String to Byte and Byte to String: Delphi

uFrmPrincipal;
interface
uses
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
    Dialogs, DateUtils, StdCtrls, Buttons, ExtCtrls;
type
  { Note the creation of two arrays }  
    TByteArr = array of byte;
    TStringArr = array of String;
 
    TFrmStringToByte = class(TForm)
        BitBtn2: TBitBtn;
        Memo1: TMemo;
        LabeledEdit1: TLabeledEdit;
        BitBtn1: TBitBtn;
        procedure BitBtn2Click(Sender: TObject);
        procedure BitBtn1Click(Sender: TObject);
    private
{ Note the two functions created for the conversion }  
        function StrToByte(const Value: String): TByteArr;
        function ByteToString(const Value: TByteArr): String;
        { Private declarations }
    public
    { Public declarations }
end;
 
var
FrmStringToByte: TFrmStringToByte;
 
implementation
{$R *.dfm}
 
function TFrmStringToByte.StrToByte(const Value: String): TByteArr;
var
    I: integer;
begin
    SetLength(Result, Length(Value));
    for I := 0 to Length(Value) - 1 do
        Result[I] := ord(Value[I + 1]) – 48;
end;
 
function TFrmStringToByte.ByteToString(const Value: TByteArr): String;
var
    I: integer;
    S : String;
    Letra: char;
begin
    S := '';
    for I := Length(Value)-1 Downto 0 do
    begin
        letra := Chr(Value[I] + 48);
        S := letra + S;
    end;
    Result := S;
end;
 
procedure TFrmStringToByte.BitBtn1Click(Sender: TObject);
Var
    ArByte : TByteArr;
    I : Integer;
begin
    SetLength(ArByte, Memo1.Lines.Count);
    for I := 0 to Memo1.Lines.Count - 1 do
        ArByte[I] := StrToInt(Memo1.Lines.Strings[I]);
    ShowMessage(ByteToString(ArByte));
end;
 
procedure TFrmStringToByte.BitBtn2Click(Sender: TObject);
Var
    xByte: TByteArr;
    I: integer;
begin
    Memo1.Clear;
    xByte := StrToByte(LabeledEdit1.Text);
    for I := 0 to Length(xByte) - 1 do
        Memo1.Lines.Add(IntToStr(xByte[I]));
end; 
end.