BOOL GetSerialNo(HWND hDlg)
{
	int i;
	TCHAR szUserName[16];
	GetDlgItemText(hDlg, IDC_USERNAME, szUserName, 16);

	if(_tcslen(szUserName) == 0)
		return FALSE;

	g_UserVal = GetUserValue(szUserName);
	memset(g_UserBits, 0, sizeof(g_UserBits));
	InitUserBits();

	g_Top = 0;

	for(i = 9; i >= 1; i--)
		SetBit(i, 0);

	//字符串的 null-terminator;
	g_SerialNo[g_Top] = 0;
	++g_Top;

	SetDlgItemText(hDlg, IDC_SERIALNO, g_SerialNo);
}