Re: [fpc-pascal] date formating dificulty
Em 18.11.2014 10:27, Michael Van Canneyt escreveu:
> On Tue, 18
Nov 2014, Philippe wrote:
>
>> Em 18.11.2014 09:49, Philippe escreveu:
I wrote a program: - windows 8 32 bits - lazarus 1.2.4 ... fpc 2.6.4
then I copied it to another computer - windows 7 64 bits - lazarus
1.0.14 fpc 2.6.2 and got into trouble with dates format! programs
behave diferent way, and what was working on the fisrt computer does not
work properly in the second! I guess I need some tutorial (I looked for
but did not find anything :( !) why formatDateTime( 'DD/MM/', now)
returns 18-11-2014 and not 18/11/2014 ? strtodate( formatDateTime(
'DD/MM/', now)) works ok on the w 8 32 bits, but arise an exception
on the w 7 64 bits. I am confused with the following syntax function
FormatDateTime( const FormatStr: string; DateTime: TDateTime; const
FormatSettings: TFormatSettings ):string; how does it work between two
format especifications: FormatStr and FormatSettings ? appreciate any
example of good programming pratise of data formating to avoid bad
surprise moving program from an OS to another ! Philippe on
http://www.freepascal.org/docs-html/rtl/sysutils/strtodate.html [1] I
found Program Example19; { This program demonstrates the StrToDate
function } Uses sysutils; Procedure TestStr (S : String); begin Writeln
(S,' : ',DateToStr(StrToDate(S))); end; Begin Writeln ('ShortDateFormat
',ShortDateFormat); TestStr(DateTimeToStr(Date));
TestStr('05'+DateSeparator+'05'+DateSeparator+'1999');
TestStr('5'+DateSeparator+'5'); TestStr('5'); End. the compiler warns
that ShortDateFormat is deprecated ... which is not informed in the doc
...
>
> It should be, I will check.
>
> Anyway, as Graeme hinted:
ShortDateFormat contains a format string, and / is a placeholder for the
date
> separator character on the computer on which the program is
running.
>
> If you want to force a character, you can enclose it in
quotes:
> ShortDateFormat:='dd"/"mm"/"'
> will always use / as the
date separator, no matter what the internatonalization settings on the
PC.
>
> But it is bad practice to do so.
>
> Secondly, it is a common
mistake to think that StrToDate will always correctly perform the
opposite of DateToStr.
> It does not, but this is documented.
>
>
Michael.
>
> I still don't know how to use at the same time formatStr
and FormatSettings in FormatDateTime.
>
> 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
>
> Thanks
>
> ___
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- fpc-pascal@lists.freepascal.org
>
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal [2]
Links:
--
[1]
http://www.freepascal.org/docs-html/rtl/sysutils/strtodate.html
[2]
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
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Re: [fpc-pascal] date formating dificulty
Em 19.11.2014 12:17, Philippe escreveu:
> Em 18.11.2014 10:27,
Michael Van Canneyt escreveu:
>
>> On Tue, 18 Nov 2014, Philippe
wrote:
>>
>>> Em 18.11.2014 09:49, Philippe escreveu: I wrote a
program: - windows 8 32 bits - lazarus 1.2.4 ... fpc 2.6.4 then I copied
it to another computer - windows 7 64 bits - lazarus 1.0.14 fpc
2.6.2 and got into trouble with dates format! programs behave diferent
way, and what was working on the fisrt computer does not work properly
in the second! I guess I need some tutorial (I looked for but did not
find anything :( !) why formatDateTime( 'DD/MM/', now) returns
18-11-2014 and not 18/11/2014 ? strtodate( formatDateTime( 'DD/MM/',
now)) works ok on the w 8 32 bits, but arise an exception on the w 7 64
bits. I am confused with the following syntax function FormatDateTime(
const FormatStr: string; DateTime: TDateTime; const FormatSettings:
TFormatSettings ):string; how does it work between two format
especifications: FormatStr and FormatSettings ? appreciate any example
of good programming pratise of data formating to avoid bad surprise
moving program from an OS to another ! Philippe on
http://www.freepascal.org/docs-html/rtl/sysutils/strtodate.html [1] I
found Program Example19; { This program demonstrates the StrToDate
function } Uses sysutils; Procedure TestStr (S : String); begin Writeln
(S,' : ',DateToStr(StrToDate(S))); end; Begin Writeln ('ShortDateFormat
',ShortDateFormat); TestStr(DateTimeToStr(Date));
TestStr('05'+DateSeparator+'05'+DateSeparator+'1999');
TestStr('5'+DateSeparator+'5'); TestStr('5'); End. the compiler warns
that ShortDateFormat is deprecated ... which is not informed in the doc
...
