perl -wMstrict -le 'print unpack("i",pack("B32","00000011"))'
3

##</code><code>##

perl -wMstrict -le 'print unpack("B8",pack("i",3))'
00000011

##</code><code>##

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

sub dec2bin {
    my $bits      = shift;
    my $size      = shift;
    my $template  = shift;
    return unpack("B$size", pack($template, $bits));
}

sub bin2dec {
    my $bits     = shift;
    my $size     = shift;
    my $template = shift;
    return unpack($template, pack("B$size",substr("0" x $size . $bits , -$size)));
}

my $int2bin = dec2bin( 3 , 8 , "c" );

print "Int2bin: ".$int2bin."\n";

my $binary2int = bin2dec( $int2bin , 8 , "c" );

print "Decimal from binary: ".$binary2int."\n";