[fpc-pascal] date formating dificulty

[Philippe]

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/YYYY', now)
returns 18-11-2014 and not 18/11/2014 ? strtodate( formatDateTime(
'DD/MM/YYYY', 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"/"yyyy'
> 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.

> Thanks for your answer. It is a good start.
 As you wrote it
is not a good pratice to do so. ... So I can repeat part of the
question! ... Where can I find tutorial wh

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> 
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> 


Links:
------
[1]
http://www.freepascal.org/docs-html/rtl/sysutils/strtodate.html
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