How do I pass a hash to a function in Perl?

Question

I have a function that takes a variable and an associative array, but I can\'t seem to get them to pass right. I think this has something to do with function declarations, h

Answer 1

It looks like you should pass in a reference to a hash.

sub PrintAA
{
   my $test = shift;
   my $aa = shift;
   if (ref($aa) != "HASH") { die "bad arg!" }
   ....
}

PrintAA($foo, \%bar);

The reason you can't do a

my %aa = shift;

is because Perl flattens all the arguments to a subroutine into one list, @_. Every element is copied, so passing in by reference avoids those copies as well.