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Comment by digitalsushi | Hacker News Reader

I believe you can also represent an ipv4 address in base 10, by doing something like

a.b.c.d, (a * 2^24) + (b * 2^16) + (c * 2^8) + (d * 2^0)

(the first time i did this was the first time I understood raising a constant to zero was one, so I left it there for myself)

The resultant number should be somewhere between 0 and (2^32)-1. It's a neat toy. I'm not sure what value it has in practice.

192 x 2^24 + 168 x 2^16 + 0 x 2^8 + 1 x 2^0 == 3232235521

ping 3232235521 PING 3232235521 (192.168.0.1): 56 data bytes Request timeout for icmp_seq 0 ^C

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I've used this a handful of times, actually!

I've mostly done it to determine a "next" IP address from a large range - i.e, what IP comes after 10.0.0.255, and how can I bound it between 10.0.0.30 and 10.0.1.128?

It's much easier to increment an integer, compare it to other integers, and then convert it back to an string-format IP than it is to implement those operations by "parsing" IP addresses.

An IP address like 127.0.0.1 is an integer, written in an odd base 256 notation! What I think you mean is that it's easier to increment an integer written in conventional base 10, because people are used to working with numbers like that.

I'm imagining magmastonealex found it useful for things like working with each of 10.0.0.0/16 without having to manage the digits of those base-256 numbers:

  for (var i = 0; i < 2 ** 16; i++) {
    work("10.0." + i);
  }

as opposed to

  for (var i = 0; i < 2 ** 16; i++) {
    work("10.0." + i / 256 + "." + i % 256);
  }

This is neat!

Here's a JS version:

  > const ip2dec = ip => ip.split(".").reverse().reduce((acc, n, i) => acc + (parseInt(n) * (2 ** (i * 8))), 0)
  > ip2dec("192.168.0.1")
  3232235521
  > ip2dec("192.168.1.1")
  3232235777
  > ip2dec("0xDE.0xAD.0xBE.0xEF")
  3735928559

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