Arrays and hashes only store scalars. If you want an AoA or HoA or any such interesting structure, you have to use references.

The example in perlreftut is quite good, I think. I'm not even going to try and duplicate any of his work here. :-)

You might tell them to create some sort of data structure that, using a customer number as a key, would hold their name, address, and phone number - or something along those lines. Let them sweat that for a while, then magically show them how utterly simple refs are (well, OK, maybe not so simple, but feasible). It seems like it's usually a good idea to let students sweat a problem for a while, to give them an idea of its difficulty, before presenting them with a decent solution.

typeglobs arent a bad example either. Demonstrate how all it is is a group of references.

also refs of subroutines are pretty cool

my $aref = get_values();

sub get_values{
my @array = (1..5000000);
return \@array;
}
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Another place you will see references used often is in objects. You don't want to pass around copies of objects, so you pass their memory location (reference). Inside the object, the object refers to itelf as $self, because it dosn't care where it is located.

1) call by reference vs call by value
 &mysub(\@data) vs &mysub(@data)

2) return reference vs return value
 return \@xyz return @xyz

Cheers,

JohnGG

You might find worthy examples in one of the following Tutorials:

intro to references
References quick reference

HTH,