Ah, thanks! :)

> you declared the lucky case to be the input

In my defence:

To be sure I also tried

 my @array =  ( ("")x3, (undef)x 3, qw/c b a/, ("")x3, (undef) x3 );

which still gives for cmp_undef1 

[
  "",
  "",
  "",
  "",
  "",
  "",
  "a",
  "b",
  "c",
  undef,
  undef,
  undef,
  undef,
  undef,
  undef,
]

[download]

which seems to be another "lucky case".

I don't know how "stable" is defined but it turns out to be not that easy to construct a counterexample without shuffle.

my @array =  ( undef, "", qw/c b a/, "", undef  );

->

["", "a", "b", "c", undef, "", undef]

Cheers Rolf
(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!

In reply to Re^4: Sort undef by LanX
in thread Sort undef by Anonymous Monk

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.