How can I find the number of elements in hash of an arrayref?

Question

$HoA{teletubbies} = [ "tinky winky", "dipsy", "laa-laa", "po" ];

How can I find the number of elements in this hash of arrayref(s)? It should return 4.

Answer 1

Technically, that's not hash of arrays. That's hash of array references. So you should dereference it with @{...} operator and (optionally) force scalar context to convert array into its length.

scalar @{$HoA{teletubbies}}

Answer 2

You can get the size of an array in Perl by evaluating it in a scalar context.

E.g., you can do this explicitly like:

my $size = scalar @{$HoA{teletubbies}};

But you can also do it implicitly in this instance:

my $size = @{$HoA{teletubbies}};

And this being Perl, you could also do it like this:

my $size = $#{$HoA{teletubbies}} + 1;

(The # operator returns the last index of an array, so adding one to it will give you its size).

Answer 3

If you want to do the entire hash then just add a bit more to it:

my $size= 0 ;
foreach ( values %HoA ) { $size += @$_ }