[Gambas-user] Format function changes date value

[Gianluigi]

2018-06-07 17:12 GMT+02:00 Benoît Minisini <g4mba5 at gmail.com>:

> Le 07/06/2018 à 16:51, Gianluigi a écrit :
>
>> I wrote it even if I imagined it was wrong (it works here), I'm sorry.
>> It's useless, with the dates I still do not understand anything.
>> These coming days, I will try to write a my wiki to and submit it to your
>> judgment.
>>
>> Regards
>> Gianluigi
>>
>>
> I try to explain again:
>
> 1) Date & times are internally represented in UTC date. See them as a
> number of days since an absolute instant in the past. You can get this
> number with CFloat(AnyDate). The integer part is the number of days, the
> fractional part is the part of the day (the precision is the millisecond).
>
> 2) Each time you read or you write a date & time as a string, you *must*
> know the timezone associated with the string representation. *But* this
> timezone is implicit, as it is not written inside the string representation
> (something that I should add to Gambas).
>
> In other words, "2018/6/7" *cannot* represent an absolute time instant. It
> depends on the implicit timezone.
>
> 3) So, all Gambas functions that deal with date & time as a string *must*
> assume a timezone. Some functions assume UTC timezone, and others assume
> local timezone. Normally, all documentation pages on the wiki says which
> one is used.
>
> Is it clearer now?
>
> --
> Benoît Minisini
>
>
Hi Benoit,
sorry for the delay, I had to go out.
The difference between local and UTC is clear to me.
I find it difficult to memorize, to fix well in my mind, to fully
understand the translation into the string.
Suppose we have a CUsers class where I store user data including the date
of birth.
Suppose I use this class as an array:
   hObj = New CUsers (iId, sName, sSurName, dDate, ...)
   $hGlobalObject.Add(hObj)
If I have to save the date in an ini file like Settings and I want to be
sure that I do not have problems, how do I translate the date to be saved
into a string, and then how can I re-translate it into a date format from
ini?
So I'm in confusion, I would use CStr and then CDate to stay in UTC and
then display the dates with Format.
I know I'm an idiot, and I'll continue to use a database...

Regards
Gianluigi


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