program STD_TIME { Written for Delphi 3 : DCC32 -cc } ;

{ I have only been able to test this in the UK, during winter time.

  Scan windows.pas for TTimeZoneInformation,
  see Win32 Help via index for TIME_ZONE_INFORMATION.

  I suspect an error in Win32 Help, since the transition times
  look as if in Local not GMT; and in the data, as UK/EU changes
  are both at 0100h GMT.

  Redirect output to temporary BAT file, and execute.  Needs Win32.
  }

uses Windows, SysUtils ;


function ItIs(const T : TDateTime) : string ;
var Yr, Mo, Dy, H, M, S, C : word ;
begin DecodeDate(T, Yr, Mo, Dy) ; DecodeTime(T, H, M, S, C) ;
  Result := Format('%d-%2.2d-%2.2dT%2.2d:%2.2d:%2.2d',
    [Yr, Mo, Dy, H, M, S]) end {ItIs} ;


const TZID : array [0..2] of string [21] = ('TIME_ZONE_ID_UNKNOWN',
  'TIME_ZONE_ID_STANDARD', 'TIME_ZONE_ID_DAYLIGHT') ;

var GTZI : cardinal ; TZI : TTimeZoneInformation ;
CMJD, MJD, time_t : integer ; T : TDateTime ; 


BEGIN ;
Writeln(':: STD_TIME  (c) www.merlyn.demon.co.uk >= 2005-02-27',
  '  See Win32 Help') ;

GTZI := GetTimeZoneInformation(TZI) ;
Write(':: According to Windows:  GTZI = ', GTZI, '  =>  ') ;

if GTZI=TIME_ZONE_ID_INVALID then Writeln('TIME_ZONE_ID_INVALID.') 
  else with TZI do begin
  Writeln(TZID[GTZI]) ;

  T := Now ;
  Writeln(':: "Now" = ', ItIs(T), ' local time =>') ;
  CMJD := Trunc(T)+15018 ;
  Write(':: Local CMJD = ', CMJD) ;
  case GTZI of
    {TIME_ZONE_ID_UNKNOWN}  0 : T := 0 ;
    {TIME_ZONE_ID_STANDARD} 1 : T := T + StandardBias/1440 ;
    {TIME_ZONE_ID_DAYLIGHT} 2 : T := T + DaylightBias/1440 ;
    end ;
  MJD := Trunc(T)+15018 ;
  Writeln('  True MJD = ', MJD, '  GMT = ', ItIs(T)) ;
  time_t := Trunc(86400*(T-EncodeDate(1970, 1, 1))) ;
  Writeln(':: UNIX time_t = ', time_t, ' sec, from 1970-01-01 00:00:00 GMT.') ;
  Writeln('SET CMJD=', CMJD:1) ;
  Writeln('SET MJD=', MJD:1) ;
  Writeln('SET GMT=', ItIs(T)) ;
  Writeln('SET time_t=', time_t) ;
  end { w TZI } ;

END.