_DateDiff() and $sType usage - return the total time difference

[mLipok]

Documentation for 

_DateDiff()

says:

Quote

$sType

One of the following: D = Difference in days between the given dates M = Difference in months between the given dates Y = Difference in years between the given dates w = Difference in Weeks between the given dates h = Difference in hours between the given dates n = Difference in minutes between the given dates s = Difference in seconds between the given dates

And today, for the first time, I noticed that this function lacks (at least for me) one possibility -  return the total time difference in the format in which the start and end dates were given.

Do you have any way or do you see here on the forum an working example which will return such results:

_DateDiff('full', "2021/09/01 08:00:00", "2021/09/01 15:58:00") ; >>> "0000/00/00 07:58:00"
_DateDiff('full', "2021/09/01 08:00:00", "2021/09/05 15:58:00") ; >>> "0000/00/05 07:58:00"
_DateDiff('full', "2021/01/01 08:00:00", "2021/09/05 15:58:00") ; >>> "0000/09/05 07:58:00"
_DateDiff('full', "2020/01/01 08:00:00", "2021/09/05 15:58:00") ; >>> "0001/09/05 07:58:00"

 
I will try to answer the standard questions asked in such cases:

• I haven't done anything myself yet, I just have a concept in my head, but I wanted to see if something like this had been done before.
• Yes I tried to find this solution here on the forum for about 1 hour.

Regards,
@mLipok

 

 

EDIT:
I rolled up my sleeves and set to work on solving this problem. So far I have something like in the following snippet:

Func _DateDiff_FullTime($sStartDate, $sEndDate)
    Local $iSeconds = _DateDiff('s', $sStartDate, $sEndDate)
    Local $sDate = _DateAdd('s', $iSeconds, '1000/01/01 00:00:00')
    Local $asTimePart[4]
    Local $asDatePart[4]
    _DateTimeSplit($sDate, $asDatePart, $asTimePart)
    Local $iYear = $asDatePart[1], $iMonth = $asDatePart[2], $iDay = $asDatePart[3]
    Local $iHours = $asTimePart[1], $iMins = $asTimePart[2], $iSecs = $asTimePart[3]
    $iYear = Number($iYear) - 1
    $iMonth = Number($iMonth) - 1
    $iDay = Number($iDay) - 1
    Local $sFullTimeDifference = '0000' & '/' & $iMonth & '/' & $iDay & ' ' & $iHours & ':' & $iMins & ':' & $iSecs
    ConsoleWrite("! $sFullTimeDifference = " & $sFullTimeDifference & @CRLF)
    Return $sFullTimeDifference
EndFunc   ;==>_DateDiff_FullTime

I know it's not perfect yet, but I'm working on it. If I encounter a problem, I will ask additional questions, and when I finish, I will share the result.
I'm going back to work.

Now it produce such example results (not related to the opening example )

Quote

! $sFullTimeDifference = 0000/0/0 10:17:53
! $sFullTimeDifference = 0000/11/30 13:47:4
! $sFullTimeDifference = 0000/11/30 10:43:54
! $sFullTimeDifference = 0000/0/1 0:40:11
! $sFullTimeDifference = 0000/11/30 11:1:14

 

Edited September 10, 2021 by mLipok

[jchd]

The standard for date format is ISO-8601, which also specifies how to espress durations. For instance, year 0000 doesn't exist which makes your output an invalid ISO-8601date string!

To see what makes dates and durations differ, consider a similar question. I give you two points in 3D space by their coordinates in some base. The 2 points are then well defined and so is the length of the segment joining them. Now I ask you to compute that length expressed in the input format, that is in 3D coordinates and ... you tell Houston you have a problem. Theses formats differ by nature and properties, you can't apply the input format to the output. You have to express the fact that the output is a period, that is prepend 'P' to the output format. See https://en.wikipedia.org/wiki/ISO_8601#Durations

Add to this fundamental problem the variability of a month (is that 28, 29, 30 or 31 days?) and of a year (is that 365 or 366 days?): this output date format looses its meaning and, if using the period format, it looses precision. Periods beyond days, hours and seconds are approximate at best.

The ISO-8601date format is very practical, thanks to its human-readability, un-ambiguousness and self-collating property. It's not even a 6D vector (Y, M, D, h, m, s) since year, month and day are not independant coordinates. But it can't express durations or time periods in the general case unless you use the 'P' format and accept its fuzzy meaning.

Things would be different if your input was in Julian date format: a Julian date is a real >= 0.0 and is in fact a Julian period from the start of the conventional Julian calendar. The difference between two Julian dates is then also a period, hence expressable in Julian date format. See AutoIt _DateToDayValue() and _DayValueToDate() functions albeit they don't handle fractional days (hms are unfortunately ignored).

