I've tried packing and unpacking every way I know how ...

Last night, I was hacking, packing and unpacking because my understanding of those operations was lacking.

I hope that you will find my examples below of some help.
Bonus question: is my machine big-endian or little-endian?

Rudif

#! perl -w

use strict;

my $string = uc " hack && pack || unpack";
#my $string = 'abcdefgh';
#my $string = uc 'abcdefgh';
#my $string = 'ABCD';

my @hex = unpack 'H*', $string;
print "H   @hex\n";

my @bytes = unpack 'C*', $string;
print "C   @bytes\n";

my @revbytes = reverse @bytes;
my $revbytes = pack 'C*', @revbytes;
print "C   $revbytes\n";


my @shorts = unpack 'S*', $string;
print "S   @shorts\n";

my @revshorts = reverse @shorts;
my $revshorts = pack 'S*', @revshorts;
print "S   $revshorts\n";


my @longs = unpack 'L*', $string;
print "L   @longs\n";

my @revlongs = reverse @longs;
my $revlongs = pack 'L*', @revlongs;
print "L   $revlongs\n";


my @bits = unpack 'B*', $string;
print "B   @bits\n";

my @revbits = reverse @bits;
my $revbits = pack 'B*', @revbits;
print "B   $revbits\n";

++$_ foreach @bytes;
my $bytes = pack 'C*', @bytes;
print "C   $bytes\n";

__END__

H   204841434b202626205041434b207c7c20554e5041434b
C   32 72 65 67 75 32 38 38 32 80 65 67 75 32 124 124 32 85 78 80 65 6
+7 75
C   KCAPNU || KCAP && KCAH 
S   18464 17217 8267 9766 20512 17217 8267 31868 21792 20558 17217
S   ACNP U||K AC P&&K AC H
L   1128351776 640032843 1128353824 2088509515 1347310880
L    UNPK || PACK && HAC
B   001000000100100001000001010000110100101100100000001001100010011000
+100000010100000100000101000011010010110010000001111100011111000010000
+0010101010100111001010000010000010100001101001011
B    HACK && PACK || UNPACK
C   !IBDL!''!QBDL!}}!VOQBDL
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