In the first case, you're splitting on a single space ("my @trace = split("\s", ...").

Actually, it's split-ing on the letter 's' because the  \ (backslash) is an escape in a double-quoted string. The escape is unrecognized but passed through, a fact that Perl would have mentioned had warnings been enabled. 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $str = 'the rain in spain falls mainly';
 ;;
 my @ra = split \"\s\", $str;
 printf qq{'$_' } for @ra;
 print '';
 ;;
 @ra = split '\s', $str;
 printf qq{'$_' } for @ra;
"
Unrecognized escape \s passed through at -e line 1.
'the rain in ' 'pain fall' ' mainly'
'the' 'rain' 'in' 'spain' 'falls' 'mainly'

[download]

In reply to Re^2: output difference between backtic and open(). by AnomalousMonk
in thread output difference between backtic and open(). by AltGrendel

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.