Title: Get age from date of birth
You can solve this problem by comparing number of month with number of current month and comparing number of day with number of current day, if on the first step was equal.
procedure TForm1.Button1Click(Sender: TObject);
var
NowYear, NowMonth, NowDay: Word;
Year, Month, Day: Word;
YearsOld: Word;
begin
if Edit1.Text<>'' then
begin
DecodeDate(Now, NowYear, NowMonth, NowDay);
DecodeDate(StrToDateTime(Edit1.Text), Year, Month, Day);
if NowMonth>Month then
YearsOld:=NowYear-Year;
if NowMonth<Month then
YearsOld:=NowYear-Year-1;
if NowMonth=Month then
begin
if NowDay>=Day then
YearsOld:=NowYear-Year;
if NowDay<=Day then
YearsOld:=NowYear-Year-1;
end;
Label2.Caption:=IntToStr(YearsOld)+' years old';
end;
end;