Re: [Lazarus] DateDif function needed

[John Landmesser]

On 12.11.2013 21:01, waldo kitty wrote:

type
  Date_Diff = record
                Years,
                Months,
                Days: Word;
              end;

function CalendarDateDiff(Date1,Date2: TDateTime): Date_Diff;
var
  theDiffRec: Date_Diff;
  Cmp: Integer;
  loDate,hiDate: TDateTime;
  loYear,hiYear,loMonth,hiMonth,loDay,hiDay: Word;
begin
  FillChar(theDiffRec,SizeOf(theDiffRec),0);  // init results to zero
  Cmp:=CompareDateTime(Date1,Date2);          // compare dates
  If Cmp<0 then
  begin
    loDate:= Date1;                           // and set loDate to oldest
    hiDate:= Date2;
  end
  else if Cmp>0 then
  begin
    loDate:= Date2;                           // and set loDate to oldest
    hiDate:= Date1;
  end;
  DecodeDate(loDate,loYear,loMonth,loDay);
  DecodeDate(hiDate,hiYear,hiMonth,hiDay);
  theDiffRec.Years:= hiYear - loYear;

if (loMonth > hiMonth) or ((loMonth = hiMonth) and (loDay > hiDay)) then

  begin
    theDiffRec.Years:= theDiffRec.Years - 1;
  end;
  if loMonth > hiMonth then
  begin
    hiMonth:= hiMonth + 12;
  end;
  theDiffRec.Months:= hiMonth - loMonth;
  if hiDay >= loDay then
  begin
    theDiffRec.Days:= hiDay - loDay
  end
  else
  begin
    if theDiffRec.Months = 0 then
    begin
      theDiffRec.Months:= 11;
    end
    else
    begin
      theDiffRec.Months:= theDiffRec.Months - 1;
    end;
    theDiffRec.Days:= DaysInAMonth(hiYear,loMonth) - loDay + hiDay;
  end;
  Result:= theDiffRec;

end;

Which is correct?

Date1 := 29.2.2000
Date2 := 28.02.2001

Your function:
0 Y, 11 M, 27 D

Rxlib ( Jedi ) DateDiff:
0 Y, 11 M, 28 D

Libre Office Calc:
0 Y, 11 M, 30 D

The table - function of Libre Office Calc is called in german DATUMDIF()

Get a calendar and count??





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