes
(Some countries do have an offset of n hours and 30 minutes ...)
But subtract on text from another doesn't work ...

So I have to solve 2)
This looks easy, but it isn't
Which datetime-formats uses the current UnifAce application?
The text could have anny format.
I will try to use a global variable with predefined format

When all this is working, it should possible to create a function
LF_CNH_TZ1_TO_TZ2

Isn't this a task for the programm language?

Ingo

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 21, 2020

Hi Roger

Just trying to use $clock(<source>) with $nlstimezone

$nlsformat="classic"
$nlstimezone="classic"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="UTC"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="CET"
v_TIME = $clock("180000")

$nlsformat="classic"
$nlstimezone="classic"

the result is always the same "180000"
How does $clock work with $nlstimezone?

9.4.01

Additional option for overriding the default behavior if the time zone has been defined (using $nlstimezone or $NLS_TIME_ZONE)

Ingo

So, I hope I got the (almost) final solution:

; convert datetime from timezone 1 to timezone 2
ENTRY LF_CNV_TZ1_TZ2
  returns datetime
  params
    datetime v_DATIM_TZ1 :IN ; datetime in timezone 1
    string   v_TZ1       :IN ; from timezone 1
    string   v_TZ2       :IN ; to timezone 2
  endparams
  variables
    datetime v_DATIM_TZM ; datetime "in the middle"
    datetime v_DATIM_TZ2 ; Convert datetime
    datetime v_DATIM2    ; 
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_R1,v_TZ_R2
  endvariables

  IF(v_TZ1=="") v_TZ1 = $nlstimezone
  IF(v_TZ2=="") v_TZ2 = $nlstimezone

  IF(v_TZ1==v_TZ2)
    RETURN(v_DATIM_TZ1)
  ENDIF

  ; How to check, is a timezone is valid?
  ; and $nlstimezonelist is to slow for just a simple test, or?
  ;
  v_TZ_R1 = $nlsinternaltime
  v_TZ_R2 = $nlstimezone

  ; TZ1=>UTC
  IF(v_TZ1=="UTC")
    v_DATIM_TZM = v_DATIM_TZ1
  ELSE
    ;convert datetime from TZ1 first from UTC=>TZ1 (wrong direction)
    ; Does not work properly for dates in transit "normal time" <-> "daylight saving time", but who cares!?!?!
    $nlsinternaltime = "UTC" ; from UTC
    $nlstimezone = v_TZ1     ; to timezone TZ1
    $$TL_DATIM_ISO2 = v_DATIM_TZ1
    v_TXT = "%%$$TL_DATIM_ISO2%%%"
    v_DATIM2 = v_TXT ; TZ1  
    v_DIFF = v_DATIM2-v_DATIM_TZ1 ; Difference (TZ1-UTC)
    ; Correct the calculation 
    v_DATIM_TZM = v_DATIM_TZ1 - v_DIFF ; TZM = TZ1-(TZ1-UTC) = UTC
  ENDIF

  ;v_DATIM_TZM is now UTC

  ; UTC=>TZ2
  IF(v_TZ2=="UTC")
    v_DATIM_TZ2 = v_DATIM_TZM
  ELSE
    v_TZ_R1 = $nlsinternaltime
    v_TZ_R2 = $nlstimezone
    $nlsinternaltime = "UTC" ; from UTC 
    $nlstimezone = v_TZ2     ; to timezone TZ2
    $$TL_DATIM_ISO2 = v_DATIM_TZM
    v_TXT = "%%$$TL_DATIM_ISO2%%%"
    v_DATIM_TZ2 = v_TXT ; TZ2
  ENDIF

  $nlsinternaltime = v_TZ_R1
  $nlstimezone = v_TZ_R2

  $status = 0
  RETURN(v_DATIM_TZ2)
END

Not jet solved

problem in transit between "normal" and "daylight saving" timezones
The procedure is slow(?) Will check (maybe) this with bigger testset

And as I said in last comment, this should be a task for the program language, as that can use directly the NLS-utilities and C/C++

Ingo

Anonymous
Forum|Forum|5 years ago
August 21, 2020

Hi Roger

Just trying to use $clock(<source>) with $nlstimezone

$nlsformat="classic"
$nlstimezone="classic"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="UTC"
v_TIME = $clock("180000")

$nlsformat="nlslocale"
$nlstimezone="CET"
v_TIME = $clock("180000")

$nlsformat="classic"
$nlstimezone="classic"

the result is always the same "180000"
How does $clock work with $nlstimezone?

9.4.01

Additional option for overriding the default behavior if the time zone has been defined (using $nlstimezone or $NLS_TIME_ZONE)

Ingo

Remarks to daylight saving:

Assume a datetime of "2020032901300000" (CET 29 march 2020, 1:30 am)
My default timetone is CET
To convert first I have to convert first to a dummy CET datetime to get the diff
$nlsinternaltime = "UTC"
$nlstimezone = "CET"
this gives me "2020032903300000" (CEST 29 march 2020, 3:30 am) *)
which is a diff of 2 hours
Now I subtract this diff from the original datetime
so the reuslt is "2020032811300000" (UCT 28 march 2020, 11:30 pm)
And this is wrong!
Correct would be
"2020032900300000" (UCT 29 march 2020, 0:30 am)
The problem is, that the dummy calculation is assuming, that the time is now in CEST and not CET
A solution would be to check, if the back conversion results in the old value, otherwise one have to adjust the diff ....

