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Re^2: How to increment a MAC Address?

by mda2 (Hermit)
on Jun 16, 2005 at 17:04 UTC ( #467354=note: print w/replies, xml ) Need Help??


in reply to Re: How to increment a MAC Address?
in thread How to increment a MAC Address?

To increment a MAC Address, you need to convert HEX to DEC, Add AND convert DEC to HEX...

I propose this code.

sub addmac { my ( $mac, $add ) = @_; $mac =~ s/://g; my $dec = hex($mac); $mac = sprintf("%012x", $dec+$add); return join(":", $mac =~ /(..)/g ); } my $mac = '00:00:00:00:00:f1'; foreach ( 1 .. 32 ) { $mac = addmac($mac,$_*4); print "$mac\n"; }
I think others improve are possible, but it do a task.
... 00:00:00:00:01:a5 00:00:00:00:01:cd 00:00:00:00:01:f9 00:00:00:00:02:29 00:00:00:00:02:5d ... 00:00:00:00:03:9d 00:00:00:00:03:e9 00:00:00:00:04:39 00:00:00:00:04:8d

--
Marco Antonio
Rio-PM

Replies are listed 'Best First'.
Re^3: How to increment a MAC Address?
by merlyn (Sage) on Jun 16, 2005 at 17:08 UTC
      I did this:
      # clear separators to obtain a hex string $mac =~ s/://g; # convert hex string into a dec number my $dec = hex($mac); # revert into a hex string $mac = sprintf("%012x", $dec+$add);

      I don't see error here. I think it's used by context...

      --
      Marco Antonio
      Rio-PM

        # convert hex string into a dec number my $dec = hex($mac); # revert into a hex string $mac = sprintf("%012x", $dec+$add);
        My argument is with the word "dec" there. It's not decimal. It's just a number. In fact, it's more binary than it is decimal. {grin}

        The "hex" operator interprets a hex string or an octal string, converting them to a number. A number is an abstraction, without a numeric base, until it gets converted to a string again.

        Thus, you never really have a "decimal" number there. Just a number. Because you never printed it out.

        -- Randal L. Schwartz, Perl hacker
        Be sure to read my standard disclaimer if this is a reply.

Re^3: How to increment a MAC Address?
by ikegami (Pope) on Jun 17, 2005 at 23:13 UTC

    Close, but not quite. You're trying to store a 48bit number into a 32bit variable. (Well, it's 32 bit on my Windows machine.) You have an overflow problem.

    my $dec = hex('FF0000000000'); printf("%012x", $dec); __END__ Integer overflow in hexadecimal number at !.pl line 1 0000ffffffff

    You could use Math::BigInt, or you could use floating point numbers (doubles) as I've previously detailed.

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