Referenz Zeitzone ohne Sommer/Winterzeit ?

[hitzi]

Und im umgedrehten Fall so:

Delphi-Quellcode:

[...]
interface

function TzSpecificLocalTimeToSystemTime(lpTimeZoneInformation: PTimeZoneInformation;
  var lpLocalTime, lpUniversalTime: TSystemTime): BOOL; stdcall;
{$EXTERNALSYM TzSpecificLocalTimeToSystemTime}

function LocalDateTimeToUTC(aLocal : TDateTime) : TDateTime;

[...]

implementation

function TzSpecificLocalTimeToSystemTime; external kernel32 name 'TzSpecificLocalTimeToSystemTime';

function LocalDateTimeToUTC(aLocal : TDateTime) : TDateTime;
var
  tzi : TIME_ZONE_INFORMATION;
  utc : TSystemTime;
  localtime : TSystemTime;
begin
  DateTimeToSystemTime(aLocal, localtime);
  GetTimeZoneInformation(tzi);
  TzSpecificLocalTimeToSystemTime(@tzi, localtime, utc);
  Result := SystemTimeToDateTime(utc);
end;  

[...]