[Gianni]

If you want the difference between two dates expressed in years, months, days, hours, minutes and seconds, this little _ElapsedTime() function can be useful for you.
It returns an array with those results in its elements, that you can then format as you better like... (maybe it can be shorten a bit)
(something similar already diascussed here.... https://www.autoitscript.com/forum/topic/206014-autoit-calculates-date/?do=findComment&comment=1483698)

#include <Date.au3>

Local $Start = "2020/01/01 08:00:00" ; "1962/05/02" & " " & "00:00:00"  ; _NowTime(); start date
Local $Stop = "2021/09/05 15:58:00" ; _NowCalc() ; _NowCalcDate()  ; end date

Local $aElapsed = _ElapsedTime($Start, $Stop)

; MsgBox(0, "Elapsed Time", $aElapsed[0] & " years, " & $aElapsed[1] & " months, " & $aElapsed[2] & " days, " & $aElapsed[3] & " hours, " & $aElapsed[4] & " minutes, " & $aElapsed[5] & " seconds")
ConsoleWrite("Elapsed Time from " & $Start & " to " & $Stop & " : " & $aElapsed[0] & " years, " & $aElapsed[1] & " months, " & $aElapsed[2] & " days, " & $aElapsed[3] & " hours, " & $aElapsed[4] & " minutes, " & $aElapsed[5] & " seconds" & @CRLF)

; returns an array with the elapsed time between 2 dates expressed in years, months, days, hours, minutes, seconds
Func _ElapsedTime($sStartDate, $sEndDate)
    Local Enum $iYears, $iMonths, $iDays, $iHours, $iMinutes, $iSeconds
    Local $aResult[6] ;
    $aResult[$iYears] = _DateDiff('Y', $sStartDate, $sEndDate)
    $aResult[$iMonths] = _DateDiff('M', _DateAdd('Y', $aResult[$iYears], $sStartDate), $sEndDate)
    $aResult[$iDays] = _DateDiff('D', _DateAdd('M', $aResult[$iMonths], _DateAdd('Y', $aResult[$iYears], $sStartDate)), $sEndDate)

    $aResult[$iHours] = _DateDiff('h', _DateAdd('D', $aResult[$iDays], _DateAdd('M', $aResult[$iMonths], _DateAdd('Y', $aResult[$iYears], $sStartDate))), $sEndDate)
    $aResult[$iMinutes] = _DateDiff('n', _DateAdd('h', $aResult[$iHours], _DateAdd('D', $aResult[$iDays], _DateAdd('M', $aResult[$iMonths], _DateAdd('Y', $aResult[$iYears], $sStartDate)))), $sEndDate)
    $aResult[$iSeconds] = _DateDiff('s', _DateAdd('n', $aResult[$iMinutes], _DateAdd('h', $aResult[$iHours], _DateAdd('D', $aResult[$iDays], _DateAdd('M', $aResult[$iMonths], _DateAdd('Y', $aResult[$iYears], $sStartDate))))), $sEndDate)

    Return $aResult ; [0] years; [1] months; [2] days; [3] hours; [4] minutes; [5] seconds
EndFunc   ;==>_ElapsedTime

 

[JockoDundee]

16 hours ago, jchd said:

For instance, year 0000 doesn't exist which makes your output an invalid ISO-8601date string!

True, but except for the inclusion of the prefix “P” (and the infix “T”) the resulting string is very much the same as mLipok envisioned, if one uses the alternative formatting mentioned:

Quote

Alternatively, a format for duration based on combined date and time representations may be used by agreement between the communicating parties either in the basic format PYYYYMMDDThhmmss or in the extended format P[YYYY]-[MM]-[DD]T[hh]:[mm]:[ss]. For example, the first duration shown above would be "P0003-06-04T12:30:05". However, individual date and time values cannot exceed their moduli (e.g. a value of 13 for the month or 25 for the hour would not be permissible).

The points about the fuzziness of intervalics > days is well taken.  However, it would seem that such durations when used in time intervals, can lose their fuzz because of the inclusion of anchoring start or ending datetimes:

Quote

There are four ways to express a time interval:

1. Start and end, such as "2007-03-01T13:00:00Z/2008-05-11T15:30:00Z"
2. Start and duration, such as "2007-03-01T13:00:00Z/P1Y2M10DT2H30M"
3. Duration and end, such as "P1Y2M10DT2H30M/2008-05-11T15:30:00Z"
4. Duration only, such as "P1Y2M10DT2H30M", with additional context information

 

since the notion of 1 month, for instance, is well defined because of the absolute references.

[jchd]

4 hours ago, JockoDundee said:

True, but except for the inclusion of the prefix “P”

That's why I highlighted date string. Period string is OK, within limitations.

 

[mLipok]

On 9/10/2021 at 1:58 PM, jchd said:

See https://en.wikipedia.org/wiki/ISO_8601#Durations

If it comes to the ISO standard I prefer: 

Quote

Duration only, such as "P1Y2M10DT2H30M".

But for AutoIt processing I prefer to keep the date uniform with _Date*() functions .

I understand that date like:

 "0000/00/00 07:58:00"

do not meet the condition of _DateIsValid()

But IMHO if in a ListView, you want to display the duration of something, without giving a description, I mean only in numerical form, then such a format for presenting the duration seem most understandable to the average end user.


 

[jchd]

OK if you and your users can cope with what it means and also what it doesn't say. I'm with you in that I'd rather use the explicit P1Y2M10DT2H30M05S formatfor processing purpose. Human eyes + brains work differently!