Re: [Gambas-user] Format function changes date value

[George]

Tobi,

Thanks for the pointer to that thread.  I had tried searching the message
archives, but I probably didn't find it since I was looking for bugs
related to the Format function.

I did try changing CDate(...) to Date(...), but it didn't change my
results.  I had also tried an implicit conversion, but again I get the same
results.

What's important for me to know is that the current behavior is considered
correct, so I can allow for it in my code.  I was initially hesitant to
kludge a fix, only to have it broken again by a subsequent Gambas fix, but
it doesn't appear that will be a problem.

Thank you!

-George


On Sat, May 19, 2018 at 1:52 PM, Tobias Boege  wrote:

> On Sat, 19 May 2018, George wrote:
> > > CDate uses UTC and, without the time information in the string, it
> would
> > store midnight. Format uses local time.
> >
> > That is definitely part of the issue.  My local time is GMT-04, and
> here's
> > what I get when specifying the time in my test:
> >
> > Test date: 5/4/2018 03:59:00 Formatted: 05/03/18 Thu
> > Test date: 5/4/2018 04:00:00 Formatted: 05/04/18 Fri
> >
> > However, if I look at time in the results, the difference isn't exactly
> the
> > offset:
> > Test date: 5/4/2018 03:59:00 Formatted: 05/03/18 23:05:00  Difference:
> > 4:54:00
> > Test date: 5/4/2018 04:00:00 Formatted: 05/04/18 00:05:00  Difference:
> > 3:55:00
> > Test date: 5/4/2018 00:00:00 Formatted: 05/03/18 20:05:00  Difference:
> > 3:55:00
> >
> > The offset isn't an even number of hours. What's also odd is that this
> was
> > never a problem before about a week ago.  This code is many years old,
> and
> > the problem suddenly began occurring with compiled code.
> >
>
> This has been discussed multiple times recently, the last time was [1].
> So let me elaborate on T Lee's answer a bit. The official statement is
> that the previous behaviour was a bug which was unfortunately not
> discovered sooner. As of Gambas 3.11, you should remember that CStr()
> and CDate(), being low-level conversions, assume UTC, i.e. they convert
> the date "literally" (without any offset) to a date and a time integer,
> which is the internal representation of a Date in Gambas.
>
> The higher-level Str(), Val(), Format() and Date() functions take the
> current locale into account. Mixing CDate() with Format() is almost always
> a bug, as one honours the local timezone and the other doesn't. CDate()
> produces a Date object which is 05/04/18 00:00 UTC but when you format
> it using Format$(), you get a string representing the same point in time
> relative to your current timezone. I'm in GMT+0200 these days so I get:
>
>   Test date: 5/4/2018 Formatted: 05/04/18 02:00 Fri
>
> Removing the "C" from the invocation of CDate(), you chain locale-aware
> functions only and get the desired result:
>
>   Test date: 5/4/2018 Formatted: 05/04/18 00:00 Fri
>
> That five minute offset you mention is indeed weird, though, and I have
> no explanation for that.
>
> Regards,
> Tobi
>
> [1] https://lists.gambas-basic.org/pipermail/user/2018-May/064153.html
>
> --
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>
> 
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Re: [Gambas-user] Format function changes date value

[Tobias Boege]

On Sat, 19 May 2018, George wrote:
> > CDate uses UTC and, without the time information in the string, it would
> store midnight. Format uses local time.
> 
> That is definitely part of the issue.  My local time is GMT-04, and here's
> what I get when specifying the time in my test:
> 
> Test date: 5/4/2018 03:59:00 Formatted: 05/03/18 Thu
> Test date: 5/4/2018 04:00:00 Formatted: 05/04/18 Fri
> 
> However, if I look at time in the results, the difference isn't exactly the
> offset:
> Test date: 5/4/2018 03:59:00 Formatted: 05/03/18 23:05:00  Difference:
> 4:54:00
> Test date: 5/4/2018 04:00:00 Formatted: 05/04/18 00:05:00  Difference:
> 3:55:00
> Test date: 5/4/2018 00:00:00 Formatted: 05/03/18 20:05:00  Difference:
> 3:55:00
> 
> The offset isn't an even number of hours. What's also odd is that this was
> never a problem before about a week ago.  This code is many years old, and
> the problem suddenly began occurring with compiled code.
> 

This has been discussed multiple times recently, the last time was [1].
So let me elaborate on T Lee's answer a bit. The official statement is
that the previous behaviour was a bug which was unfortunately not
discovered sooner. As of Gambas 3.11, you should remember that CStr()
and CDate(), being low-level conversions, assume UTC, i.e. they convert
the date "literally" (without any offset) to a date and a time integer,
which is the internal representation of a Date in Gambas.

