Another approach:

Win8 Strawberry 5.8.9.5 (32)  Sun 08/29/2021 18:20:29
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings

for my $n (qw(2 20 200 2000 20000 200000 2000000)) {
    print "$n -> ";
    print join ' ', unpack '(H2)*', pack 'V', $n;
    print "\n";
    }

^Z
2 -> 02 00 00 00
20 -> 14 00 00 00
200 -> c8 00 00 00
2000 -> d0 07 00 00
20000 -> 20 4e 00 00
200000 -> 40 0d 03 00
2000000 -> 80 84 1e 00
[download]

As with LanX's solution, leading | trailing zeros are present, but they are present in some of the OPed examples as well and I can't figure out when you do and don't want them.

Update: If you're using a 64-bit Perl, you have the 'Q' pack template specifier (update: which uses native endianity by default; see below), so:

Win8 Strawberry 5.30.3.1 (64)  Sun 08/29/2021 20:05:59
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings

for my $n (qw(2 20 200 2000 20000 200000 2000000)) {
    print "$n -> ";
  # print join ' ', unpack '(H2)*', pack 'Q', $n;  # original
    print join ' ', unpack '(H2)*', pack 'Q<', $n;
    print "\n";
    }

^Z
2 -> 02 00 00 00 00 00 00 00
20 -> 14 00 00 00 00 00 00 00
200 -> c8 00 00 00 00 00 00 00
2000 -> d0 07 00 00 00 00 00 00
20000 -> 20 4e 00 00 00 00 00 00
200000 -> 40 0d 03 00 00 00 00 00
2000000 -> 80 84 1e 00 00 00 00 00
[download]

(but you get a lot more trailing zeroes :). (Update: The 'Q' specifier should be used with a '<' little-endian specifier to force the desired byte ordering. 'Q' alone - as used in my originally posted code - uses native byte ordering, whatever that may be.)

---

---

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.