[fpc-pascal] date formating dificulty

[waldo kitty]

On 11/19/2014 9:17 AM, Philippe wrote:
>> I still don't know how to use at the same time formatStr and FormatSettings in FormatDateTime.

i'm not sure i understand your delima... perhaps you are trying to determine how 
the FormatSettings work and how you can force the same output format on 
different OSes? i found the following (slightly modified by me for CLI) delphi 
code that might help... the original code resides at 
http://www.delphibasics.co.uk/RTL.asp?Name=FormatDateTime

in the code, we output the results of the various FormatDateTime usages... then 
we change the values of the date and time formatting variables and run the same 
outputs again...

>> I´ll like very much to find a tutorial or some example about the good
>> practice to manage dates and be sure it will do the same thing on different
>> machines ....

in some cases, you can fall back to delphi tutorials... it can be troublesome in 
some cases where things are slightly different between FPC/Lazarus and Delphi... 
the biggest problem i personally run into is that so much example code is GUI 
oriented and i still code for CLI...

anyway, here is the output of the following code...

*NOTE:* i think we've found a bug in (fpc?) trunk or perhaps it is just an 
unexpected side effect due to the system's settings... the day and month are 
reversed in the first separators line... as the comments in the code note, we're 
trying to work with 5 Jun 49... but this output was done on a US winwhatever 
(vista) system... it might be getting in the way by forcing mm/dd/yy format from 
the dd/mm/yy work string... someone else will have to speak to that as i would 
expect it to do the same in the second output set but it doesn't...


System formatting:
   Working with date string     = 05/06/49 01:02:03.004
   Separators dd/mm/yy hh:nn:ss = 06/05/49 01:02:03
   ShortMonths              mmm = May
   LongMonths              mmmm = May
   ShortDays                ddd = Thu
   LongDays                dddd = Thursday
   ShortDate              ddddd = 5/6/2049
   LongDate              dddddd = Thursday, May 06, 2049
   AMPM                  hhampm = 01AM
   ShortTime                  t = 1:02
   LongTime                  tt = 1:02:03
   2DigitCentury     dd/mm/yyyy = 06/05/2049

Modified formatting:
   Working with date string     = 05-06-49 01_02_03.004
   Separators dd/mm/yy hh:nn:ss = 05-06-49 01_02_03
   ShortMonths              mmm = JUN
   LongMonths              mmmm = JUNE
   ShortDays                ddd = SUN
   LongDays                dddd = SUNDAY
   ShortDate              ddddd = 05-JUN-49
   LongDate              dddddd = SUNDAY 05 of JUNE of 1949
   AMPM                  hhampm = 01morning
   ShortTime                  t = 01_02_03
   LongTime                  tt = 01 _ 02 _ 03 . 004
   2DigitCentury     dd/mm/yyyy = 05-06-1949


===== snip =====
program DTFormatting;

uses SysUtils;

var
   DateStr : String;
   myDate  : TDateTime;

begin
   // Set up our TDateTime variable with a full date and time :
   // 5th of June 2049 at 01:02:03.004  (.004 milli-seconds)
   //
   // Note that 49 is treated as 2049 as follows :
   //               TwoDigitYearCenturyWindow => 50
   //                            Current year => 2008 (at time of writing)
   //      Subtract TwoDigitYearCenturyWindow => 1958
   //            2 digit year to be converted => 49
   //  Compare with the last 2 digits of 1958 => Less
   //      So the year is in the next century => 2049
   // (58 would be converted to 1958)

   WriteLn('System formatting:');

   DateStr := '05/06/49 01:02:03.004';
   WriteLn('  Working with date string     = '+DateStr);

   myDate := StrToDateTime(DateStr);

   // Demonstrate default locale settings

   // Use the DateSeparator and TimeSeparator values
   WriteLn('  Separators dd/mm/yy hh:nn:ss = '+FormatDateTime('dd/mm/yy 
hh:nn:ss', myDate));

   // Use ShortMonthNames
   WriteLn('  ShortMonths              mmm = '+FormatDateTime('mmm', myDate));

   // Use LongMonthNames
   WriteLn('  LongMonths              mmmm = '+FormatDateTime('mmmm', myDate));