The higher-level Str(), Val(), Format() and Date() functions take the
current locale into account. Mixing CDate() with Format() is almost always
a bug, as one honours the local timezone and the other doesn't. CDate()
produces a Date object which is 05/04/18 00:00 UTC but when you format
it using Format$(), you get a string representing the same point in time
relative to your current timezone. I'm in GMT+0200 these days so I get:

  Test date: 5/4/2018 Formatted: 05/04/18 02:00 Fri

Removing the "C" from the invocation of CDate(), you chain locale-aware
functions only and get the desired result:

  Test date: 5/4/2018 Formatted: 05/04/18 00:00 Fri

That five minute offset you mention is indeed weird, though, and I have
no explanation for that.

Regards,
Tobi

[1] https://lists.gambas-basic.org/pipermail/user/2018-May/064153.html

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Re: [Gambas-user] Format function changes date value

[George]

I noticed a post from Benoît in another thread that this mailing list has
been deprecated, so I'm going to repost this in u...@lists.gambas-basic.org



On Sat, May 19, 2018 at 1:20 PM, George  wrote:

> > CDate uses UTC and, without the time information in the string, it would
> store midnight. Format uses local time.
>
> That is definitely part of the issue.  My local time is GMT-04, and here's
> what I get when specifying the time in my test:
>
> Test date: 5/4/2018 03:59:00 Formatted: 05/03/18 Thu
> Test date: 5/4/2018 04:00:00 Formatted: 05/04/18 Fri
>
> However, if I look at time in the results, the difference isn't exactly
> the offset:
> Test date: 5/4/2018 03:59:00 Formatted: 05/03/18 23:05:00  Difference:
> 4:54:00
> Test date: 5/4/2018 04:00:00 Formatted: 05/04/18 00:05:00  Difference:
> 3:55:00
> Test date: 5/4/2018 00:00:00 Formatted: 05/03/18 20:05:00  Difference:
> 3:55:00
>
> The offset isn't an even number of hours. What's also odd is that this was
> never a problem before about a week ago.  This code is many years old, and
> the problem suddenly began occurring with compiled code.
>
>
> On Sat, May 19, 2018 at 10:15 AM, Gianluigi  wrote:
>
>> But Debug (Print) localizes!
>>
>> However, with the dates I always get lost :-(
>>
>> Regards
>> Gianluigi
>>
>>
>> 2018-05-19 16:00 GMT+02:00 T Lee Davidson :
>>
>> > CDate uses UTC and, without the time information in the string, it would
>> > store midnight. Format uses local time.
>> >
>> > So, anyone in a time zone behind UTC will get the previous day printed.
>> > Try this format string:
>> > zTestResult = Format(CDate(zTestDate), "mm/dd/yy hh:nn ddd")
>> >
>> > Does the difference in hours match your timezone offset?
>> >
>> >
>> > --
>> > Lee
>> >
>> >
>> > On 05/19/2018 09:08 AM, Gianluigi wrote:
>> > > I think it depends on your version of Gambas, I get the correct result
>> > with
>> > > the master:
>> > >
>> > >   Dim zTestDate As String
>> > >   Dim zTestResult As String
>> > >   zTestDate = "5/4/2018"
>> > >   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
>> > >   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
>> > >   '' Result: Main.Main.9: Test date: 5/4/2018 Formatted: 05/04/18 ven
>> > >
>> > > Regards
>> > > Gianluigi
>> >
>> > 
>> > --
>> > Check out the vibrant tech community on one of the world's most
>> > engaging tech sites, Slashdot.org! http://sdm.link/slashdot
>> > ___
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>> > https://lists.sourceforge.net/lists/listinfo/gambas-user
>> >
>> 
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>
>
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Re: [Gambas-user] Format function changes date value

[George]

> CDate uses UTC and, without the time information in the string, it would
store midnight. Format uses local time.

