japhy's code is certainly very quick,
Benchmarking about
43% better than anything I could come up with on short notice.
The 'radix_sort' is obviously more efficient for this kind of
application than the built in sort of Perl.
However, under Perl 5.6 + strict + '-w', the following change
is required to avoid compilation errors:
sub IPsort {
map inet_ntoa($_),
IP_radix_sort
map inet_aton($_),
@_;
}
The alternative code which
Benchmarks in at #2, but has
the advantage of simplicity:
sub byip { inet_ntoa($a) cmp inet_ntoa($b) }
foreach (sort byip @ip_list) ...
BTW, I tested both with 100_000 random IP addresses by 10
runs (approx 86 to 150s per test).