Tryin to call a function

Hello,

I have a quick question....  As it is academically related, I am not after answers, just a push in the right direction.  I am studying in isolation though, so any advise would be greatly appreciated!!

Basically, I am trying to do the palindrome thing, and I'm 1/2 way there. I have cleaned the string (removed all non alpha numeric and changed to lowercase), now I am trying to call: procedure reverse(const: string; var T: string);
Which is where I am running into problems.

Here is my code so far:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Variants, Graphics, Controls, Forms,
Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    edtInput: TEdit;
    Palindromes: TMemo;
    SaveDialog1: TSaveDialog;
    Test: TButton;
    procedure TestClick(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  edtInput: TEdit;
  Palindromes: TMemo;

const
  Chars : Set of Char = ['a'..'z','A'..'Z','0'..'9'];

implementation

{$R *.DFM}

function clean(const S: string): string;
var count: Integer;
begin

for count := 0 To Length(s) do
if S[count] in Chars
  then result := result + S[count];

end;

procedure reverse(const S: string; var T: string);

begin
writeln(test);
// yet to write this part
end;

procedure TForm1.TestClick(Sender: TObject);
var result, input : string;

begin

if length(edtInput.Text) = 0 then
showMessage('Please enter text')
else
input := clean(edtInput.Text);
result := lowercase(s);
showmessage(clean(input));

{ tried top call the procedure here as in: input := reverse(edtInput); but it did not work. I am guessing that I am not passing enough parameters somehow, as in it expecting two strings? }

end;

end.
 

Many thanks.