Sorry, my previous reply was a bit of a quickie. I did some experiments and wanted to now more explicitly fill in some of the bits that you and I hinted at.

Your original code and my modified version here: 

my @range= unpack "N*", pack "C*", split /[. ]+/, "@ARGV";

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both work for any list of valid IP addresses in dotted-decimal notation, even those above 128.0.0.0.

The problem comes when you try to do: 

$range[0]..$range[1]

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with such large numbers. That causes Perl to squawk: 
Range iterator outside integer range at ...

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Which was news to me; thanks for teaching me something. (:

Your solution of using 0..$range[1]-$range[0] is quite good. You could also do: 

for(  $_= $range[0];  $_ <= $range[1];  $_++  )

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Both should work for even 56-bit integers (I don't recall IPv6 address notation...). Though, you can't use the "N" format for pack()/unpack() for more than 32 bits, so you'd need to build up the number: 
sub octets2num {
    my $val= 0;
    for(  split /\./, shift(@_)  ) {
        $val= 0x100*$val + $_;
    }
    return $val;
}
sub num2octects {
    my $val= shift(@_);
    my @bytes;
    while(  0 < $val  ) {
        unshift @bytes, $val%0x100;
        $val= int( $val / 0x100 );
    }
    return ! @bytes ? "0" : join ".", @bytes
}

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Note that using bit-wise operators (or use integer) above would break these. (I think using push instead of unshift and adding a reverse might be slightly more efficient.)

Update: I couldn't help golfing the first line of code a bit.

        - tye (just playing; that's how I usually learn)

In reply to (tye)Re2: BigInt usage by tye
in thread BigInt usage by ryan

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