On 31 Oct 2009, at 16:03, B Maqueira wrote:
I need to sort eficiently a large array (~9000) of SNMP OIDs.I am currently trying the following code: my @sorted_oids = map { $_->[0] } sort { $a->[1] cmp $b->[1] } map { [$_, pack('w*', split(/\./, $_))] } @oids; But this fails since it outputs 1.3.6.1.4.1.2333.3.2.61001.1.10 before than 1.3.6.1.4.1.2333.3.2.8080.1.1.1 Any ideas?
That's because "w" format is a BER encoding, and this does not map integers into strings such that ordering is maintained. For example, 16383 encodes to "\xff\x7f", but 16384 encodes to "\x81\x80\x00" which string-sorts earlier.
Relatively few encodings *do* maintain that ordering. Big-endian fixed- width does. So I'd use "N*" instead in your pack format, mainly because I'm not entirely sure whether the components of SNMP OIDs can ever be greater than 65535 and thus whether I could thus get away with "n*" to halve the storage required.
