Kreditcard Generator

function next10(i:integer):integer;
begin
  repeat
    inc(i);
  until i mod 10=0;
  result:=i;
end;

function process(s:String):string;
var
    i, x, y, z : integer;
    s10:string;
begin
  result:='';
  x := 0;
  y := 0;
  z := 0;

  for i:=1 to length(s) do begin
    if i mod 2 <> 0 then begin
    x:=strtoint(s[i])*2;
      if x>=10 then x:=x-9;
      inc(y,x);
      end
      else
    inc(y,strtoint(s[i]));
  end;

  z:=next10(y);
  result:=s+inttostr(z-y);
end;

function getrandom9(d:integer):string;
var
    i : integer;
begin
  randomize;
  result:='';
  for i:=1 to 9+d
    do
    result:=result+inttostr(random(10));
end;

Beispiel :

procedure TForm1.Button1Click(Sender: TObject);
var
    ccdum, banks, gen : string;
begin
  if pos('|',bank.text) > 0 then
  banks:=trim(copy(bank.Text,1,pos('|',bank.Text)-1))
  else
  banks:=bank.Text;
  ccdum:=banks+getrandom9(6-length(banks));
 gen:=process(ccdum);

  if length(gen)=16 then
  begin
    case gen[1] of
    '5': Gen := 'Master Card: ' + gen;
    '4': Gen := 'Visa: ' + gen;
    '3': Gen := 'American Express: ' + gen;
    else
    Gen:='Unknown: ' + gen;
  end;
  Memo1.Lines.Add(gen);
  end
  else
  button1click(nil);
end;