in reply to Testing array of hash values

It looks like this is intended to be a CGI, and yet it doesn't emit the correct response header, so I'll assume this is just a code fragment.

What, exactly, do you expect   @p{'eyes', 'hair', 'etc'} =(); to do? It rather looks like a syntax error to me. If you're trying to pre-load a hash with keys, you might try

my %p; $p{$_} = undef for qw(eyes hair etc);
But that begs the question of what your do_print is trying to do, since   @p{ 'eyes', 'hair', 'etc' } results in a three element array, with each element being undef. Assuming that you're trying to return the heading if and only if any one of the elements is present, you could do
sub do_head { my($heading, @data) = @_; return "<h4>$heading</h4>" if grep { defined($_) } @data; return ""; }