Android Question Displaying the time between 2 events

[Derek Johnson]

I've was trying to display the time between 2 events in hours, minutes and seconds using this type of code

Sub TestSub
    Dim  t1, t2 As Long

    t1=DateTime.now
    Sleep(5000)
    t2=DateTime.now

    Log("Elapsed time: " & DateTime.time(t2-t1))
End Sub

I expected this to display:

Elapsed time: 00:00:05​

but instead it displayed:

Elapsed time: 01:00:05
​

So the duration displayed an extra hour.

My Local time is currently GMT (CST) and DateTime.TimeZoneOffset =0

Time(0) shows as Thu 01 Jan 1970 01:00:00

Is this the expected result?

Derek

 

[Mahares]

I expected this to display:
Elapsed time: 00:00:05

Your code should be like this:

t1=DateTime.now
    Sleep(5000)
    t2=DateTime.now
    Dim p As Period
    p=DateUtils.PeriodBetweenInDays(t1,t2)
    Log($"${p.Days} days ${p.Hours} hours  ${p.Minutes} min   ${p.Seconds} sec"$) '0 days 0 hours  0 min   5 sec

and if you want more precise formatting:

Log($"${p.Days}:$2.0{p.Hours}:$2.0{p.Minutes}:$2.0{p.Seconds}"$)   '0:00:00:05
    Log($"$2.0{p.Hours}:$2.0{p.Minutes}:$2.0{p.Seconds}"$)   '00:00:05

 

[Erel]

DateTime.TimeZoneOffset =0

Whenever you need to set the time zone to 0 you can be sure that you are doing something wrong.

 

[Derek Johnson]

Whenever you need to set the time zone to 0 you can be sure that you are doing something wrong.

Yes that's probably true, but I wasn't setting the Time Zone, my Nexus 5X was reporting that the DateTime.TimeZoneOffset was 0.

What seems wrong is that

    DateTime.DateFormat="EEE dd MMM YYYY HH:mm:ss"
    Log("Time Zero " & DateTime.Date(0))

on my Nexus 5X produces

Time Zero Thu 01 Jan 1970 01:00:00

whereas my understanding is that Unix Time starts at

01 Jan 1970 00:00:00 CST

I tried this on another device and it produced

Time Zero Thu 01 Jan 1970 00:00:00

so this may be a problem specific to my Nexus 5X.

Could anyone else try this on a Nexus 5X please?


Derek

 

[Erel]

Ticks = Number of milliseconds since 1/1/1970 00:00 UTC

The short and correct answer is: never use DateTime.Date or DateTime.Time with a value that represents anything other than ticks. Milliseconds <> Ticks.
Code to convert milliseconds to string: https://www.b4x.com/android/forum/threads/summing-times.85302/#post-540422

Long answer:

Source: https://en.wikipedia.org/wiki/British_Summer_Time

"An inquiry during the winter of 1959–60, in which 180 national organisations were consulted, revealed a slight preference for a change to all-year GMT+1, but instead the length of summer time was extended as a trial.[9] A further inquiry during 1966–67 led the government of Harold Wilson to introduce the British Standard Time experiment, with Britain remaining on GMT+1 throughout the year. This took place between 27 October 1968 and 31 October 1971, when there was a reversion to the previous arrangement."

This means that the time in UK at 1/1/1970 00:00 UTC was 01:00.

 

[Derek Johnson]

Erel,

Thanks for taking the time to reply to that. That definitely explains it! I'm constantly surprised by the complexity of time related issues.

Weird!

Derek