I've this code: 
#!/usr/bin/perl -w

use strict;

my $testVar = 1;
my $ptr = \$testVar;

if (my $pid = fork) {
    while (1) {
        print "from parent: $testVar \n";
        print "ptr from parent: $ptr \n";
        sleep 2;
    }
        waitpid($pid, 0);
} else {
    while (1) {
        print "from child: $testVar \n";
        print "ptr from client: $ptr \n";
        $$ptr++;
        sleep 2;
    }
    exit;
}

[download]
which prints this: 
from child: 1 
ptr from client: SCALAR(0x814db78) 
from parent: 1 
ptr from parent: SCALAR(0x814db78) 
from child: 2 
ptr from client: SCALAR(0x814db78) 
from parent: 1 
ptr from parent: SCALAR(0x814db78) 
from child: 3 
ptr from client: SCALAR(0x814db78) 
from parent: 1 
ptr from parent: SCALAR(0x814db78) 
from child: 4 
ptr from client: SCALAR(0x814db78) 
from parent: 1 
ptr from parent: SCALAR(0x814db78)

[download]
Now, I expected the parent to see the newly incremented value of $testVar but I don't. Why is that? Doesn't the reference point to a location in memory that is shared by both the parent & the child?

In reply to trying to understand references by coontie

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.