Отладка программы с исключениями

unit Unit2;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
 
type
  TForm2 = class(TForm)
 
    Edit1: TEdit;
    Edit2: TEdit;
    ComboBox1: TComboBox;
    Button1: TButton;
    Button2: TButton;
    ScrollBar1: TScrollBar;
    Memo1: TMemo;
 
    procedure Button2Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Memo1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form2: TForm2;
num:integer;
stroka:string;
k:byte;
i:byte;
implementation
 
uses Unit1;
 
{$R *.dfm}
procedure TForm2.Button2Click(Sender: TObject);
begin
Form2.Close;
end;
 
procedure TForm2.Button1Click(Sender: TObject);
begin
k:=0;
for i:=0 to ComponentCount-1 do
if (Components[i] is TEdit)and((Components[i] as TEdit).Text='')then k:=1;
if k=1 then
 begin
  ShowMessage('Íå âñå ïîëÿ Edit çàïîëíåíû');
  exit
  end;
try
  case ComboBox1.ItemIndex of
0:Memo1.Lines.Add(Edit1.Text + '+' + Edit2.Text + '=' + FloatToStr(StrToFloat(Edit1.Text) + StrToFloat(Edit2.Text)));
1:Memo1.Lines.Add(Edit1.Text + '-' + Edit2.Text + '=' + FloatToStr(StrToFloat(Edit1.Text) - StrToFloat(Edit2.Text)));
2:Memo1.Lines.Add(Edit1.Text + '*' + Edit2.Text + '=' + FloatToStr(StrToFloat(Edit1.Text) * StrToFloat(Edit2.Text)));
3:Memo1.Lines.Add(Edit1.Text + '/' + Edit2.Text + '=' + FloatToStr(StrToFloat(Edit1.Text) / StrToFloat(Edit2.Text)));
end;
num:=StrToInt(Stroka);
 
except
 on EDivByZero do MessageDlg ('dgsag', mtWarning,[mbOk],0);
 on EConvertError do ShowMessage ('îøèáêè ïðåîáðàçîâàíèå ñòðîêè â öåëîå ÷èñëî');
 end;
end;
procedure TForm2.Memo1Change(Sender: TObject);
begin
 
end;
 
end.