#!/usr/bin/env perl

use warnings;
use strict;

# Open a .txt file

 open(seq1, "<seq1.txt") or die "Please enter two sequences as arguments on the command line\n"
    unless @ARGV == 2;

my ($orig, $comp) = map { uc } @ARGV;
die "Please enter only ATCG sequences\n" if grep { /[^ATCG]/ } $orig, $comp;

die "Sorry, the two sequences you have just entered are of different lengths."
  . "\nPlease try again on the command line.\n" 
    if length $orig != length $comp;

# $comp will transform back to $orig iff it is the reverse complement
$comp =~ y/ATCG/TAGC/;

if ($orig eq reverse $comp) {
    print "Yes, the two sequences are reverse-complement of each other.\n";
    exit;
} else {
    die "Unfortunately, the two sequences are not reverse-complement.\n";
}