It's a precedence issue, the && is binding stronger than you think. Use extra parens, or use and, which has lower precedence. See perlop for the precedence table. Here's an explanation-by-code:

$ perl -MO=Deparse,-p -e 'substr ( $_,2,8 ) = "        " && substr ( $
+_,15,5 ) = "     " if /^AB/'
(/^AB/ and substr($_, 2, 8) = (substr($_, 15, 5) = '     '));
$ perl -MO=Deparse,-p -e 'substr ( $_,2,8 ) = "        " and substr ( 
+$_,15,5 ) = "     " if /^AB/'
(/^AB/ and ((substr($_, 2, 8) = '        ') and substr($_, 15, 5) = ' 
+    '));
$ echo "AB2014052012345HELLOWORLD" | perl -pe 'substr ( $_,2,8 ) = "  
+      " && substr ( $_,15,5 ) = "     " if /^AB/'
AB     12345     WORLD
$ echo "AB2014052012345HELLOWORLD" | perl -pe 'substr ( $_,2,8 ) = "  
+      " and substr ( $_,15,5 ) = "     " if /^AB/'
AB        12345     WORLD

[download]

In reply to Re: Multiple substr in Perl one-liner by Anonymous Monk
in thread Multiple substr in Perl one-liner by dirtdog

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.