I'll not look this up now, but I'm pretty sure that the answer is found in inlet_aton() in the c-library ping has been linked against, not ping.

I think you meant inet_aton() or inet_addr().

However, the value of looking at ping is it let's you see a simple example of a lot of networking system calls which you can then dig into. I had a class project to write a simple web-server and text based browser in C and ping was actually a great place to start.