Hello Monks,

I just learned how to use References, but I am still confused. Currently, I try to write a script that reads a txt file that has 5 columns, each separated by some whitespace. Each Row corresponds to a gene and the columns are the 1. Gene identifyer 2. sequence 3. sequence length 4. GC content 5. CAI. It's not important what that is.

I want to store the individual attributes into a hash with the identifyer as keys, and a reference to an array containing the remaining attributes as the values. When I try to print the hash, perl complains about my infix operator, except when I write the % symbol instead of the $ symbol. But I learned it the other way. In addition, Perl complains that hash references are deprecated. I'm confused.

Here's my code: 
my $file = 'data.txt';
open READ, $file || die "Cannot open $file: $!\n";
my %hash;
while (<READ>){
    chomp;
    my ($id, $seq, $length, $gc, $cai) = split /\s+/, $_;
    $hash{$id} = [ $seq, $length, $gc, $cai ];
}
close (READ);

foreach (keys %hash){
    print $_, "\t", %hash->{$_}[1], "\t", %hash->{$_}[2], "\n";
}

[download]

this code only leads to the warning: Using a hash as a reference is deprecated! When I change the last line to  print $_, "\t", $hash->{$_}[1], ... it also complains: Global symbol $hash requires explicit ...

Can anyone clarify the situation? Thanks in advance!

In reply to references - proper use of infix (arrow) and deprecated hash references by Anonymous Monk

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