procedure TfrmMain.FormCreate(Sender: TObject);
begin
AList := TStringList.Create;
end;
procedure TfrmMain.FormDestroy(Sender: TObject);
begin
AList := nil;
end;
procedure TfrmMain.Button1Click(Sender: TObject);
var
s1, s2, s3: string;
i: Integer;
begin
s1 := '123';
s2 := '23456';
s3 := '654870';
Decode(s1);
Decode(s2);
Decode(s3);
for i := 0 to AList.Count -1 do
ListBox1.Items.Add(AList[i]);
end;
procedure TfrmMain.Decode(const s: string);
var
i, Idx: Integer;
begin
for i := 1 to Length(s) do
begin
Idx := AList.IndexOf(s[i]);
if Idx = -1 then
AList.Add(s[i]);
end;
end;