snmp++中的snmpGet例子，在ipv4下运行可以，ipv6下出错

/*_############################################################################
  _##
  _##  snmpGet.cpp 
  _##
  _##  SNMP++v3.2.24
  _##  -----------------------------------------------
  _##  Copyright (c) 2001-2009 Jochen Katz, Frank Fock
  _##
  _##  This software is based on SNMP++2.6 from Hewlett Packard:
  _## 
  _##    Copyright (c) 1996
  _##    Hewlett-Packard Company
  _## 
  _##  ATTENTION: USE OF THIS SOFTWARE IS SUBJECT TO THE FOLLOWING TERMS.
  _##  Permission to use, copy, modify, distribute and/or sell this software
  _##  and/or its documentation is hereby granted without fee. User agrees
  _##  to display the above copyright notice and this license notice in all
  _##  copies of the software and any documentation of the software. User
  _##  agrees to assume all liability for the use of the software;
  _##  Hewlett-Packard and Jochen Katz make no representations about the
  _##  suitability of this software for any purpose. It is provided
  _##  "AS-IS" without warranty of any kind, either express or implied. User
  _##  hereby grants a royalty-free license to any and all derivatives based
  _##  upon this software code base.
  _## 
  _##  Stuttgart, Germany, Fri May 29 22:35:14 CEST 2009
  _## 
  _##########################################################################*/
/*
  snmpGet.cpp

  Copyright (c) 1996
  Hewlett-Packard Company

  ATTENTION: USE OF THIS SOFTWARE IS SUBJECT TO THE FOLLOWING TERMS.
  Permission to use, copy, modify, distribute and/or sell this software
  and/or its documentation is hereby granted without fee. User agrees
  to display the above copyright notice and this license notice in all
  copies of the software and any documentation of the software. User
  agrees to assume all liability for the use of the software; Hewlett-Packard
  makes no representations about the suitability of this software for any
  purpose. It is provided "AS-IS" without warranty of any kind,either express
  or implied. User hereby grants a royalty-free license to any and all
  derivatives based upon this software code base.

  Peter E. Mellquist
*/
char snmpget_cpp_version[]="@(#) SNMP++ $Id: snmpGet.cpp 1534 2009-05-27 22:07:17Z katz $";

#include "snmp_pp/snmp_pp.h"
#include <stdlib.h>
#include <stdio.h>
#define  strcasecmp stricmp

#ifdef SNMP_PP_NAMESPACE
using namespace Snmp_pp;
#endif

#if (__GNUC__ > 2)
#include <iostream>
using std::cerr;
using std::cout;
using std::endl;
using std::flush;
#else
#include <iostream.h>
#endif

int main(int argc, char **argv)
{
   //---------[ check the arg count ]----------------------------------------
   if ( argc < 2) {
   cout << "Usage:/n";
   cout << argv[0] << " IpAddress | DNSName [Oid] [options]/n";
   cout << "Oid: sysDescr object is default/n";
   cout << "options: -vN , use SNMP version 1, 2 or 3, default is 1/n";
   cout << "         -PPort , remote port to use/n";
   cout << "         -CCommunity_name, specify community default is 'public' /n";
   cout << "         -rN , retries default is N = 1 retry/n";
   cout << "         -tN , timeout in hundredths of seconds; default is N = 100/n";
#ifdef _SNMPv3
          cout << "         -snSecurityName, " << endl;
          cout << "         -slN , securityLevel to use, default N = 3 = authPriv" << endl;
          cout << "         -smN , securityModel to use, only default N = 3 = USM possible/n";
          cout << "         -cnContextName, default empty string" << endl;
    &nb