Perl: Assigning an array to a hash

You need to read the perlref documentation that talks about references.

There is a difference in how your arrays are stored:

# this is an array in an array variable
@a = (1, 2, 3);

Verses storing a reference to an array:

# this is an array in a scalar variable stored as a reference to the previous array:
$b = \@a;

Functionally that works like a pointer. Thus you can also store this reference in a hash:

$x{'something'} = \@a;

This all works just fine. What you haven't realized is that []s create references to an array, which you can't store in an array variable. You must store it in a scalar. Thus this instead:

$c = [1, 2, 3];
$x{'else'} = $c;

will work.

And accessing and modifying the array before you do the second assignment can be done using:

$c->[3] = '4';

or by using it in array form dereferencing it first

push @$c, 5;

The part you're missing is that @a = [1,2,3] doesn't make an array with 3 elements. It makes an array with one element which is an arrayref.

You meant @a = (1,2,3).

To assign that array to a hash element, you'd use either $b{"x"} = [@a] or $b{"x"} = \@a, depending on what you're trying to do. [@a] makes a new arrayref containing a copy of the current contents of @a. If the contents of @a change after that, it has no effect on $b{x}.

On the other hand, \@a gives you a reference to @a itself. If you then change the contents of @a, that will be visible in $b{x} (and vice versa).