use strict;
use warnings;

print "calling outter from main:\n";
outter();

print "calling inner from main:\n";
inner();

print "calling outter from main:\n";
outter();

sub outter
{
    my $var = 0;
    print "  outter: $var\n";
    print "    calling inner, should increment 0 -> 1\n";

    inner();

    sub inner
    {
        print "    inner: $var -> ";
        $var++;
        print "$var\n";
    }
}

##</code><code>##

Variable "$var" will not stay shared at sub_in_sub.pl line 23.
calling outter from main:
  outter: 0
    calling inner, should increment 0 -> 1
    inner: 0 -> 1
calling inner from main:
    inner: 1 -> 2
calling outter from main:
  outter: 0
    calling inner, should increment 0 -> 1
    inner: 2 -> 3