Re^2: behavior of bitwise shift

just a quic hack how subnets can be translated without using a module

my $cidr = 8;
my $mask = "1" x ( 32 - $cidr ) . "0" x $cidr;
print $mask, "\n";
$mask = join ".", ( unpack "C4", ( pack "B*", $mask ) );
print $mask, "\n"
[download]

i also suggest Net::Subnets for working with subnets if it does what you want, in particular matching ip's against subnets is very fast.

Comment on Re^2: behavior of bitwise shift Download Code

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Re^3: behavior of bitwise shift by Golo (Friar) on Oct 25, 2004 at 15:11 UTC
I think you'll need to change `my $mask = "1" x ( 32 - $cidr ) . "0" x $cidr;` [download] to `my $mask = "1" x $cidr . "0" x ( 32 - $cidr );` [download] since /8 means a mask of 255.0.0.0 and not 255.255.255.0 which is /24. But thanks a lot for this example - I was wondering how do that without a module (and could not figure how bitwise shifting should help).	[reply] [d/l] [select]
Re^4: behavior of bitwise shift by Taulmarill (Deacon) on Oct 25, 2004 at 15:17 UTC
oh, yes, you are abviously right. i was so preoccupied remembering what pack/unpack modes i have to use that i just missed that.	[reply]