Looping through an Array using another Array without joining them

Question

What I'm trying to do is use an Array of names to loop through several different Arrays. Here's what I have

my @Sensor1 = ("1.2.3.4","1.2.3.5","1.2.3.6");
my @Sensor2 = ("2.2.2.1","2.2.2.2","2.2.2.3");
my @Sensor3 = ("128.0.0.1","128.0.0.2","128.0.0.3");
my @Names = ("Sensor1","Sensor2","Sensor3");
my ($Name, $IP);

foreach $Name (@Names){
  foreach $IP (@$Name){
    print "$Name"," $IP","\n";
  }
}

This causes it to error out because it is attempting to look for an array named "@$Name" when what I want it to look for is "@Sensor1" "@Sensor2" & "@Sensor3".

FMc · Accepted Answer · 2011-05-08 21:23:46Z

12

My advice is to use a better data structure. For example:

use strict;
use warnings;

my %sensors = (
    Sensor1 => ['1.2.3.4',  '1.2.3.5',  '1.2.3.6'],
    Sensor2 => ['2.2.2.1',  '2.2.2.2',  '2.2.2.3'],
    Sensor3 => ['128.0.0.1','128.0.0.2','128.0.0.3'],
);

for my $sensor_name (sort keys %sensors){
    my $ips = $sensors{$sensor_name};
    print "$sensor_name: $_\n" for @$ips;
}

Also see the classic from Mark Jason Dominus: Why it's stupid to `use a variable as a variable name'. The key point is summarized at the end of Part 3 as follows:

One of the biggest problems in all of compter programming is namespace management and data hiding. When you use a symbolic reference you are throwing away forty years of expensive lessons from the School of Hard Knocks.

edited May 8, 2011 at 21:23

answered May 8, 2011 at 20:51

FMc

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1 Comment

stupidking Over a year ago

Thanks a TON!!! I clearly need to spend more time working with hashes as this was such a simple solution.

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