join, like all perl functions, takes lists as arguments (and conveniently provides them in the magical @_ array).
Another good example is substr. It can be used in lvalue context ( special context for subroutines, means you can assign to their result) 
use strict;
use warnings;
my $a = 'abcdefg';
print $a,$/;
print substr($a,0,3),$/;       # rvalue (list)
print $a,$/;
print substr($a,0,3)='bob',$/; # lvalue
print $a,$/;
print scalar( substr($a,0,3,'ABC')),$/; # rvalue (scalar)
print $a,$/;
__END__
abcdefg
abc
abcdefg
bob
bobdefg
bob
ABCdefg

[download]
As you can see substr has special behaviour in lvalue context. RValue means the result is treated as an ordinary value.

In reply to Re: Re: Re: Re: string context and list operators (was Re: Array in scalar context.) by Anonymous Monk
in thread Array in scalar context. by the_0ne

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.