BTW:

$$TL_DATIM_ISO2 is a global datetime variable with format
"yyyymmddhhnnsstt"

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 22, 2020

Hi Freaks

Just a simple question 🙂
How to get the correct time from another timezone, if the day is not today?

Example:

I do have two timestamps, both created in germany

1) 2020101T180000 (1 january of 2020, 6 PM CET)
1) 2020501T180000 (1 may of 2020 , 6 PM CEST)

Now I want to convert them to UTC

The correct values would be:

1) 2020101T170000Z (1 january of 2020, 5 PM UTC)
1) 2020501T160000Z (1 may of 2020 , 4 PM UTC)

Problem is, that the difference is not a constant, but depends on "daylight saving"

With $nlstimezone set to UTC, I got only $datim as the currenct time in UTC

Any idea how to simple convert a timestamp to the correct time in another timezone?

Regards Ingo

So, here is a corrected version:

!!! crash, if a timzone is "CLASSIC" !!!

; Convert datetime(C=combined) from "timezone from" to "timezone to"
; $status
;  0  done, day is the same
;  1  done, day changed
; <0  error
ENTRY SF_TZ_CNV_C
  returns datetime
  params
    datetime v_DATIM_FROM :IN ; a datetime
    string   v_TZ_FROM    :IN ; timezone from
    string   v_TZ_TO      :IN ; timezone to
    string   v_PARA       :IN ; furher parameters if needed
  endparams
  variables
    datetime v_DATIM_UTC
    datetime v_DATIM_TO
    datetime v_DATIM_XUTC
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_MEM1,v_TZ_MEM2
    numeric  v_DD
    string   v_TMP
  endvariables

  IF(v_DATIM_FROM=="") 
    $status = 0
    RETURN("")
  ENDIF
  ;defaults
  IF(v_TZ_FROM=="") v_TZ_FROM = $nlstimezone
  IF(v_TZ_TO=="")   v_TZ_TO   = $nlstimezone

  ; make the function case independent
  v_TZ_FROM = $uppercase(v_TZ_FROM)
  v_TZ_TO   = $uppercase(v_TZ_TO)

  ; Convenience: Replace "Z" for "Zulu time" (used in XML) by "UTC"
  IF(v_TZ_FROM=="Z") v_TZ_FROM = "UTC"
  IF(v_TZ_TO=="Z")   v_TZ_TO   = "UTC"

  IF(v_TZ_FROM==v_TZ_TO) ; Nothing to do
    RETURN(v_DATIM_FROM)
  ENDIF

  IF(0) ; Check timezones (performance, as I got always the whole list of timezones?)
    getitem/id v_TMP,$nlstimezonelist,v_TZ_FROM
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone from '%%v_TZ_FROM%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
    getitem/id v_TMP,$nlstimezonelist,v_TZ_TO
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone to '%%v_TZ_TO%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
  ENDIF


  ; Memorize the old value
  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  IF(v_TZ_FROM=="UTC")
    v_DATIM_UTC = v_DATIM_FROM
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC
    $nlstimezone     = v_TZ_FROM           ; to timezone TZ_FROM
    $$TL_DATIM_ISO2 = v_DATIM_FROM
;!!! Crash if v_DATIM_FROM ="CLASSIC" !!!!
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_FROM / Format to "yyyymmddhhnnsstt"
    v_DATIM_XUTC = v_TXT                   ; TZ_FROM (wrong direction)
    v_DIFF = v_DATIM_XUTC-v_DATIM_FROM  ; Difference (TZ_FROM-UTC)
    v_DATIM_UTC = v_DATIM_FROM - v_DIFF ; TZ_FROM-(TZ_FROM-UTC) = UTC
  ENDIF

  ;v_DATIM_UTC is now UTC

  IF(v_TZ_TO=="UTC")
    v_DATIM_TO = v_DATIM_UTC
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC 
    $nlstimezone = v_TZ_TO                 ; to timezone TZ_TO
    $$TL_DATIM_ISO2 = v_DATIM_UTC
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_TO / Format to "yyyymmddhhnnsstt"
    v_DATIM_TO = v_TXT                     ; TZ_TO
  ENDIF

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2

  IF(v_DATIM_FROM[D]==v_DATIM_TO[D])
    $status = 0
  ELSE
    $status = 1
  ENDIF
  RETURN(v_DATIM_TO)
END ; SF_TZ_CNV_C]] >

Still the "bug" with the time at a transit "normal" ↔ "daylight saving"
And the check if the timezone is correct is switched off

Ingo

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 23, 2020

So, here is a corrected version:

!!! crash, if a timzone is "CLASSIC" !!!

