perl实例之IP地址到主机名的转换

#!/usr/bin/perl

use Socket;
my $ADDR_PAT = /^d+.d+.d+.d+$/;

while (<>) {
  chomp;
  die "$_: Not a valid address" unless /$ADDR_PAT/o;
  my $name = gethostbyaddr(inet_aton($_),AF_INET);
  $name ||= '?';
  print "$_ => $namen";
}

#!/usr/bin/perl
use Socket;

my $packed_address = gethostbyname("localhost");
unless ($packed_address) {
    print "$_ => ?n";
    next;
}
my $dotted_quad    = inet_ntoa($packed_address);
print "$_ => $dotted_quadn";