   // Use ShortDayNames
   WriteLn('  ShortDays                ddd = '+FormatDateTime('ddd', myDate));

   // Use LongDayNames
   WriteLn('  LongDays                dddd = '+FormatDateTime('dddd', myDate));

   // Use the ShortDateFormat string
   WriteLn('  ShortDate              ddddd = '+FormatDateTime('ddddd', myDate));

   // Use the LongDateFormat string
   WriteLn('  LongDate              dddddd = '+FormatDateTime('dddddd', myDate));

   // Use the TimeAmString
   WriteLn('  AMPM                  hhampm = '+FormatDateTime('hhampm', myDate));

   // Use the ShortTimeFormat string
   WriteLn('  ShortTime                  t = '+FormatDateTime('t', myDate));

   // Use the LongTimeFormat string
   WriteLn('  LongTime                  tt = '+FormatDateTime('tt', myDate));

   // Use the TwoDigitCenturyWindow
   WriteLn('  2DigitCentury     dd/mm/yyyy = '+FormatDateTime('dd/mm/yyyy', 
myDate));

   WriteLn('');
   WriteLn('Modified formatting:');

   // Now change the defaults
   DefaultFormatSettings.DateSeparator      := '-';
   DefaultFormatSettings.TimeSeparator      := '_';
   DefaultFormatSettings.ShortDateFormat    := 'dd/mmm/yy';
   DefaultFormatSettings.LongDateFormat     := 'dddd dd "of" mmmm "of" yyyy';
   DefaultFormatSettings.TimeAMString       := 'morning';
   DefaultFormatSettings.TimePMString       := 'afternoon';
   DefaultFormatSettings.ShortTimeFormat    := 'hh:nn:ss';
   DefaultFormatSettings.LongTimeFormat     := 'hh : nn : ss . zzz';
   DefaultFormatSettings.ShortMonthNames[6] := 'JUN';
   DefaultFormatSettings.LongMonthNames[6]  := 'JUNE';
   DefaultFormatSettings.ShortDayNames[1]   := 'SUN';
   DefaultFormatSettings.LongDayNames[1]    := 'SUNDAY';
   DefaultFormatSettings.TwoDigitYearCenturyWindow := 75; // This means 49 is 
treated as 1949

   // Set up our TDateTime variable with the same value as before
   // **except that we must use the new date and time separators**
   // The TwoDigitYearCenturyWindow variable only takes effect here
   DateStr := '05-06-49 01_02_03.004';
   WriteLn('  Working with date string     = '+DateStr);

   myDate := StrToDateTime(DateStr);

   // Use the DateSeparator and TimeSeparator values
   WriteLn('  Separators dd/mm/yy hh:nn:ss = '+FormatDateTime('dd/mm/yy 
hh:nn:ss', myDate));

   // Use ShortMonthNames
   WriteLn('  ShortMonths              mmm = '+FormatDateTime('mmm', myDate));

   // Use LongMonthNames
   WriteLn('  LongMonths              mmmm = '+FormatDateTime('mmmm', myDate));

   // Use ShortDayNames
   WriteLn('  ShortDays                ddd = '+FormatDateTime('ddd', myDate));

   // Use LongDayNames
   WriteLn('  LongDays                dddd = '+FormatDateTime('dddd', myDate));

   // Use the ShortDateFormat string
   WriteLn('  ShortDate              ddddd = '+FormatDateTime('ddddd', myDate));

   // Use the LongDateFormat string
   WriteLn('  LongDate              dddddd = '+FormatDateTime('dddddd', myDate));

   // Use the TimeAmString
   WriteLn('  AMPM                  hhampm = '+FormatDateTime('hhampm', myDate));

   // Use the ShortTimeFormat string
   WriteLn('  ShortTime                  t = '+FormatDateTime('t', myDate));

   // Use the LongTimeFormat string
   WriteLn('  LongTime                  tt = '+FormatDateTime('tt', myDate));

   // Use the TwoDigitCenturyWindow
   WriteLn('  2DigitCentury     dd/mm/yyyy = '+FormatDateTime('dd/mm/yyyy', 
myDate));
end.
===== snip =====

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