; Convert datetime(C=combined) from "timezone from" to "timezone to"
; $status
;  0  done, day is the same
;  1  done, day changed
; <0  error
ENTRY SF_TZ_CNV_C
  returns datetime
  params
    datetime v_DATIM_FROM :IN ; a datetime
    string   v_TZ_FROM    :IN ; timezone from
    string   v_TZ_TO      :IN ; timezone to
    string   v_PARA       :IN ; furher parameters if needed
  endparams
  variables
    datetime v_DATIM_UTC
    datetime v_DATIM_TO
    datetime v_DATIM_XUTC
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_MEM1,v_TZ_MEM2
    numeric  v_DD
    string   v_TMP
  endvariables

  IF(v_DATIM_FROM=="") 
    $status = 0
    RETURN("")
  ENDIF
  ;defaults
  IF(v_TZ_FROM=="") v_TZ_FROM = $nlstimezone
  IF(v_TZ_TO=="")   v_TZ_TO   = $nlstimezone

  ; make the function case independent
  v_TZ_FROM = $uppercase(v_TZ_FROM)
  v_TZ_TO   = $uppercase(v_TZ_TO)

  ; Convenience: Replace "Z" for "Zulu time" (used in XML) by "UTC"
  IF(v_TZ_FROM=="Z") v_TZ_FROM = "UTC"
  IF(v_TZ_TO=="Z")   v_TZ_TO   = "UTC"

  IF(v_TZ_FROM==v_TZ_TO) ; Nothing to do
    RETURN(v_DATIM_FROM)
  ENDIF

  IF(0) ; Check timezones (performance, as I got always the whole list of timezones?)
    getitem/id v_TMP,$nlstimezonelist,v_TZ_FROM
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone from '%%v_TZ_FROM%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
    getitem/id v_TMP,$nlstimezonelist,v_TZ_TO
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone to '%%v_TZ_TO%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
  ENDIF


  ; Memorize the old value
  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  IF(v_TZ_FROM=="UTC")
    v_DATIM_UTC = v_DATIM_FROM
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC
    $nlstimezone     = v_TZ_FROM           ; to timezone TZ_FROM
    $$TL_DATIM_ISO2 = v_DATIM_FROM
;!!! Crash if v_DATIM_FROM ="CLASSIC" !!!!
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_FROM / Format to "yyyymmddhhnnsstt"
    v_DATIM_XUTC = v_TXT                   ; TZ_FROM (wrong direction)
    v_DIFF = v_DATIM_XUTC-v_DATIM_FROM  ; Difference (TZ_FROM-UTC)
    v_DATIM_UTC = v_DATIM_FROM - v_DIFF ; TZ_FROM-(TZ_FROM-UTC) = UTC
  ENDIF

  ;v_DATIM_UTC is now UTC

  IF(v_TZ_TO=="UTC")
    v_DATIM_TO = v_DATIM_UTC
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC 
    $nlstimezone = v_TZ_TO                 ; to timezone TZ_TO
    $$TL_DATIM_ISO2 = v_DATIM_UTC
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_TO / Format to "yyyymmddhhnnsstt"
    v_DATIM_TO = v_TXT                     ; TZ_TO
  ENDIF

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2

  IF(v_DATIM_FROM[D]==v_DATIM_TO[D])
    $status = 0
  ELSE
    $status = 1
  ENDIF
  RETURN(v_DATIM_TO)
END ; SF_TZ_CNV_C]] >

Still the "bug" with the time at a transit "normal" ↔ "daylight saving"
And the check if the timezone is correct is switched off

Ingo

So, a next version.
Hopefully without crash 🙂

;
;SF_TZ_CNV_C(,,,)
;
; Convert datetime(C=combined) from "timezone from" to "timezone to"
; $status
;  0  done, day is the same
;  1  done, day changed
; <0  error
;ENTRY SF_TZ_CNV_C
  returns datetime
  params
    datetime v_DATIM_FROM :IN ; a datetime
    string   v_TZ_FROM    :IN ; timezone from
    string   v_TZ_TO      :IN ; timezone to
    string   v_PARA       :IN ; furher parameters if needed
  endparams
  variables
    datetime v_DATIM_UTC
    datetime v_DATIM_TO
    datetime v_DATIM_XUTC
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_MEM1,v_TZ_MEM2
    numeric  v_DD
    string   v_TMP
  endvariables

  IF(v_DATIM_FROM=="") 
    $status = 0
    RETURN("")
  ENDIF
  ;defaults
  IF(v_TZ_FROM=="") v_TZ_FROM = $nlstimezone
  IF(v_TZ_TO=="")   v_TZ_TO   = $nlstimezone

  ; make the function case independent
  v_TZ_FROM = $uppercase(v_TZ_FROM)
  v_TZ_TO   = $uppercase(v_TZ_TO)

  ; if "CLASSIC" got the current, local  timezone
  ; else UnifAce will crash after 
  ;   $nlstimezone = "classic"
  ;   $$TL_DATIM_ISO2 = v_DATIM_FROM
  ;   v_TXT = "%%$$TL_DATIM_ISO2%%%"        ; <-Crash

