Programmatically check whether my machine has internet access or not

Question

How can I programmatically check whether my machine has internet access or not using C/C++, is it just a matter of pinging an IP? How does NIC do it ? I mean something like

Answer 1

There is nothing of that sort I think, but you can try this:

The easiest way is to try to connect to a known outside IP address.

If it fails in Windows, the connect function will return SOCKET_ERROR, and WSAGetLastError will usually return WSAEHOSTUNREACH (meaning the packet couldn't be sent to the host).

In Linux, you'll get back a -1, and errno will be ENETUNREACH. Some useful links:

1. Link for Windows Sockets

2. Link for Linux/Unix sockets