Android Question Date problem with 29th October

[BobsYourUncle]

Hi,

When I add 28 or 29 days to the 1st October, I get the same result of 29th October! Works fine adding to the 1st September.

Example code below. Any ideas what's going on?

Dim StartOfMonth As Long
Dim Date1 As Long
Dim Date2 As Long
 
DateTime.DateFormat = "dd-MM-yyyy"
 
StartOfMonth = DateTime.DateParse("01-10-2017") 
 
Date1 = StartOfMonth + (DateTime.TicksPerDay * 28)
Date2 = StartOfMonth + (DateTime.TicksPerDay * 29)
 
Log(DateTime.Date(Date1)) 'Result 29-10-2017
Log(DateTime.Date(Date2)) 'Result 29-10-2017

 

[DonManfred]

You should use Period and add it to the Date.

https://www.b4x.com/android/help/dateutils.html

    Dim StartOfMonth As Long
    Dim Date1 As Long
    Dim Date2 As Long
    DateTime.DateFormat = "dd-MM-yyyy"
    StartOfMonth = DateTime.DateParse("01-10-2017")

    Dim p1 As Period
    Dim p2 As Period
    p1.Initialize
    p1.Days = 28
    p2.Initialize
    p2.Days = 29
    Date1 = DateUtils.AddPeriod(StartOfMonth,p1)
    Date2 = DateUtils.AddPeriod(StartOfMonth,p2)

    Log(DateTime.Date(Date1)) 'Result 29-10-2017
    Log(DateTime.Date(Date2)) 'Result 30-10-2017

Logger verbunden mit: 9885e6514556383552
--------- beginning of crash
--------- beginning of main
--------- beginning of system
*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
29-10-2017
30-10-2017
** Activity (main) Resume **
** Activity (main) Pause, UserClosed = false **
** Activity (main) Resume **

 

[JordiCP]

Perhaps, as per your locale settings, it is taking into account the winter hour change (-1) that will take place precisely on October 29th at 03:00:00 (at least this is in most of Europe I think)

So, 1/10/2017 (let's suppose it assumes at 00:00:00) + 28 days ---> 29/10/2017 at 00:00:00
1/10/2017 (let's suppose it assumes at 00:00:00) + 29 days ---> 30/10/2017 at 00:00:00 minus 1hour --> 29/10/2017 at 23:00:00

to me it makes some sense.

 

[BobsYourUncle]

Thanks for such a quick reply Manfred. Your code works a treat!

You should use Period and add it to the Date.

https://www.b4x.com/android/help/dateutils.html

    Dim StartOfMonth As Long
    Dim Date1 As Long
    Dim Date2 As Long
    DateTime.DateFormat = "dd-MM-yyyy"
    StartOfMonth = DateTime.DateParse("01-10-2017")

    Dim p1 As Period
    Dim p2 As Period
    p1.Initialize
    p1.Days = 28
    p2.Initialize
    p2.Days = 29
    Date1 = DateUtils.AddPeriod(StartOfMonth,p1)
    Date2 = DateUtils.AddPeriod(StartOfMonth,p2)

    Log(DateTime.Date(Date1)) 'Result 29-10-2017
    Log(DateTime.Date(Date2)) 'Result 30-10-2017

 

[BobsYourUncle]

Yes! That does make sense! Thank you. (I guess the AddPeriod function @DonManfred mentions takes this into account somehow).

Perhaps, as per your locale settings, it is taking into account the winter hour change (-1) that will take place precisely on October 29th at 03:00:00 (at least this is in most of Europe I think)

So, 1/10/2017 (let's suppose it assumes at 00:00:00) + 28 days ---> 29/10/2017 at 00:00:00
1/10/2017 (let's suppose it assumes at 00:00:00) + 29 days ---> 30/10/2017 at 00:00:00 minus 1hour --> 29/10/2017 at 23:00:00

to me it makes some sense.