  IF(v_TZ_FROM=="CLASSIC")
    v_TZ_FROM = $uppercase(SF_TZ_GET_LOC_TZ(""))
  ENDIF
  IF(v_TZ_TO=="CLASSIC")
    v_TZ_TO = $uppercase(SF_TZ_GET_LOC_TZ(""))
  ENDIF

  ; Convenience: Replace "Z" for "Zulu time" (used in XML) by "UTC"
  IF(v_TZ_FROM=="Z") v_TZ_FROM = "UTC"
  IF(v_TZ_TO=="Z")   v_TZ_TO   = "UTC"

  IF(v_TZ_FROM==v_TZ_TO) ; Nothing to do
    RETURN(v_DATIM_FROM)
  ENDIF

  IF(0) ; Check timezones (performance, as I got always the whole list of timezones?)
    getitem/id v_TMP,$nlstimezonelist,v_TZ_FROM
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone from '%%v_TZ_FROM%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
    getitem/id v_TMP,$nlstimezonelist,v_TZ_TO
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone to '%%v_TZ_TO%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
  ENDIF


  ; Memorize the old value
  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  IF(v_TZ_FROM=="UTC")
    v_DATIM_UTC = v_DATIM_FROM
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC
    $nlstimezone     = v_TZ_FROM           ; to timezone TZ_FROM
    $$TL_DATIM_ISO2 = v_DATIM_FROM
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_FROM / Format to "yyyymmddhhnnsstt"
    v_DATIM_XUTC = v_TXT                   ; TZ_FROM (wrong direction)
    v_DIFF = v_DATIM_XUTC-v_DATIM_FROM  ; Difference (TZ_FROM-UTC)
    v_DATIM_UTC = v_DATIM_FROM - v_DIFF ; TZ_FROM-(TZ_FROM-UTC) = UTC
  ENDIF

  ;v_DATIM_UTC is now UTC

  IF(v_TZ_TO=="UTC")
    v_DATIM_TO = v_DATIM_UTC
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC 
    $nlstimezone = v_TZ_TO                 ; to timezone TZ_TO
    $$TL_DATIM_ISO2 = v_DATIM_UTC
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_TO / Format to "yyyymmddhhnnsstt"
    v_DATIM_TO = v_TXT                     ; TZ_TO
  ENDIF

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2

  IF(v_DATIM_FROM[D]==v_DATIM_TO[D])
    $status = 0
  ELSE
    $status = 1
  ENDIF
  RETURN(v_DATIM_TO)
END ; SF_TZ_CNV_C

]] >

Roger Wallin
Participating Frequently
Forum|Forum|5 years ago
August 24, 2020

So, here is a corrected version:

!!! crash, if a timzone is "CLASSIC" !!!

; Convert datetime(C=combined) from "timezone from" to "timezone to"
; $status
;  0  done, day is the same
;  1  done, day changed
; <0  error
ENTRY SF_TZ_CNV_C
  returns datetime
  params
    datetime v_DATIM_FROM :IN ; a datetime
    string   v_TZ_FROM    :IN ; timezone from
    string   v_TZ_TO      :IN ; timezone to
    string   v_PARA       :IN ; furher parameters if needed
  endparams
  variables
    datetime v_DATIM_UTC
    datetime v_DATIM_TO
    datetime v_DATIM_XUTC
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_MEM1,v_TZ_MEM2
    numeric  v_DD
    string   v_TMP
  endvariables

  IF(v_DATIM_FROM=="") 
    $status = 0
    RETURN("")
  ENDIF
  ;defaults
  IF(v_TZ_FROM=="") v_TZ_FROM = $nlstimezone
  IF(v_TZ_TO=="")   v_TZ_TO   = $nlstimezone

  ; make the function case independent
  v_TZ_FROM = $uppercase(v_TZ_FROM)
  v_TZ_TO   = $uppercase(v_TZ_TO)

  ; Convenience: Replace "Z" for "Zulu time" (used in XML) by "UTC"
  IF(v_TZ_FROM=="Z") v_TZ_FROM = "UTC"
  IF(v_TZ_TO=="Z")   v_TZ_TO   = "UTC"

  IF(v_TZ_FROM==v_TZ_TO) ; Nothing to do
    RETURN(v_DATIM_FROM)
  ENDIF

  IF(0) ; Check timezones (performance, as I got always the whole list of timezones?)
    getitem/id v_TMP,$nlstimezonelist,v_TZ_FROM
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone from '%%v_TZ_FROM%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
    getitem/id v_TMP,$nlstimezonelist,v_TZ_TO
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone to '%%v_TZ_TO%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
  ENDIF