>>
>> It should be, I will check.
>>
>> Anyway, as Graeme hinted:
ShortDateFormat contains a format string, and / is a placeholder for the
date
>> separator character on the computer on which the program is
running.
>>
>> If you want to force a character, you can enclose it in
quotes:
>> ShortDateFormat:='dd"/"mm"/"'
>> will always use / as the
date separator, no matter what the internatonalization settings on the
PC.
>>
>> But it is bad practice to do so.
>>
>> Secondly, it is a
common mistake to think that StrToDate will always correctly perform the
opposite of DateToStr.
>> It does not, but this is documented.
>>
>>
Michael.
>>
>> I still don't know how to use at the same time formatStr
and FormatSettings in FormatDateTime.
>>
>> 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
>>
>>
Thanks
>>
>> interesting stuff ... but ... out of date using
deprecatings ... (from year 2000 !!!) ... does not help much!!!
>>
>>
http://www.math.uni-leipzig.de/pool/tuts/FreePascal/units/node21.html#SECTION002141000
>>
>> ___
>> fpc-pascal
maillist - fpc-pascal@lists.freepascal.org
>>
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal [2]
>
>
___
> fpc-pascal maillist -
fpc-pascal@lists.freepascal.org
>
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal [2]
Links:
--
[1]
http://www.freepascal.org/docs-html/rtl/sysutils/strtodate.html
[2]
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
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Re: [fpc-pascal] date formating dificulty
On Wed, 19 Nov 2014, Philippe wrote:
Em 19.11.2014 12:17, Philippe escreveu:
Em 18.11.2014 10:27, Michael Van Canneyt escreveu:
On Tue, 18 Nov 2014, Philippe wrote:
Em 18.11.2014 09:49, Philippe escreveu: I wrote a program: -
windows 8 32 bits - lazarus 1.2.4 ... fpc 2.6.4 then I copied it to another
computer - windows 7 64 bits - lazarus 1.0.14 fpc 2.6.2
and got into trouble with dates format! programs behave diferent way, and what
was working on the fisrt computer does not work properly in
the second! I guess I need some tutorial (I looked for but did not find
anything :( !) why formatDateTime( 'DD/MM/', now) returns
18-11-2014 and not 18/11/2014 ? strtodate( formatDateTime( 'DD/MM/',
now)) works ok on the w 8 32 bits, but arise an exception on
the w 7 64 bits. I am confused with the following syntax function
FormatDateTime( const FormatStr: string; DateTime:
TDateTime; const FormatSettings: TFormatSettings ):string; how does it work
between two format especifications: FormatStr and
FormatSettings ? appreciate any example of good programming pratise of data
formating to
avoid bad surprise moving program from an OS to another !
Philippe on http://www.freepascal.org/docs-html/rtl/sysutils/strtodate.html I
found Program Example19; { This program demonstrates the
StrToDate function } Uses sysutils; Procedure TestStr (S : String); begin
Writeln
(S,' : ',DateToStr(StrToDate(S))); end; Begin Writeln
('ShortDateFormat ',ShortDateFormat); TestStr(DateTimeToStr(Date));
TestStr('05'+DateSeparator+'05'+DateSeparator+'1999');
TestStr('5'+DateSeparator+'5'); TestStr('5'); End. the compiler warns that
ShortDateFormat is deprecated ... which is not informed in
the doc ...
It should be, I will check.
Anyway, as Graeme hinted: ShortDateFormat contains a format string, and / is a placeholder for the date
separator character on the computer on which the program is running.
If you want to force a character, you can enclose it in quotes:
ShortDateFormat:='dd"/"mm"/"'
will always use / as the date separator, no matter what the internatonalization
settings on the PC.
But it is bad practice to do so.
Secondly, it is a common mistake to think that StrToDate will always correctly
perform the opposite of DateToStr.
It does not, but this is documented.
Michael.
I still don't know how to use at the same time formatStr and FormatSettings in
FormatDateTime.
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
Good practice is to avoid converting to and from string the whole time.
If you need to store a timestamp, use the ISO 8601 format or RFC 3339 (or is it
3999?).
Regarding formatsettings:
Since some versions, most date/time/money/float formatting routines support
passing a TFormatSettings record to it to control the formatting.
(this is mostly done for multi-threaded apps where different threads can have
different settings, like in web-apps).
If no TFormatSettings record is passed, the global FormatSettings record is
used.
The various format variables which existed prior to this change,
have simply been moved to this global FormatSettings record, with some backwards compatibility code.
