log(0) is undefined, so I designed a custom function hexbytes which returns a list of 0 padded bytes and special casing '00'.

Please note how I kept the reverse and join outside for generic flexibility of use.

NB: you must still take care of negative $n!

use strict;
use warnings;
use feature "say";

sub hexbytes {
    my ($n)=@_;

    my $nibbles = $n
      ? int( log($n)/log 256 )+1
        : 1  ;                          # 00 has no log

    $nibbles *= 2;                      # 2 nibbles = 1 byte

    return sprintf( '%0*x', $nibbles, $n ) =~ /(..)/g;
}


say "$_ => ", join " ", reverse hexbytes($_) for 0,2,20,200,2000,20000
+,200000;

[download]

C:/Strawberry/perl/bin\perl.exe -w d:/tmp/pm/hex_reverse.pl 
0 => 00
2 => 02
20 => 14
200 => c8
2000 => d0 07
20000 => 20 4e
200000 => 40 0d 03

Compilation finished at Mon Aug 30 15:57:08

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Re^2: Split any number into string of 8-bit hex values (=1 byte) by LanX
in thread Split any number into string of 8-bit hex values (=1 byte) by drsweety

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.