  ; Memorize the old value
  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  IF(v_TZ_FROM=="UTC")
    v_DATIM_UTC = v_DATIM_FROM
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC
    $nlstimezone     = v_TZ_FROM           ; to timezone TZ_FROM
    $$TL_DATIM_ISO2 = v_DATIM_FROM
;!!! Crash if v_DATIM_FROM ="CLASSIC" !!!!
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_FROM / Format to "yyyymmddhhnnsstt"
    v_DATIM_XUTC = v_TXT                   ; TZ_FROM (wrong direction)
    v_DIFF = v_DATIM_XUTC-v_DATIM_FROM  ; Difference (TZ_FROM-UTC)
    v_DATIM_UTC = v_DATIM_FROM - v_DIFF ; TZ_FROM-(TZ_FROM-UTC) = UTC
  ENDIF

  ;v_DATIM_UTC is now UTC

  IF(v_TZ_TO=="UTC")
    v_DATIM_TO = v_DATIM_UTC
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC 
    $nlstimezone = v_TZ_TO                 ; to timezone TZ_TO
    $$TL_DATIM_ISO2 = v_DATIM_UTC
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_TO / Format to "yyyymmddhhnnsstt"
    v_DATIM_TO = v_TXT                     ; TZ_TO
  ENDIF

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2

  IF(v_DATIM_FROM[D]==v_DATIM_TO[D])
    $status = 0
  ELSE
    $status = 1
  ENDIF
  RETURN(v_DATIM_TO)
END ; SF_TZ_CNV_C]] >

Still the "bug" with the time at a transit "normal" ↔ "daylight saving"
And the check if the timezone is correct is switched off

Ingo

Hi Ingo,
Thanks for the code.
Unfortunately I didn't get it working at first try.
What does
SF_TZ_GET_LOC_TZ("")
do?
How is the global parameter
$$TL_DATIM_ISO2
defined? Combined date and time, DIS(yyyymmddhhnnsstt)?

Regards RogerW.

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 24, 2020

So, here is a corrected version:

!!! crash, if a timzone is "CLASSIC" !!!

; Convert datetime(C=combined) from "timezone from" to "timezone to"
; $status
;  0  done, day is the same
;  1  done, day changed
; <0  error
ENTRY SF_TZ_CNV_C
  returns datetime
  params
    datetime v_DATIM_FROM :IN ; a datetime
    string   v_TZ_FROM    :IN ; timezone from
    string   v_TZ_TO      :IN ; timezone to
    string   v_PARA       :IN ; furher parameters if needed
  endparams
  variables
    datetime v_DATIM_UTC
    datetime v_DATIM_TO
    datetime v_DATIM_XUTC
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_MEM1,v_TZ_MEM2
    numeric  v_DD
    string   v_TMP
  endvariables

  IF(v_DATIM_FROM=="") 
    $status = 0
    RETURN("")
  ENDIF
  ;defaults
  IF(v_TZ_FROM=="") v_TZ_FROM = $nlstimezone
  IF(v_TZ_TO=="")   v_TZ_TO   = $nlstimezone

  ; make the function case independent
  v_TZ_FROM = $uppercase(v_TZ_FROM)
  v_TZ_TO   = $uppercase(v_TZ_TO)

  ; Convenience: Replace "Z" for "Zulu time" (used in XML) by "UTC"
  IF(v_TZ_FROM=="Z") v_TZ_FROM = "UTC"
  IF(v_TZ_TO=="Z")   v_TZ_TO   = "UTC"

  IF(v_TZ_FROM==v_TZ_TO) ; Nothing to do
    RETURN(v_DATIM_FROM)
  ENDIF

  IF(0) ; Check timezones (performance, as I got always the whole list of timezones?)
    getitem/id v_TMP,$nlstimezonelist,v_TZ_FROM
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone from '%%v_TZ_FROM%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
    getitem/id v_TMP,$nlstimezonelist,v_TZ_TO
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone to '%%v_TZ_TO%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
  ENDIF


  ; Memorize the old value
  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  IF(v_TZ_FROM=="UTC")
    v_DATIM_UTC = v_DATIM_FROM
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC
    $nlstimezone     = v_TZ_FROM           ; to timezone TZ_FROM
    $$TL_DATIM_ISO2 = v_DATIM_FROM
;!!! Crash if v_DATIM_FROM ="CLASSIC" !!!!
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_FROM / Format to "yyyymmddhhnnsstt"
    v_DATIM_XUTC = v_TXT                   ; TZ_FROM (wrong direction)
    v_DIFF = v_DATIM_XUTC-v_DATIM_FROM  ; Difference (TZ_FROM-UTC)
    v_DATIM_UTC = v_DATIM_FROM - v_DIFF ; TZ_FROM-(TZ_FROM-UTC) = UTC
  ENDIF

  ;v_DATIM_UTC is now UTC

  IF(v_TZ_TO=="UTC")
    v_DATIM_TO = v_DATIM_UTC
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC 
    $nlstimezone = v_TZ_TO                 ; to timezone TZ_TO
    $$TL_DATIM_ISO2 = v_DATIM_UTC
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_TO / Format to "yyyymmddhhnnsstt"
    v_DATIM_TO = v_TXT                     ; TZ_TO
  ENDIF

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2

  IF(v_DATIM_FROM[D]==v_DATIM_TO[D])
    $status = 0
  ELSE
    $status = 1
  ENDIF
  RETURN(v_DATIM_TO)
END ; SF_TZ_CNV_C]] >

