Re: [libreoffice-users] Re: converting txt to dates

Am 2015-03-24 18:22, Andreas Säger schrieb:
> Am 24.03.2015 um 14:22 schrieb Kaj:
> > Hi !
> >
> > Now you happened to use the wrong conversion function, VALUE instead of
> > DATEVALUE, so of course it did not work. But even with the correct
> > function there seems to be some issues. According to the help text for
> > the date acceptance pattern: besides local ways to write date, also the
> > ISO standard is supported. This standard says that dates are written,
> > like all numbers in the decimal system, with most significant values to
> > the left and least significant figures to the right. Hence dates are
> > written "YYYY-MM-DD". I tested this in my computer and it worked very
> > well. Conversely I had no success with the format DD/MM/YYYY despite I
> > had introduced this as a pattern.
> >
> > I also tested some string manipulation to convert the string like this
> > =DATEVALUE(CONCATENATE(RIGHT(A1,4),"-",MID(A1,4,2),"-",LEFT(A,2)))
> and so does =VALUE(CONCATENATE(RIGHT(A1,4),"-",MID(A1,4,2),"-",LEFT(A,2)))
>
> > and that worked fine too. However this is much the same as using the
> > DATE function, proposed earlier by you Andreas:
> >      =DATE(RIGHT(A1,4),MID(A1,4,2),LEFT(A1,2))
> >
> > BUT! wrong! The DATE function converts numbers into a date value, so you
> > have to convert the strings into numbers. Thus:
> >      =DATE(VALUE(RIGHT(A4,4)),VALUE(MID(A4,4,2)),VALUE(LEFT(A4,2)))
> Wrong. The DATE function calculates one integer day number from 3
> numbers year, month and day.
> Without VALUE(), =DATE(RIGHT(A4,4),MID(A4,4,2),LEFT(A4,2)) works as well
> because Calc implicitly converts integer numerals (strings consisting of
> digits only).
Not wrong, but possibly not fully exhaustive. Did I mention how many 
numbers that were input for the conversion? If my eyes are still working 
as expected I read the word "numbers" (plural) when describing the main 
procedure. Well, in one aspect I have to admit I was not fully informed. 
I was not aware of the implicit conversion of strings containing numbers 
into numbers. Good to know. However, despite this, I prefer to define 
this conversion explicitly to have full control and not being surprised 
at some possible change in the future.
> There are no "date values" in spreadsheets. 0 formatted as date gives
> 1899-12-30, 36526 formatted as date gives 2000-01-01. Both values, the
> "date value" and the integer are the exact same value displayed in
> different number formats like you can display them in different fonts,
> colors or sizes.
Well, you call them date numbers, and that is ok for me. But as they are 
not just any, but defined as the number of days passed after 1899-12-30, 
I cannot see anything wrong in calling them date value. And moreover 
they are not simple integers, since the time of day is included as a 
decimal part, just the way you describe in the next paragraph. Did you 
think I do not know that?
> If the value is an integer day number without time, VALUE and DATEVALUE
> return the exact same day number.
>
> In English notation with point as decimal separator and comma as list
> separator:
> =VALUE("2000-1-1 12:00") => 36526.5 (full day number with time)
> =DATEVALUE("2000-1-1 12:00") <=> INT(VALUE("2000-1-1 12:00")) => 36526
> (integer day number only cutting of the time fraction of the day)
> TIMEVALUE("3.14159") <=> MOD(VALUE("3.14159"),1) => 0.5 (the fraction of
> the day cutting off the integer day number).
>
>
> All this conversion from strings to numbers is unrelated to the date
> acceptance patterns that determines how Calc turns your keyboard input
> into day numbers.


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