I think the next world for me to conquer in Perl is references; I really seem to struggle with the concept and the use.

I've been reading the perldoc reftut and the concept still escapes me.

What I am understanding is that when you pass a reference to a function, you're not passing a copy of the referant but the referant itself (I think, like I said I don't get references too well). With the code I'm enclosing below, how could I play around with the concept of changing something via the use of a reference and a function and then see the results of the change in the main block of data.

#!/usr/bin/perl -w

use strict;

my %horoscopes = (
        'homer' => 'pisces',
        'marge' => 'sagitarius',
        'bart' => 'cancer',
        'libra' => 'libra',
        );
        
my $reference = \%horoscopes;

capitalize($reference);

sub capitalize {
    foreach (keys(%{$reference})) {
        tr/[a-z]/[A-Z]/;
    }
}

[download]

In reply to pass by reference by bivouac

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.