Adding Time

[dgoss]

I have searched and searched but don't seem to get anywhere. All i'm after doing is to add X number of hours/minutes to current datetime to give a start date and time.
i.e> 26/04/2013 17:30
add 45Hrs
start date and time = 28/04/2013 14:30
It looks simple enough to do but i really am struggling to get my head into it:sign0104:

 

[Erel]

You should check DateUtils. First search result:
Basic4android Search: add time

 

[dgoss]

thx erel. Had a look at dateutils. Sorry to say but i must admit i of a look of boy lost in the woods about me.:sign0085:Any pointers will greatly appreciated as i am new to this.:sign0013:

 

[Mahares]

I built this function that calculates a new date and time after a certain number of hours and minutes were added to or subtracted from a given date and time. I tested it and it seems to work correctly forward and backward. Hopefully, Erel can check it out and give his blessings:

Msgbox(NewDateTime("26/04/2013", "17:30",45,0),"")  'returns 28/04/2013 14:30
Msgbox(NewDateTime("26/04/2013", "17:30",-45,0),"")  'returns 24/04/2013 20:30

Sub NewDateTime(StartDate As String, StartTime As String, HrsToAdd As Int, MnsToAdd As Int ) As String
   Dim OrigDateFormat,OrigTimeFormat As String
   Dim NewT As Long
   Dim D As Int 
   If HrsToAdd > 0 Then
      D=Floor(HrsToAdd/24)
   Else
      D=Ceil(HrsToAdd/24)
   End If
   Dim H As Int=HrsToAdd Mod 24
   OrigDateFormat=DateTime.Dateformat   'store original date format
   OrigTimeFormat=DateTime.TimeFormat   'store original time format
   DateTime.DateFormat="dd/MM/yyyy"
   DateTime.TimeFormat="HH:mm"
   NewT=DateTime.Add(DateTime.DateTimeParse(StartDate, StartTime),0,0,D) 
   NewT=NewT+ H*DateTime.TicksPerHour + MnsToAdd*DateTime.TicksPerMinute 'add the ticks for the hours and mns added
   Return DateTime.Date(NewT) & " " & DateTime.Time(NewT)
   DateTime.Dateformat=OrigDateFormat  'Revert back to original date format
   DateTime.Timeformat=OrigTimeFormat  'Revert back to original time format
End Sub

 

[Erel]

I strongly recommend you to use DateUtils for such calculations. These calculations are MUCH more complicated than it may first seem.

Dim p As Period
p.Hours = 10 'add 10 hours
p.Minutes = 35 'and 35 minutes
Dim newDate As Long = DateUtils.AddPeriod(DateTime.Now, p)
Log(DateUtils.TicksToString(newDate))

 

[Mahares]

@Erel: Your code works well. It yields the same result as my function does. The only problem is: Every time you need a time or date calculation you have to add the code module (extra baggage). Perhaps consider embedding it in a future core function library.

 

[Erel]

Your code is wrong. You assume that there are 24 hours on each day. It will fail on the days that the DST starts or ends.

You can compile the module into a library and then add it to your project if you like to. Or you can just add the module, right click on the tab and choose Hide module.

 

[dgoss]

Sorry took so long to reply but i'm doing this on the road and internet is a bit sketchy at best of times.
Thx Mahares will have a look at your code but i think i'l go with dateutils now that i know how to use properly. many thx to Erel for pointing me in the right direction.