Is there a way to check if there is network connectivity in a C/C++ program?

Yes. There are many ways for you to check activity, in variety of situations and operatings systems. You can check for wifi activity, bluetooth activity, serial activity, ethernet activity, even 1394 activity. You can even test what sites the person has visited or hasn't visited, like www.google.com for instance. You can do anything with C++


With C++, you can.

And of course, you can do it too in C.

Yes, googling was the first thing I tried but didn't find anything for linux. Could you more specific?

I believe you are the one needing to be more specific.

What kind of connectivity test are you looking for ?

Ok, argument accepted. What I want to do is to change the ftp client code to do the following (assuming I would like to download a file from a wireless node):

1) Check if there is connectivity with that node
2) Well if there isn't sleep for let's say 10ms and check again

Simply a while(!not_connected()) { sleep(some_time); }

What I just thought now is that I could send a ftp start session command and check if the send() func of the TCP conn fails. This is the specific part.

More generally, in win programming there is a GetInternetConnectivity() func that returns true if the computer is connected the internet. Is there some same functionality in linux (syscall?) or a workaround that does tha same. jilliagre thanks for your interest.