$ cat in.txt 
1 22 3 -4

a
b c
d e f
g h i j
k l m n o
$ perl -anle 'print "@F[map $#F-$_*2, 0..$#F/2]"' in.txt 
-4 22

a
c
f d
j h
o m k

[download]

But seriously, there are lots of ways to do this. Just one of many:

while (<>) {
    my @fields = split;
    for (my $i=$#fields; $i>=0; $i-=2) {
        print "$fields[$i] ";
    }
    print "\n";
}

[download]

Update: As for your code, I'd probably have used for instead of map, but other than that it's a decent solution. Just for fun, a different way to write that might be: ++$i&1 and print "$_ " for reverse split; although that might be getting a little too clever ;-) This is a fun exercise in TIMTOWTDI! Update 2: Changed wording a bit.

In reply to Re: printing every 2nd entry in a list backwards (updated) by haukex
in thread printing every 2nd entry in a list backwards 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.