Still the "bug" with the time at a transit "normal" ↔ "daylight saving"
And the check if the timezone is correct is switched off

Ingo

Hi Roger

Here the code for SF_TZ_GET_LOC_TZ
It "just" get the/a local timezone (first best timezone ID)
$$TZ_LOC_TZ is a simple string to hold the local ID.
As you can change the local timezone only by modifying the OS-time and/or by assignment setting this should by stable for a UnifAce session
And yes, $$TL_DATIM_ISO2 is "C" -type with DIS(yyyymmddhhnnsstt)

;
; SF_TZ_GET_LOC_TZ()
;
; Get the/a local timezone. 
;
  returns string
  params
    string  v_PARA:IN
  endparams
  variables
    datetime v_DATIM1
    datetime v_CUR_DATIM
    datetime v_DATIM1_L,v_DATIM1_H
    string   v_TZ_MEM1,v_TZ_MEM2
    string   v_LST
    string   v_ID
    string   v_DESC
  endvariables

  IF($$TZ_LOC_TZ!="")
    IF($$TZ_LOC_TZ=="·*ERR")
      $status = -2
      RETURN("")
    ELSE
      $status = 0 
      RETURN($$TZ_LOC_TZ)
    ENDIF
  ENDIF

  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  $nlsinternaltime = "classic"
  $nlstimezone     = "classic"
  v_DATIM1 = $datim
  v_DATIM1_L = v_DATIM1-1n
  v_DATIM1_H = v_DATIM1+1n
  v_LST = $nlstimezonelist
  FORLIST/id v_ID,v_DESC in v_LST
    IF($length(v_ID)<=3)
      $nlstimezone = v_ID
      v_CUR_DATIM = $datim
      IF(v_DATIM1_L<=v_CUR_DATIM && v_CUR_DATIM<=v_DATIM1_H)
        GOTO TAG_FOUND
      ENDIF
    ENDIF
  ENDFOR
  FORLIST/id v_ID,v_DESC in v_LST
    $nlstimezone = v_ID
    v_CUR_DATIM = $datim
    IF(v_DATIM1_L<=v_CUR_DATIM && v_CUR_DATIM<=v_DATIM1_H)
      GOTO TAG_FOUND
    ENDIF
  ENDFOR
  v_ID = ""
 TAG_FOUND:

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2


  IF(v_ID=="")
    $$TZ_LOC_TZ = "·*ERR"
    $status = -2
  ELSE
    $$TZ_LOC_TZ = v_ID
    $status = 0
  ENDIF
  RETURN(v_ID)
END ; SF_TZ_GET_LOC_TZ

Regards Ingo

Roger Wallin
Participating Frequently
Forum|Forum|5 years ago
August 25, 2020

So, here is a corrected version:

!!! crash, if a timzone is "CLASSIC" !!!

; Convert datetime(C=combined) from "timezone from" to "timezone to"
; $status
;  0  done, day is the same
;  1  done, day changed
; <0  error
ENTRY SF_TZ_CNV_C
  returns datetime
  params
    datetime v_DATIM_FROM :IN ; a datetime
    string   v_TZ_FROM    :IN ; timezone from
    string   v_TZ_TO      :IN ; timezone to
    string   v_PARA       :IN ; furher parameters if needed
  endparams
  variables
    datetime v_DATIM_UTC
    datetime v_DATIM_TO
    datetime v_DATIM_XUTC
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_MEM1,v_TZ_MEM2
    numeric  v_DD
    string   v_TMP
  endvariables

  IF(v_DATIM_FROM=="") 
    $status = 0
    RETURN("")
  ENDIF
  ;defaults
  IF(v_TZ_FROM=="") v_TZ_FROM = $nlstimezone
  IF(v_TZ_TO=="")   v_TZ_TO   = $nlstimezone

  ; make the function case independent
  v_TZ_FROM = $uppercase(v_TZ_FROM)
  v_TZ_TO   = $uppercase(v_TZ_TO)

  ; Convenience: Replace "Z" for "Zulu time" (used in XML) by "UTC"
  IF(v_TZ_FROM=="Z") v_TZ_FROM = "UTC"
  IF(v_TZ_TO=="Z")   v_TZ_TO   = "UTC"

  IF(v_TZ_FROM==v_TZ_TO) ; Nothing to do
    RETURN(v_DATIM_FROM)
  ENDIF

  IF(0) ; Check timezones (performance, as I got always the whole list of timezones?)
    getitem/id v_TMP,$nlstimezonelist,v_TZ_FROM
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone from '%%v_TZ_FROM%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
    getitem/id v_TMP,$nlstimezonelist,v_TZ_TO
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone to '%%v_TZ_TO%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
  ENDIF


