Date: Thu, 8 Aug 2013 01:27:10 -0700 From: Peter Wemm <peter@wemm.org> To: s m <sam.gh1986@gmail.com> Cc: FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: how calculate the number of ip addresses in a range? Message-ID: <CAGE5yCoBYS2%2BsHoQXZvWMNPTQeEEtDX7LAKSBHJAZ4_rA2-byQ@mail.gmail.com> In-Reply-To: <CAA_1SgEEeyCOk%2Bi9Zp725RfQ9s0tpELXL0SSBeiN%2B60z%2BxqYUg@mail.gmail.com> References: <CAA_1SgEEeyCOk%2Bi9Zp725RfQ9s0tpELXL0SSBeiN%2B60z%2BxqYUg@mail.gmail.com>
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On Thu, Aug 8, 2013 at 12:04 AM, s m <sam.gh1986@gmail.com> wrote:
> hello guys,
>
> i have a question about ip addresses. i know my question is not related to
> freebsd but i googled a lot and found nothing useful and don't know where i
> should ask my question.
>
> i want to know how can i calculate the number of ip addresses in a range?
> for example if i have 192.0.0.1 192.100.255.254 with mask 8, how many ip
> addresses are available in this range? is there any formula to calculate
> the number of ip addresses for any range?
>
> i'm confusing about it. please help me to clear my mind.
> thanks in advance,
My immediate reaction is.. is this a homework / classwork / assignment?
Anyway, you can think of it by converting your start and end addresses
to an integer. Over simplified:
$ cat homework.c
main()
{
int start = (192 << 24) | (0 << 16) | (0 << 8) | 1;
int end = (192 << 24) | (100 << 16) | (255 << 8) | 254;
printf("start %d end %d range %d\n", start, end, (end - start) + 1);
}
$ ./homework
start -1073741823 end -1067122690 range 6619134
The +1 is correcting for base zero. 192.0.0.1 - 192.0.0.2 is two
usable addresses.
I'm not sure what you want to do with the mask of 8.
You can also do it with ntohl(inet_addr("address")) as well and a
multitude of other ways.
--
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI6FJV
UTF-8: for when a ' just won\342\200\231t do.
<brueffer> ZFS must be the bacon of file systems. "everything's better with ZFS"
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