HASH(0x1970c80) in Perl script - perl

Question

I have the following code:
#!/usr/bin/perl
use warnings;
use strict;
my $count;
my #chomp;
my $length;
my %hash;
my $orf;
open FILE, "<", $ARGV[0];
while ( my $line = <FILE> ) {
if ( $line =~ /LOCUS/ ) {
$count++;
$line =~ s/ +/\t/g;
#chomp = split( /\t/, $line );
$length = $chomp[2];
$hash{$count}->{length} = $length;
}
elsif ( $line =~ /misc_feature (\w+)\.\.(\w+)/ ) {
$orf = $2 - $1;
if ( !defined $hash{$count}->{orf} or $hash{$count}->{orf} < $orf ) {
$hash{$count}->{orf} = $orf;
}
}
}
for my $key (%hash) {
print $key. "\n";
# print $hash{$key}->{"orf"}."\t".$hash{$key}->{"length"}."\n";
}
that gives the following output:
HASH(0x140ae60)
13891
HASH(0x18d4060)
5056
HASH(0x15c4968)
15612
HASH(0x1970c80)
18787
HASH(0x1a98448)
7684
I do not understand why is it? It should print $count value (for example 1, 2, 3...). In fact, it is printed, but with that HASH(0x over there.

Answer 1

You should use
for my $key (keys %hash)
{ ... }

Answer 2

You need to deference since it's a hash of hashes:
use warnings;
use strict;
for my $length (keys %hash) {
print "$length\n";
for my $count (keys %{$hash{$length}}) {
print "$count\n";
}
}

Answer 3

That's because you're building a hash-of-hashes:
$hash{$count}->{length} = $length;
when you print out $hash{whatever}, you're trying to print out that "inner" hash, which is where your HASH(0xXXXXXXX) output it coming from.

Answer 4

for my $key (keys %hash) {
print $key."\n";
# print $hash{$key}->{"orf"}."\t".$hash{$key}->{"length"}."\n";
}

Answer 5

As many others says, you need to use keys if you want get the keys. So:
for my $key (keys %hash)
^^^^
here
the full example:
use strict;
use warnings;
use feature 'say';
use Data::Dumper;
my %hash = (
cnt13 => {
'length' => 'len13'
},
'cnt12' => {
'orf' => 'orf12',
'length' => 'len12'
},
'cnt11' => {
'length' => 'len11'
},
'cnt10' => {
'orf' => 'orf10',
'length' => 'len10'
}
);
for my $key (keys %hash) {
say "key is CNT: $key";
for my $subkey (keys %{$hash{$key}} ) {
say "\tGot a subkey: $subkey with a value: $hash{$key}->{$subkey}";
}
}
say Dumper \%hash;
prints:
key is CNT: cnt11
Got a subkey: length with a value: len11
key is CNT: cnt13
Got a subkey: length with a value: len13
key is CNT: cnt12
Got a subkey: orf with a value: orf12
Got a subkey: length with a value: len12
key is CNT: cnt10
Got a subkey: length with a value: len10
Got a subkey: orf with a value: orf10
$VAR1 = {
'cnt11' => {
'length' => 'len11'
},
'cnt13' => {
'length' => 'len13'
},
'cnt12' => {
'orf' => 'orf12',
'length' => 'len12'
},
'cnt10' => {
'length' => 'len10',
'orf' => 'orf10'
}
};