#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

sub dec2bin {
    my $bits = shift;
    my $str = unpack("B8", pack("c", $bits));
    return $str;
}

sub bin2dec {
    return unpack("c", pack("B8", substr("0" x 8 . shift , -8)));
}

my @array = (127,-127);

foreach $_ (@array){
    if ($_ < 0) {
	print "Value: $_ is negative\n";
	my $negative_b = dec2bin($_);
	print "Negative binary: ".$negative_b."\n";
	my $negative_d = bin2dec($negative_b);
	print "Negative_binary back to decimal: ".$negative_d."\n";
    }
    else {
	print "Value: $_ is possitive\n";
	my $possitive_b = dec2bin($_);
	print "Possitive binary: ".$possitive_b."\n";
	my $possitive_d = bin2dec($possitive_b);
	print "Possitive_binary back to decimal: ".$possitive_d."\n";
    }
}

__END__

Value: 127 is possitive
Possitive binary: 01111111
Possitive_binary back to decimal: 127
Value: -127 is negative
Negative binary: 10000001
Negative_binary back to decimal: -127