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Re^3: Create Arrays On-the-Fly

by fullermd (Priest)
on Aug 27, 2009 at 04:37 UTC ( #791521=note: print w/replies, xml ) Need Help??

in reply to Re^2: Create Arrays On-the-Fly
in thread Create Arrays On-the-Fly

Right, but you don't have to presize it. Just push entries onto it as you parse them.

For instance, to invent a stupid-simple data format, and demonstrate parsing it and doing a thing or two with the data once parsed:

#!/usr/bin/env perl5 use strict; use warnings; my @clients; my %tmp; while(<DATA>) { chomp; # Assume a format of "Type Data" my ($type, $data) = split / /; # If it's a MAC address, save off our pre-existing record (if any) +, # and start a new one. if($type eq "MAC") { if(keys %tmp) { # Have to unroll a copy here, otherwise the next line empt +ies # it out. push @clients, { (%tmp) }; %tmp = (); } $tmp{MAC} = $data; } # RSSI and SNR just get saved $tmp{RSSI} = $data if $type eq "RSSI"; $tmp{SNR} = $data if $type eq "SNR"; } # Save the 'last' one if we fell off the end push @clients, \%tmp if keys %tmp; # Show it use Data::Dumper; print Dumper \@clients; # Find a given entry sub showmacsnr { my $mac = shift; my @ba = grep { $_->{MAC} eq $mac } @clients; if(@ba) { my $ent = $ba[0]; print "MAC $mac has SNR $ent->{SNR}\n"; } else { print "Can't find MAC $mac\n"; } } showmacsnr("ba:98:76:54:32:10"); showmacsnr("thi:is:is:nt:re:al"); # Sample data __DATA__ MAC 01:23:45:67:89:ab RSSI 12 SNR 18 MAC ba:98:76:54:32:10 RSSI 7 SNR 3

So you end up with output like:

% ./ $VAR1 = [ { 'RSSI' => '12', 'SNR' => '18', 'MAC' => '01:23:45:67:89:ab' }, { 'SNR' => '3', 'RSSI' => '7', 'MAC' => 'ba:98:76:54:32:10' } ]; MAC ba:98:76:54:32:10 has SNR 3 Can't find MAC thi:is:is:nt:re:al

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