[C++ BCB] bcb線程

class TMyThread : public TThread
{
private:
    TEdit *edt;
    DWORD n;

public:

    __fastcall TMyThread(TEdit *Edit)
            : TThread(false)
    {
        edt = Edit;
        n = Edit->Text.ToIntDef(0);
        edt->Tag = (int)this;
    };
    __fastcall ~TMyThread(void)
    {
        edt->Tag = 0;
    };

    void __fastcall Execute(void)
    {
        while (!this->Terminated)
        {
            Sleep(200);
            this->Synchronize(ShowData);
        }
    }

    void __fastcall ShowData(void)
    {
        if (edt != NULL)  edt->Text = IntToStr(n++);
    }
};

void __fastcall TForm1::FormCreate(TObject *Sender)
{
   Button1->OnClick = Button1Click;
   Button2->OnClick = Button1Click;
   Button3->OnClick = Button1Click;
   Button4->OnClick = Button1Click;
}

void __fastcall TForm1::Button1Click(TObject *Sender)
{
    if (Sender == Button1)    new TMyThread(Edit1 );
    else if (Sender == Button2) new TMyThread(Edit2);
    else if (Sender == Button3) delete (TMyThread *)Edit1->Tag;
    else if (Sender == Button4) delete (TMyThread *)Edit2->Tag;
}