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Manipulating TDateTime

Posted on 2001-06-29
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Last Modified: 2010-04-06
Does anyone know of an easy way to add a certain number of days, months, or years to a TDateTime variable?

As in:

function AddDaysToTDate(temp_days : integer; temp_TDateTime : TDateTime) : TDateTime;

function AddMonthsToTDate(temp_months : integer; temp_TDateTime : TDateTime) : TDateTime;

function AddYearsToTDate(temp_years : integer; temp_TDateTime : TDateTime) : TDateTime;

You pass in the amount you want to increment by (days, months, or years) and the TDateTime you are modifying.  Function spits back the TDateTime value that reflects the increment.

Thank you,

Tom



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Comment
Question by:knowlton
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9 Comments
 
LVL 6

Expert Comment

by:edey
ID: 6238702
var
 dt : TDateTime;

add 1 day: dt := dt + 1;


GL
Mike
0
 
LVL 6

Expert Comment

by:edey
ID: 6238725
var
 dt : TDateTime;
 y,m,d : word;
begin
 dt := now;//today.currentTime;
 dt := dt + 1/24;//one hour from now;
 dt := dt+1;//tomorrow
 decodeDate(dt,y,m,d);
 dt := encodeDate(y,m+1,d-1);//one month from now ('cause dt _was_ tomorrow)
 dt := encodeDate(y+1,m,d-1);//one year from tomorrow;

GL
Mike
0
 
LVL 13

Accepted Solution

by:
Epsylon earned 50 total points
ID: 6238737
function AddDaysToTDate(temp_days : integer; temp_TDateTime : TDateTime) : TDateTime;
begin
  Result := temp_TDateTime + temp_days;
end;

function AddMonthsToTDate(temp_months : integer; temp_TDateTime : TDateTime) : TDateTime;
begin
  Result := IncMonth(temp_TDateTime, temp_months);
end;

function AddYearsToTDate(temp_years : integer; temp_TDateTime : TDateTime) : TDateTime;
begin
  Result := IncMonth(temp_TDateTime, temp_years * 12);
end;
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LVL 5

Author Comment

by:knowlton
ID: 6238761
Ahhh...


While you are correct, Mike, I think I will go with Epsylon on this one.

IncMonth is what I actually needed.

I did not know if such a function existed for TDateTime variables.  I was thinking I would have to calculate the number of days in a Month range:

5 months x approx 30 days per month := 150 days (except not all months have 30 days)

I am guessing IncMonth accounts for this?

Thanks Epsylon.
0
 
LVL 5

Author Comment

by:knowlton
ID: 6238767
Looking back, I guess adding days to a TDateTime was kind of a stupid question...ha ha.
0
 
LVL 5

Author Comment

by:knowlton
ID: 6238773
Thank you both!
0
 
LVL 13

Expert Comment

by:Epsylon
ID: 6238779
You can quickly test those functions with a TMonthCalendar and this code:

procedure TForm1.Button1Click(Sender: TObject);
begin
  MonthCalendar1.Date := AddDaysToTDate(1, MonthCalendar1.Date);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  MonthCalendar1.Date := AddMonthsToTDate(1, MonthCalendar1.Date);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  MonthCalendar1.Date := AddYearsToTDate(1, MonthCalendar1.Date);
end;
0
 
LVL 13

Expert Comment

by:Epsylon
ID: 6238782
Thank you for the points  :o)
0
 
LVL 5

Author Comment

by:knowlton
ID: 6238870
No problem.  I hope Mike is not too upset.  I guess it is really up to me who I give points to, but I still hate to step on toes...know what I mean?
0

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