perl print array from subroutine

Question

#! /usr/local/bin/perl 
sub getClusters
{
my @clusters = `/qbo/bin/getclusters|grep -v 'qboc33'`;
chomp(@clusters);
return \@clusters;
}

ummm okay .. how do I get at this array to print since ...

foreach $cluster (getClusters())
{ print $cluster."\n"; }

doesn't seem to work. Thanks.

Answer 1

You are returning a reference, and not dereferencing it anywhere.

foreach $cluster (@{getClusters()})

OR

return @clusters;

Either should fix it (with slightly different effects), with the first one being preferred (your array is kind of big).

You'd use the non-referenced array return for limited number of elements, usually for the purpose of multi-return (thus, usually, limited to 2 or 3, known-length arrays).

Answer 2

If you ran your program under use strict; use warnings;, it would have told you why it failed. As Amadan said, you need to dereference the reference you return.

Answer 3

To make it easy, you can first receive the return value and then print it like

use strict;
use warning;
my $cluster_array = getClusters();
 my @cluster_return = @{$cluster_array};
foreach my $cluster(@cluster_return){
 print"$cluster\n";
}

Answer 4

Perl Solution

#!/usr/local/bin/perl
use strict;
use warnings;

main();

sub main{
   {
      local $"    =  "\n";
      print "@{getClusters()}";
   }
}  

sub getClusters{
   my @tArray  =  `/qbo/bin/getclusters|grep -v 'qboc33'`;
   chomp @tArray;
   return \@tArray;
}

Notice

1. You don't need a foreach loop for debugging, you can just reset the $" operator however to separate array elements however you like (eg, , ,, or how I set it in the code above \n).
2. Returning an array ref is a plus, don't send back the full array (good job)
3. use strict/warnings, especially when debugging
4. try to avoid system calls using ``