判断内外网环境

#include "stdafx.h"
#include "windows.h"
#include <Sensapi.h>
#include <iostream>
#include <Wininet.h>

#pragma comment(lib, "Sensapi.lib")
#pragma comment(lib, "Wininet.lib")
using namespace std;

int _tmain()
{
	do
	{
		//IsNetworkAlive
		DWORD dw;
		BOOL isConnect = ::IsNetworkAlive( &dw );
		if(isConnect)
			cout << "IsNetworkAlive连接" <<endl;
		else
			cout << "IsNetworkAlive未连接" <<endl;

		//InternetGetConnectedState
		DWORD dw2;
		BOOL ret = InternetGetConnectedState(&dw2, 0);
		if (ret)
			cout << "InternetGetConnectedState连接" <<endl;
		else
			cout << "InternetGetConnectedState未连接" <<endl;

		//InternetCheckConnection
		BOOL bConnected = InternetCheckConnection(_T("http://www.baidu.com"), FLAG_ICC_FORCE_CONNECTION, 0);
		if (bConnected)
			cout << "InternetCheckConnection连接" <<endl;
		else
			cout << "InternetCheckConnection未连接" <<endl;

		//IsDestinationReachable(_T("http://www.google.com"), )
	} while (FALSE);

	getchar();
	return 1;
}

原文地址：https://www.cnblogs.com/P201521440004/p/10894105.html