see this thread:
http://free-pascal-lazarus.989080.n3.nabble.com/Lazarus-DateDif-function-needed-tt4034182.html#none
Is a function similiar to Jedi's DateDiff part of Freepascal now?
As i remember Michael van Canneyt wanted to implement that to Pascal 3.0??
That's Jedi's version:
procedure DateDiff(Date1, Date2: TDateTime; var Days, Months, Years: word);
var
DtSwap: TDateTime;
Day1, Day2, Month1, Month2, Year1, Year2: word;
begin
if Date1 > Date2 then
begin
DtSwap := Date1;
Date1 := Date2;
Date2 := DtSwap;
end;
DecodeDate(Date1, Year1, Month1, Day1);
DecodeDate(Date2, Year2, Month2, Day2);
Years := Year2 - Year1;
Months := 0;
Days := 0;
if Month2 < Month1 then
begin
Inc(Months, 12);
Dec(Years);
end;
Inc(Months, Month2 - Month1);
if Day2 < Day1 then
begin
// von mir auskommentiert Inc(Days, DaysPerMonth(Year1, Month1));
Inc(Days, DaysInAMonth(Year1, Month1));
if Months = 0 then
begin
Dec(Years);
Months := 11;
end
else
Dec(Months);
end;
Inc(Days, Day2 - Day1);
end;