#!/usr/bin/perl

use strict;
use warnings;
$| = 1;
print "\nSTEP 1: Reserve memory\n";

#my @GLOBAL_DATA;
#$GLOBAL_DATA[0] = '';
#vec($GLOBAL_DATA[0], 9999999, 8) = 44; # Reserves just the right amount.
#$GLOBAL_DATA[1] = 'x' x 10000000;  # Reserves 20000000 bytes
#$GLOBAL_DATA[2] = 'y' x 100000;    # Reserves 200000 bytes
#$GLOBAL_DATA[3] = 'z' x 1000;      # Reserves 2000 bytes

my $AA = 'H';
vec($AA, 9999999, 8) = 44; # Reserves just the right amount.
#my $BB = 'g' x 10000000;  # Reserves double memory!!!

$a = <STDIN>;

print "\nSTEP 2: Do something with the data\n";
DoSomething(\$AA);   # Pass by reference.
PrintIt(\$AA);       # Pass by reference.

$a = <STDIN>;
print "\nSTEP 3: Free up memory\n";

undef $AA;      # Frees up all of it
#undef $BB;      # Frees up only half of it!
#undef $GLOBAL_DATA[0];  # Frees up all of it
#undef $GLOBAL_DATA[1];  # Frees up only half of it!
#splice(@GLOBAL_DATA, 1, 1);  # Frees up half

$a = <STDIN>;

print "\nSTEP 4: Pause\n$a";
exit;

sub DoSomething
{
  my $X = $_[0];

  for (my $i = 0; $i < 60; $i++)
  {
    vec($$X, $i, 8) = $i + 48;     # This operation doesn't use more memory
  }

  for (my $i = 9990000; $i < 9999999; $i++)
  {
    vec($$X, $i, 8) = 65;     # This operation doesn't use more memory
  }
  print "\nDONE.";
}

sub PrintIt
{
  my $X = $_[0];
  print "\nLENGTH OF STRING = ", length($$X), "\n";
  print "\nPREVIEW = ", substr($$X, 0, 60), "\n";
}