If you have a list of items to process and you don't know how long the list will be at compile-time, use a stack. In Perl, that's as simple as using push to add another element to an array. That's exactly what arturo suggests.

Attempting to keep track of a bunch of names generated on the fly can be tricky, and in this case, it's probably completely unnecessary.

No big shakes in Perl to do this, but you need to read up on references (perldoc perlref and perldoc perlreftut; in hard copy, I recommend Efficient Perl Programming). What you (probably) want is an *array* of references to arrays.

my @list_of_arrays;
foreach (Thing) {
    # get array from thing
    push @list_of_arrays, \@array;
}
# to get at the arrays

foreach my $array (@list_of_arrays) {
    # $array is a reference to an array
    foreach (@$array) {
        # etc
    }
}
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Philosophy can be made out of anything. Or less -- Jerry A. Fodor

Be very, very careful. You are coming close to the following snippet that I use as an interview question. Suppose that CSV is an open filehandle to a file with comma separated values. You want to extract this into an array of arrays. So you write the following snippet:

while (<CSV>) {
  chomp($_);
  @row = split /,/, $_, -1;
  push @data, \@row;
}
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and you get a list of copies of the last row. Why is it going wrong, and how would you fix?

When I ask this I am willing to answer any and all questions about syntax, what constructs do, etc. I stand willing to say what the output will be as they make various modifications to the code. The point isn't familiarity with Perl, it is whether you understand how references work.

Perhaps not surprisingly, I find that people coming from a C background (where you use pointers a lot) tend to do better on this than people who started by learning Perl for scripting/CGI/etc.

You're right. I could have been more explicit in the original code, but I just wanted to give the gist, and so left large (and potentially important) hunks out. Of course I'd use my @array when I got it from "Thing" (which I'll assume is a line from a file which we're splitting to get an array) , à la :

my @list_of_arrays;
while (<FILE>) {
    my @array = split "\t", $_;
    push @list_of_arrays, \@array;
}
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Because that gives you a (reference to a) fresh @array each time through the loop, instead of adding yet another reference to the same global array.

As tilly has pointed out, only giving *parts* of the answer may not be helpful ... So, as they said in that long-ago decade, let's be careful out there =)

Peevish answer to the interview question: "What, don't you people use strict around here? =)"

Philosophy can be made out of anything. Or less -- Jerry A. Fodor

@array_names = ( 'joe', 'bob', 'sue' );
@array_numbers = ( 3.14, 42, 6, 1e100 );
%array_hash;

$array_hash{"names"} = \@array_names;
$array_hash{"numbers"} = \@array_numbers;

1.1:1
1.2:2
1.3:3
2.1:httpd
2.2:sendmail
2.3:portmap
3.1:5
3.2:0
3.3:0
4.1:0
4.2:0
4.3:0
5.1:3
5.2:0
5.3:0
101.1:My error message for httpd
101.2:My error message for sendmail
101.3:My error message for portmap
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OOTOMH:

my %serviceHash;
while (<INPUT>) {
    /^(\d*)\.(\d*)\:(\S*)$/;
    if ( !defined( $serviceHash{ $1 } ) ) {
        my @array = ();
        $serviceHash{ $1 } = \@array;
    }
    $($serviceHash{ $1 })[ $2 ] = $3;
}

You can then do a foreach over the keys of the hash, and do the necessary processing from there. (Update: damn those gt and lt's!)

If you wish to paste in code, please use the <code>...</code></code> tags. That not only gives easy formatting, but it also makes your code available from clicking on "d/l code".

UPDATE
Since tye complained, here is an example of what the CODE tag looks like:

foreach (split //, "Just another Perl hacker,\n") {
  print;
}
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#!/usr/bin/perl

use SNMP_util;

$nameOID = ".1.3.6.1.4.1.2021.2.1.2";
@addOID = qw(.1.3.6.1.4.1.2021.2.1.3 .1.3.6.1.4.1.2021.2.1.4 .1.3.6.1.
+4.1.2021.2.1.5 .1.3.6.1.4.1.2021.2.1.101);
$IP = "127.0.0.1";

(@tempNameArray) = &snmpwalk($IP,$nameOID);
foreach $a (@tempNameArray) {
        ($throw, $name) = split(/:/,$a,2);
        push(@arrayNames, $name);
        }

$control = 0;
foreach $i (@arrayNames) {
        foreach $j (@addOID) {
                (@breakMe) = &snmpwalk($IP,$j);
                        ($throw, $value) = split(/:/,$breakMe[$control
+],2);
                        $resultHash{$i} .= $value.",";
                }
        $control++;
        }

foreach $key (keys %resultHash) {
        ($svcMax, $svcMin, $svcActual, $svcErr) = split(/,/,$resultHas
+h{$key});
        print "-----------------------\n",$key, " values are:\n";
        print "Maximum Services: ", $svcMax, "\n";
        print "Minimum Services: ", $svcMin, "\n";
        print "Actual Services Running: ", $svcActual, "\n";
        print "Error Message: ", $svcErr, "\n";
        }
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