  ; Memorize the old value
  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  IF(v_TZ_FROM=="UTC")
    v_DATIM_UTC = v_DATIM_FROM
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC
    $nlstimezone     = v_TZ_FROM           ; to timezone TZ_FROM
    $$TL_DATIM_ISO2 = v_DATIM_FROM
;!!! Crash if v_DATIM_FROM ="CLASSIC" !!!!
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_FROM / Format to "yyyymmddhhnnsstt"
    v_DATIM_XUTC = v_TXT                   ; TZ_FROM (wrong direction)
    v_DIFF = v_DATIM_XUTC-v_DATIM_FROM  ; Difference (TZ_FROM-UTC)
    v_DATIM_UTC = v_DATIM_FROM - v_DIFF ; TZ_FROM-(TZ_FROM-UTC) = UTC
  ENDIF

  ;v_DATIM_UTC is now UTC

  IF(v_TZ_TO=="UTC")
    v_DATIM_TO = v_DATIM_UTC
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC 
    $nlstimezone = v_TZ_TO                 ; to timezone TZ_TO
    $$TL_DATIM_ISO2 = v_DATIM_UTC
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_TO / Format to "yyyymmddhhnnsstt"
    v_DATIM_TO = v_TXT                     ; TZ_TO
  ENDIF

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2

  IF(v_DATIM_FROM[D]==v_DATIM_TO[D])
    $status = 0
  ELSE
    $status = 1
  ENDIF
  RETURN(v_DATIM_TO)
END ; SF_TZ_CNV_C]] >

Still the "bug" with the time at a transit "normal" ↔ "daylight saving"
And the check if the timezone is correct is switched off

Ingo

Hi Ingo,

The code is working now. Actually I don't need the code now, but one never knows.
The $nlstimezonelist doesn't seem to contain summer-time, ie. EET and CET are available but not EEST neither CEST. Perhaps that's natural as CEST is the same as EET and so on.....

Regards RogerW.

Ingo Stiller
Author
Participating Frequently
Forum|Forum|5 years ago
August 25, 2020

So, here is a corrected version:

!!! crash, if a timzone is "CLASSIC" !!!

; Convert datetime(C=combined) from "timezone from" to "timezone to"
; $status
;  0  done, day is the same
;  1  done, day changed
; <0  error
ENTRY SF_TZ_CNV_C
  returns datetime
  params
    datetime v_DATIM_FROM :IN ; a datetime
    string   v_TZ_FROM    :IN ; timezone from
    string   v_TZ_TO      :IN ; timezone to
    string   v_PARA       :IN ; furher parameters if needed
  endparams
  variables
    datetime v_DATIM_UTC
    datetime v_DATIM_TO
    datetime v_DATIM_XUTC
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_MEM1,v_TZ_MEM2
    numeric  v_DD
    string   v_TMP
  endvariables

  IF(v_DATIM_FROM=="") 
    $status = 0
    RETURN("")
  ENDIF
  ;defaults
  IF(v_TZ_FROM=="") v_TZ_FROM = $nlstimezone
  IF(v_TZ_TO=="")   v_TZ_TO   = $nlstimezone

  ; make the function case independent
  v_TZ_FROM = $uppercase(v_TZ_FROM)
  v_TZ_TO   = $uppercase(v_TZ_TO)

  ; Convenience: Replace "Z" for "Zulu time" (used in XML) by "UTC"
  IF(v_TZ_FROM=="Z") v_TZ_FROM = "UTC"
  IF(v_TZ_TO=="Z")   v_TZ_TO   = "UTC"

  IF(v_TZ_FROM==v_TZ_TO) ; Nothing to do
    RETURN(v_DATIM_FROM)
  ENDIF

  IF(0) ; Check timezones (performance, as I got always the whole list of timezones?)
    getitem/id v_TMP,$nlstimezonelist,v_TZ_FROM
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone from '%%v_TZ_FROM%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
    getitem/id v_TMP,$nlstimezonelist,v_TZ_TO
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone to '%%v_TZ_TO%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
  ENDIF


  ; Memorize the old value
  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  IF(v_TZ_FROM=="UTC")
    v_DATIM_UTC = v_DATIM_FROM
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC
    $nlstimezone     = v_TZ_FROM           ; to timezone TZ_FROM
    $$TL_DATIM_ISO2 = v_DATIM_FROM
;!!! Crash if v_DATIM_FROM ="CLASSIC" !!!!
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_FROM / Format to "yyyymmddhhnnsstt"
    v_DATIM_XUTC = v_TXT                   ; TZ_FROM (wrong direction)
    v_DIFF = v_DATIM_XUTC-v_DATIM_FROM  ; Difference (TZ_FROM-UTC)
    v_DATIM_UTC = v_DATIM_FROM - v_DIFF ; TZ_FROM-(TZ_FROM-UTC) = UTC
  ENDIF

  ;v_DATIM_UTC is now UTC

  IF(v_TZ_TO=="UTC")
    v_DATIM_TO = v_DATIM_UTC
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC 
    $nlstimezone = v_TZ_TO                 ; to timezone TZ_TO
    $$TL_DATIM_ISO2 = v_DATIM_UTC
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_TO / Format to "yyyymmddhhnnsstt"
    v_DATIM_TO = v_TXT                     ; TZ_TO
  ENDIF

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2

  IF(v_DATIM_FROM[D]==v_DATIM_TO[D])
    $status = 0
  ELSE
    $status = 1
  ENDIF
  RETURN(v_DATIM_TO)
END ; SF_TZ_CNV_C]] >

Still the "bug" with the time at a transit "normal" ↔ "daylight saving"
And the check if the timezone is correct is switched off

Ingo

HI Roger
CET "includes" CEST 🙂
IF you convert CET↔UTC you will see, that the difference is 2 hours i.e CET actual is CEST
BTW: The abrevations CET, CEST, EET, ... are just convenience names but not "official".
Ingo

Roger Wallin
Participating Frequently
Forum|Forum|5 years ago
August 25, 2020

So, here is a corrected version:

!!! crash, if a timzone is "CLASSIC" !!!

