Как объявить созданную функцию, чтобы ей пользоваться?

void __fastcall TForm1::test(TObject *Sender)
{}

void __fastcall TForm1::test(TObject *Sender);

&test;

class TForm1 : public TForm
{
__published:    // IDE-managed Components
    TButton *Button1;
    TLabel *Label1;
    TButton *Button2;
    TButton *Button3;
    TTimer *Timer1;
    void __fastcall Button1Click(TObject *Sender);
    void __fastcall Button2Click(TObject *Sender);
    void __fastcall Timer1Timer(TObject *Sender);
    void __fastcall Button3Click(TObject *Sender);
private:    // User declarations
public:     // User declarations
    __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif
......
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
 
int test(int a)
{
 return a;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
 Label1->Caption=StrToInt(test(StrToInt(Label1->Caption)+1));
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender)
{
 Timer1->Enabled=true;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
 Label1->Caption=StrToInt(test(StrToInt(Label1->Caption)+1));
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::Button3Click(TObject *Sender)
{
Timer1->Enabled=false;
}

void f(int a) { тело }