Post-increment does not yield a new lvalue, but it does have an lvalue, and does modify the variable. Update: I don't what I was thinking about there. Post-increment has an rvalue. (That's what happens when you try to post a message just before quitting time!) However, below is still semi-interesting. Consider: 

print "$_ and $i\n" for ($i = 1, $i++, $i++);

__OUTPUT__
3 and 3
1 and 3
2 and 3

[download]

The $i is being modified, and the value before the post-increment is used in the list. Playing around, you could do something like: 

print "$_ and $i\n" for (\($i = 1, $i++, $i++));
print \$i , "\n";

__OUTPUT__
SCALAR(0x8176c44) and 3
SCALAR(0x815dcc0) and 3
SCALAR(0x815dad4) and 3
SCALAR(0x8176c44)

[download]
This shows that the first element of the list is the $i variable, and that perl generates two temporary scalars to hold the values of $i prior to increment. Also, the entire list is evaluated before iteration.

Interesting stuff you found here!

In reply to Re: Re: Re: Mysterious for behavior by Belgarion
in thread Mysterious for behavior by Roy Johnson

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.