Getting GLOB values instead of file content - perl

Question

I am trying to write a script that takes in one file and compares it to the second and then outputs the difference. I had it working, but decided I wanted to get rid of any line that starts with '#." I had to use push as .= was not working. Ever since then I get output like
keys = GLOB(0x23d2d48)
I'm not sure what I am missing.
#!/usr/bin/perl
use warnings;
use lib '/var/www/oooOOoO/lib/Perl';
my #a1;
my #a2;
my %diff1;
my %diff2;
my #diff1;
my #diff2;
my $input_file = "/etc/mysql/conf.d/replication-slave.cnf";
my $input_file2 = "tA.cnf";
open( my $input_fh, "<", $input_file ) || die "Can't open $input_file: $!";
open( my $input_fh2, "<", $input_file2 ) || die "Can't open $input_file: $!";
#a1 = ' ';
for ($input_fh) {
next if /^#/;
push#a1, $_;
}
#a2= ' ';
for ($input_fh2) {
next if /^#/;
push #a2, $_;
}
#diff1{ #a1 } = #a1;
delete #diff1{ #a2 };
# %diff1 contains elements from '#a1' that are not in '#a2'
#k = (keys %diff1);
print "keys = #k\n";
I've tried changing keys to values, but that didn't work.
Thanks

Answer 1

The problem lies in this bit of code:
for ($input_fh) {
next if /^#/;
push #a1, $_;
}
This is creating a single element list containing a filehandle, then pushing that filehandle to #a1. To read from the filehandle you need to wrap it with <>:
while (<$input_fh>) {
next if /^#/;
push #a1, $_;
}
Note I've switched the for to a while as for imposes list context and reads the file all at once whereas while will read one line at a time. You can also remove:
#a1 = ' ';
#a2 = ' ';
Which just adds an extra element to both arrays.

Answer 2

It should work, but you're code's a little messy. I'm also not sure what you're trying to do when you assign #diff1{#a1} = #a1.
Try this re-write and let me know:
#!/usr/bin/perl
use strict;
use warnings;
use lib '/var/www/ooooOOooOoo/lib/Perl';
my $input_file = "/etc/mysql/conf.d/replication-slave.cnf";
my $input_file2 = "tA.cnf";
open my $input_fh, "<", $input_file or die "Can't open $input_file: $!";
open my $input_fh2, "<", $input_file2 or die "Can't open $input_file: $!";
my (#a1, #a2);
while(<$input_fh>){
chomp;
next if /^#/;
push #a1, $_;
}
while(<$input_fh2>){
chomp;
next if /^#/;
push #a2, $_;
}
my %diff1;
#diff1{#a1} = #a1; # What are you actually trying to do here?
delete #diff1{#a2};
# %diff1 contains elements from '#a1' that are not in '#a2'
my #k = (keys %diff1);
print "keys = #k\n";
But you might want to try this approach instead:
my #nums1 = qw(1 2 3 4 5);
my #nums2 = qw(one two three four 5);
my (%compare1, %compare2);
foreach(#nums1){
chomp;
$compare1{$_} = 1;
}
foreach(#nums2){
chomp;
$compare2{$_} = 1;
}
foreach my $key (keys %compare1){
print "$key\n" unless $compare2{$key};
}

Answer 3

Once you have loaded the two arrays, it's better to use a Perl CPAN module to do this kind of taks. I think Array::Utils is a good candidate to achieve your goals. From the module documentation:
use Array::Utils qw(:all);
my #a = qw( a b c d );
my #b = qw( c d e f );
# symmetric difference
my #diff = array_diff(#a, #b);
# intersection
my #isect = intersect(#a, #b);
# unique union
my #unique = unique(#a, #b);
# check if arrays contain same members
if ( !array_diff(#a, #b) ) {
# do something
}
# get items from array #a that are not in array #b
my #minus = array_minus( #a, #b );