> I read that gethostbyname2 and gethostbyaddr for IPv6 is being
> deprecated and that I should use getaddrinfo or getnodebyname
> instead.  And inet_aton manual recommends getaddrinfo and getnameinfo
> for IPv6.

> But how can I get gethostbyname2 and gethostbyaddr to work for IPv6?

Why would you want to?  Why _not_ use getnameinfo and getaddrinfo?

> Here are some examples:

>  $ ./a.out -6 ::1
>  Hostname: ::1
>  Address: 0.0.0.0

Well, yes, the first four octets of ::1 are zero.  What's surprising
about this?

>  $ ./a.out -6 localhost
>  Hostname: localhost
>  Address: 0.0.0.0

> I wanted the above to return:
>  Hostname: localhost
>  Address: ::1

Then you need to print it out correctly.  The printf responsible for
that line reads

>             printf("Address: %u.%u.%u.%u\n",
>                     (0xff & h->h_addr_list[idx][0]),
>                     (0xff & h->h_addr_list[idx][1]),
>                     (0xff & h->h_addr_list[idx][2]),
>                     (0xff & h->h_addr_list[idx][3]) );

and I am not really able to comprehend any mindset that expects that to
_ever_ print "Address: ::1".

You are also using sockaddr_in and inet_aton, which are IPv4-only.
(I'm not sure about gethostbyaddr(), but I think it too may be
v4-only.)

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