; Convert datetime(C=combined) from "timezone from" to "timezone to"
; $status
;  0  done, day is the same
;  1  done, day changed
; <0  error
ENTRY SF_TZ_CNV_C
  returns datetime
  params
    datetime v_DATIM_FROM :IN ; a datetime
    string   v_TZ_FROM    :IN ; timezone from
    string   v_TZ_TO      :IN ; timezone to
    string   v_PARA       :IN ; furher parameters if needed
  endparams
  variables
    datetime v_DATIM_UTC
    datetime v_DATIM_TO
    datetime v_DATIM_XUTC
    numeric  v_DIFF
    string   v_TXT
    string   v_TZ_MEM1,v_TZ_MEM2
    numeric  v_DD
    string   v_TMP
  endvariables

  IF(v_DATIM_FROM=="") 
    $status = 0
    RETURN("")
  ENDIF
  ;defaults
  IF(v_TZ_FROM=="") v_TZ_FROM = $nlstimezone
  IF(v_TZ_TO=="")   v_TZ_TO   = $nlstimezone

  ; make the function case independent
  v_TZ_FROM = $uppercase(v_TZ_FROM)
  v_TZ_TO   = $uppercase(v_TZ_TO)

  ; Convenience: Replace "Z" for "Zulu time" (used in XML) by "UTC"
  IF(v_TZ_FROM=="Z") v_TZ_FROM = "UTC"
  IF(v_TZ_TO=="Z")   v_TZ_TO   = "UTC"

  IF(v_TZ_FROM==v_TZ_TO) ; Nothing to do
    RETURN(v_DATIM_FROM)
  ENDIF

  IF(0) ; Check timezones (performance, as I got always the whole list of timezones?)
    getitem/id v_TMP,$nlstimezonelist,v_TZ_FROM
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone from '%%v_TZ_FROM%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
    getitem/id v_TMP,$nlstimezonelist,v_TZ_TO
    IF($status<=0)
      putmess "SF_TZ_CNV_C:Timezone to '%%v_TZ_TO%%%' is not a vaild timezone!"
      $status = 
      RETURN("")
    ENDIF
  ENDIF


  ; Memorize the old value
  v_TZ_MEM1 = $nlsinternaltime
  v_TZ_MEM2 = $nlstimezone

  IF(v_TZ_FROM=="UTC")
    v_DATIM_UTC = v_DATIM_FROM
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC
    $nlstimezone     = v_TZ_FROM           ; to timezone TZ_FROM
    $$TL_DATIM_ISO2 = v_DATIM_FROM
;!!! Crash if v_DATIM_FROM ="CLASSIC" !!!!
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_FROM / Format to "yyyymmddhhnnsstt"
    v_DATIM_XUTC = v_TXT                   ; TZ_FROM (wrong direction)
    v_DIFF = v_DATIM_XUTC-v_DATIM_FROM  ; Difference (TZ_FROM-UTC)
    v_DATIM_UTC = v_DATIM_FROM - v_DIFF ; TZ_FROM-(TZ_FROM-UTC) = UTC
  ENDIF

  ;v_DATIM_UTC is now UTC

  IF(v_TZ_TO=="UTC")
    v_DATIM_TO = v_DATIM_UTC
  ELSE
    $nlsinternaltime = "UTC"               ; from UTC 
    $nlstimezone = v_TZ_TO                 ; to timezone TZ_TO
    $$TL_DATIM_ISO2 = v_DATIM_UTC
    v_TXT = "%%$$TL_DATIM_ISO2%%%"         ; Convert UTC->TZ_TO / Format to "yyyymmddhhnnsstt"
    v_DATIM_TO = v_TXT                     ; TZ_TO
  ENDIF

  $nlsinternaltime = v_TZ_MEM1
  $nlstimezone     = v_TZ_MEM2

  IF(v_DATIM_FROM[D]==v_DATIM_TO[D])
    $status = 0
  ELSE
    $status = 1
  ENDIF
  RETURN(v_DATIM_TO)
END ; SF_TZ_CNV_C]] >

Still the "bug" with the time at a transit "normal" ↔ "daylight saving"
And the check if the timezone is correct is switched off

Ingo

I converted
UTC 25.1.2020 10:01
UTC 25.8.2020 10:01
to CET.
Nice, now I understand your comment "CET includes CEST".

Regards RogerW.

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