So if you had old code that did something like:
ShortDateStr:='dd/mm/';
you should now use
FormatSettings.ShortDateStr:='dd/mm/';
That is all there is to it. Hardly worth a tutorial.
But if you have suggestions for the documentation, I will be glad to add them.
Michael.___
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Re: [fpc-pascal] date formating dificulty
On 2014-11-19 20:04, Michael Van Canneyt wrote:
> If you need to store a timestamp, use the ISO 8601 format or RFC 3339 (or is
> it 3999?).
I can't agree more!!
Snippet from tiOPF code
{ Summary of ISO 8601 http://www.cl.cam.ac.uk/~mgk25/iso-time.html }
cIntlDateTimeStor = 'mmdd"T"hhnnss';// for storage
cIntlDateTimeDisp = '-mm-dd hh:nn:ss'; // for display
CIntlDateDisp = '-mm-dd'; // for display
See tiIntlDateDispAsDateTime(), tiIntlDateStorAsDateTime() in tiOPF's
tiUtils.pas unit.
I even store TDateTime data as cIntlDateTimeStor formatted strings in
databases. Never had an issue with date conversions since.
Regards,
- Graeme -
--
fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal
http://fpgui.sourceforge.net/
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Re: [fpc-pascal] date formating dificulty
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 = May
ShortDaysddd = Thu
LongDays = Thursday
ShortDate d = 5/6/2049
LongDate dd = Thursday, May 06, 2049
AMPM hhampm = 01AM
ShortTime t = 1:02
LongTime tt = 1:02:03
2DigitCentury dd/mm/ = 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 = JUNE
ShortDaysddd = SUN
LongDays = SUNDAY
ShortDate d = 05-JUN-49
LongDate dd = SUNDAY 05 of JUNE of 1949
AMPM hhampm = 01morning
ShortTime t = 01_02_03
LongTime tt = 01 _ 02 _ 03 . 004
2DigitCentury dd/mm/ = 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 = '+FormatDateTime('', myDate));
// Use ShortDayNames
WriteLn(' ShortDaysddd = '+FormatDateTime('ddd', myDate));
// Use LongDayNames
WriteLn(' LongDays = '+FormatDateTime('', myDate));
// Use the ShortDateFormat string
WriteLn(' ShortDate d = '+FormatDateTime('d', myDate));
// Use the LongDateFormat string
WriteLn(' LongDate dd = '+FormatDateTime('dd', 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/ = '+FormatDateTime('dd/mm/',
myDate));
WriteLn('');
WriteLn('Modified formatting:');
// Now chan
Re: [fpc-pascal] date formating dificulty
Em 19.11.2014 19:31, waldo kitty escreveu:
> 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 [1]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 =
May
> ShortDays ddd = Thu
> LongDays = Thursday
> ShortDate d =
5/6/2049
> LongDate dd = Thursday, May 06, 2049
> AMPM hhampm =
01AM
> ShortTime t = 1:02
> LongTime tt = 1:02:03
> 2DigitCentury
dd/mm/ = 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 = JUNE
> ShortDays
ddd = SUN
> LongDays = SUNDAY
> ShortDate d = 05-JUN-49
>
LongDate dd = SUNDAY 05 of JUNE of 1949
> AMPM hhampm = 01morning
>
ShortTime t = 01_02_03
> LongTime tt = 01 _ 02 _ 03 . 004
>
2DigitCentury dd/mm/ = 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 =
'+FormatDateTime('', myDate));
>
> // Use ShortDayNames
> WriteLn('
ShortDays ddd = '+FormatDateTime('ddd', myDate));
>
> // Use
LongDayNames
> WriteLn(' LongDays = '+FormatDateTime('',
myDate));
>
> // Use the ShortDateFormat string
> WriteLn(' ShortDate
d = '+FormatDateTime('d', myDate));
>
> // Use the
LongDateFormat string
> WriteLn(' LongDate dd =
'+FormatDateTime('dd', 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/ =
'+FormatDateTime('dd/mm/',
> myDate));
>
> WriteLn('');
>
WriteLn('Modified formatting:');
>
> // Now change the defaults
>
DefaultFormatSettings.DateSeparator := '-';
>
DefaultFormatSettings.TimeSeparator := '_';
>
DefaultFormatSettings.ShortDateFormat := 'dd/mmm/yy';
>
DefaultFormatSettings.LongDateFormat := ' dd "of" "of" ';
>
DefaultFormatSettings.TimeAMString := 'morning';
>
DefaultFormatSettings.TimePMString := 'afternoon'
