Hello Monks,

I am trying to convert decimals to binary and binary to decimals. By using pack and unpack I can convert all positive numbers, in case that a number is negative the process needs to be changed.

Sample of working code demonstrating the problem:

#!/usr/bin/perl
use strict;
use warnings;

my $possitive = 3;
my $negative = -3;

print "My possitive decimal: ".$possitive."\n";
print "My negative decimal: ".$negative."\n";

my $possitive_b = dec2bin($possitive,8);
my $negative_b = dec2bin($negative,8);

print "Possitive binary: ".$possitive_b."\n";
print "Negative binary: ".$negative_b."\n";

my $possitive_d = bin2dec($possitive_b);
my $negative_d = bin2dec($negative_b);

print "Possitive_binary back to decimal: ".$possitive_d."\n";
print "Negative_binary back to decimal: ".$negative_d."\n";

sub dec2bin {
    my $bits      = shift;
    my $possition = shift;
    my $str = unpack("B32", pack("N", $bits));
    $str = substr $str, -$possition;
    return $str;
}

sub bin2dec {
    return unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
}

__END__

My possitive decimal: 3
My negative decimal: -3
Possitive binary: 00000011
Negative binary: 11111101
Possitive_binary back to decimal: 3
Negative_binary back to decimal: 253
[download]

As we can see the negative -3 became 253.

So is there a way to convert the negative decimals to binary and back to decimal?

#!/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 $floating2binary = dec2bin(-127);

print "Binary from floating: ".$floating2binary."\n";

my $binary2floating = bin2dec($floating2binary);

print "Binary from floating: ".$binary2floating."\n";

__END__

Binary from floating: 10000001
Binary from floating: -127
[download]