BOOL CLiftCtrlModbusConfigDlg::CheckValid(const CString &str){ ASSERT(str.GetLength() > 0); if ((str[0] == '-' && str[1] > '0' && str[1] <= '9')|| (str[0] > '0' && str[0] <= '9' && str.GetLength() >= 1) || (str[0] == '0' && str.GetLength() == 1)) {  for (int i = 1; i < str.GetLength(); i++)  {   if(!isdigit(str[i]))   {    return FALSE;   }  }  return TRUE; } return FALSE;}