Title: Validate a Credit Card
Question: Validate a Credit Card?
Answer:
//You need just a Button and an Edit Box
procedure TForm1.Button1Click(Sender: TObject);
var
i,digit,sum:integer;
begin
sum:=0;
for i:=16 downto 1 do begin
digit:=strtoint(edit1.Text[i]);
if digit mod 2=0 then
sum:=sum+digit else
sum:=sum+(digit*2);
end;
if sum mod 10=0 then
messagebox(0,'Credit card is valid','info',0) else
messagebox(0,'Credit card is NOT valid','info',0);
end;
{Next time, I will write complicated example..How to validate credit card by prefixes etc.}
//
// Have a fun
//