print $col,"\n"; ## string of all the columns I am interested in
...
@line = @line[$col]; ## I am getting the error since, 
                     # $line is a string and not numeric..
                     # It works if you do
                     # @line[1,2,5,6,70,71,75,100,112,114]

##</code><code>##

#!/usr/bin/env perl -l

use strict;
use warnings;

my @line = qw{A B C D};
print "All line elements: @line";

my $col = '2,3';
print "Indices I want: $col";

my @indices = split /,/ => $col;

my @wanted_elements = @line[@indices];

print "Wanted elements: @wanted_elements";

##</code><code>##

All line elements: A B C D
Indices I want: 2,3
Wanted elements: C D