That is definitely part of the issue.  My local time is GMT-04, and here's
what I get when specifying the time in my test:

Test date: 5/4/2018 03:59:00 Formatted: 05/03/18 Thu
Test date: 5/4/2018 04:00:00 Formatted: 05/04/18 Fri

However, if I look at time in the results, the difference isn't exactly the
offset:
Test date: 5/4/2018 03:59:00 Formatted: 05/03/18 23:05:00  Difference:
4:54:00
Test date: 5/4/2018 04:00:00 Formatted: 05/04/18 00:05:00  Difference:
3:55:00
Test date: 5/4/2018 00:00:00 Formatted: 05/03/18 20:05:00  Difference:
3:55:00

The offset isn't an even number of hours. What's also odd is that this was
never a problem before about a week ago.  This code is many years old, and
the problem suddenly began occurring with compiled code.


On Sat, May 19, 2018 at 10:15 AM, Gianluigi  wrote:

> But Debug (Print) localizes!
>
> However, with the dates I always get lost :-(
>
> Regards
> Gianluigi
>
>
> 2018-05-19 16:00 GMT+02:00 T Lee Davidson :
>
> > CDate uses UTC and, without the time information in the string, it would
> > store midnight. Format uses local time.
> >
> > So, anyone in a time zone behind UTC will get the previous day printed.
> > Try this format string:
> > zTestResult = Format(CDate(zTestDate), "mm/dd/yy hh:nn ddd")
> >
> > Does the difference in hours match your timezone offset?
> >
> >
> > --
> > Lee
> >
> >
> > On 05/19/2018 09:08 AM, Gianluigi wrote:
> > > I think it depends on your version of Gambas, I get the correct result
> > with
> > > the master:
> > >
> > >   Dim zTestDate As String
> > >   Dim zTestResult As String
> > >   zTestDate = "5/4/2018"
> > >   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
> > >   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
> > >   '' Result: Main.Main.9: Test date: 5/4/2018 Formatted: 05/04/18 ven
> > >
> > > Regards
> > > Gianluigi
> >
> > 
> > --
> > Check out the vibrant tech community on one of the world's most
> > engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> > ___
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> >
> 
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Re: [Gambas-user] Format function changes date value

[Gianluigi]

But Debug (Print) localizes!

However, with the dates I always get lost :-(

Regards
Gianluigi


2018-05-19 16:00 GMT+02:00 T Lee Davidson :

> CDate uses UTC and, without the time information in the string, it would
> store midnight. Format uses local time.
>
> So, anyone in a time zone behind UTC will get the previous day printed.
> Try this format string:
> zTestResult = Format(CDate(zTestDate), "mm/dd/yy hh:nn ddd")
>
> Does the difference in hours match your timezone offset?
>
>
> --
> Lee
>
>
> On 05/19/2018 09:08 AM, Gianluigi wrote:
> > I think it depends on your version of Gambas, I get the correct result
> with
> > the master:
> >
> >   Dim zTestDate As String
> >   Dim zTestResult As String
> >   zTestDate = "5/4/2018"
> >   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
> >   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
> >   '' Result: Main.Main.9: Test date: 5/4/2018 Formatted: 05/04/18 ven
> >
> > Regards
> > Gianluigi
>
> 
> --
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Re: [Gambas-user] Format function changes date value

[T Lee Davidson]

CDate uses UTC and, without the time information in the string, it would store 
midnight. Format uses local time.

So, anyone in a time zone behind UTC will get the previous day printed. Try 
this format string:
zTestResult = Format(CDate(zTestDate), "mm/dd/yy hh:nn ddd")

Does the difference in hours match your timezone offset?


