Thank you very much for the elaborate reply. As you noted in your reply, the subroutines do return a new, completely different array. In that case, you mentioned: "the values have to be copied one way or another. I'd write it different though: 
sub foo {
        my $array = shift;
        my $copy  = [map {[@$_]} @$array];
        ... Changes in $copy won't affect $array ...
        return $copy;
    }

[download]
As i can see, now $copy is a reference that points to an array of (a new set of) references, each of which contain the same elements as the corresponding reference in @original_array. It could be written in this way though. 
sub foo {
        my $array = shift;
        my @copy  = map {[@$_]} @$array;
        ... Changes in @copy won't affect @array ...
        return \@copy;
    }

[download]
right? And is the reason that you'd copy the elements this way is that it's faster? Again, thanks a lot for your tips, Hadi

In reply to Re^2: dereferencing a double array by perlrocks
in thread dereferencing a double array by perlrocks

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.