#!/usr/bin/perl
use warnings;
use strict;

# demonstrates strict hash refs 
# Commonly seen error 
# Can't use string ("1") as a HASH ref while "strict refs" in use at ./z line  

my %box;

my $x = 10;
my $y = 10;
my $z = 1;

foreach my $X ( 0 .. $x ) {
    foreach my $Y ( 0 .. $y ) {

    # you cannot create a new hash depth by assigning 
    # a value to it 

       $box{$X}{$Y}{$z} =  1;              #dosn't work and causes error below 
#      $box{$X}{$Y}{$z}{'rect'} = 1 ;      #works 
#      $box{$X}{$Y}{$z}{'rect'} = undef ;  #works 

       $box{$X}{$Y}{$z}{'text'} = 2;     #this gives strict refs error 

    }
}