-- 
Lee


On 05/19/2018 09:08 AM, Gianluigi wrote:
> I think it depends on your version of Gambas, I get the correct result with
> the master:
> 
>   Dim zTestDate As String
>   Dim zTestResult As String
>   zTestDate = "5/4/2018"
>   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
>   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
>   '' Result: Main.Main.9: Test date: 5/4/2018 Formatted: 05/04/18 ven
> 
> Regards
> Gianluigi

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Re: [Gambas-user] Format function changes date value

[Gianluigi]

It also works with Gambas 3.11.2

'' Main.Main.9: Test date: 5/4/2018 00:00:00 Formatted: 05/04/18 ven

Regards
Gianluigi


2018-05-19 15:36 GMT+02:00 George :

> Sorry, I should have added that I'm on version 3.11.2
>
> On Sat, May 19, 2018 at 9:27 AM, George  wrote:
>
> > I'm using the repository 'http://ppa.launchpad.net/
> > gambas-team/gambas3/ubuntu'
> >
> > Is there something that's more up-to-date?
> >
> > On Sat, May 19, 2018 at 9:08 AM, Gianluigi  wrote:
> >
> >> I think it depends on your version of Gambas, I get the correct result
> >> with
> >> the master:
> >>
> >>   Dim zTestDate As String
> >>   Dim zTestResult As String
> >>   zTestDate = "5/4/2018"
> >>   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
> >>   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
> >>   '' Result: Main.Main.9: Test date: 5/4/2018 Formatted: 05/04/18 ven
> >>
> >> Regards
> >> Gianluigi
> >>
> >> 2018-05-19 14:54 GMT+02:00 George :
> >>
> >> > When using the Format function to format a date, the date gets offset
> >> by 1
> >> > day.  Here's an example:
> >> >
> >> >   Dim zTestDate As String
> >> >   Dim zTestResult As String
> >> >   zTestDate = "5/4/2018"
> >> >   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
> >> >   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
> >> >
> >> > Result: Test date: 5/4/2018 Formatted: 05/03/18 Thu
> >> >
> >> > This seems to have started since the last update was applied.
> >> > 
> >> > --
> >> > Check out the vibrant tech community on one of the world's most
> >> > engaging tech sites, Slashdot.org! http://sdm.link/slashdot
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> >> >
> >> 
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> >>
> >
> >
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Re: [Gambas-user] Format function changes date value

[George]

I'm using the repository '
http://ppa.launchpad.net/gambas-team/gambas3/ubuntu'

Is there something that's more up-to-date?

On Sat, May 19, 2018 at 9:08 AM, Gianluigi  wrote:

> I think it depends on your version of Gambas, I get the correct result with
> the master:
>
>   Dim zTestDate As String
>   Dim zTestResult As String
>   zTestDate = "5/4/2018"
>   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
>   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
>   '' Result: Main.Main.9: Test date: 5/4/2018 Formatted: 05/04/18 ven
>
> Regards
> Gianluigi
>
> 2018-05-19 14:54 GMT+02:00 George :
>
> > When using the Format function to format a date, the date gets offset by
> 1
> > day.  Here's an example:
> >
> >   Dim zTestDate As String
> >   Dim zTestResult As String
> >   zTestDate = "5/4/2018"
> >   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
> >   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
> >
> > Result: Test date: 5/4/2018 Formatted: 05/03/18 Thu
> >
> > This seems to have started since the last update was applied.
> > 
> > --
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> >
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Re: [Gambas-user] Format function changes date value

[Gianluigi]

I think it depends on your version of Gambas, I get the correct result with
the master:

  Dim zTestDate As String
  Dim zTestResult As String
  zTestDate = "5/4/2018"
  zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
  Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
  '' Result: Main.Main.9: Test date: 5/4/2018 Formatted: 05/04/18 ven

Regards
Gianluigi

2018-05-19 14:54 GMT+02:00 George :

> When using the Format function to format a date, the date gets offset by 1
> day.  Here's an example:
>
>   Dim zTestDate As String
>   Dim zTestResult As String
>   zTestDate = "5/4/2018"
>   zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
>   Debug "Test date: " & zTestDate & " Formatted: " & zTestResult
>
> Result: Test date: 5/4/2018 Formatted: 05/03/18 Thu
>
> This seems to have started since the last update was applied.
> 
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[Gambas-user] Format function changes date value

[George]

When using the Format function to format a date, the date gets offset by 1
day.  Here's an example:

  Dim zTestDate As String
  Dim zTestResult As String
  zTestDate = "5/4/2018"
  zTestResult = Format(CDate(zTestDate), "mm/dd/yy ddd")
  Debug "Test date: " & zTestDate & " Formatted: " & zTestResult

Result: Test date: 5/4/2018 Formatted: 05/03/18 Thu

This seems to have started since the last update was applied.
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