Programa que mostra la cadena complementària a la seqüència introduïda

#!/usr/bin/perl -w

use strict;
my $id;
my @seq;
my $c = 0;
my $r;
my @reverse;


print "ENTER YOUR SEQUENCE IN FASTA FORMAT. TYPE THE IDENTIFICATION MARK IN THE FIRST LINE.\n";
print "IF YOU DON'T HAVE ONE, PLEASE LEAVE THE FIRST LINE EMPTY.\n";
print "ONCE YOU'VE TYPED IT, PRESS ENTER AND CTRL D \n";

$id = ;
@seq = ;

while ($c < scalar(@seq)){;
chomp $seq[$c];
$r = $r . $seq[$c];
$c = $c + 1;


}

$r = "\U$r";
$r =~tr/ATGC/TACG/;
@_= split (//,$r);
@reverse = reverse(@_);


print "\nHERE'S YOUR COMPLEMENTARY SEQUENCE:\n";
print "\n";
print "$id";
print "@reverse\n"; 
print "\n";
print "THANK YOU FOR USING OUR PROGRAM. WE HOPE YOU'VE ENJOYED THE VISIT AND WE WISH TO SEE YOU AGAIN SOON.\n";
print "HAVE A NICE DAY!\n";
print "\n";