sub PrintAA
{
    my $test       = shift;
    my %aa         = shift;
        print $test . "n";
        foreach (keys %aa)
        {
                print $_ . " : " . $aa{$_} . "n";
                $aa{$_} = $aa{$_} . "+";
        }
}

PrintAA("abc", %fooHash);

sub PrintAA
{
  my $test = shift;
  my $aaRef = shift;

  print $test, "n";
  foreach (keys %{$aaRef})
  {
    print $_, " : ", $aaRef->{$_}, "n";
  }
}

#!/bin/perl -w

use strict;

sub PrintAA
{
    my($test, %aa) = @_;
    print $test . "n";
    foreach (keys %aa)
    {
        print $_ . " : " . $aa{$_} . "n";
    }
}

my(%hash) = ( 'aaa' => 1, 'bbb' => 'balls', 'ccc' => &PrintAA );

PrintAA("test", %hash);

my $test = shift;
my(%aa) = @_;

Reference found where even-sized list expected at xx.pl line 18.
...
Use of uninitialized value in concatenation (.) or string at xx.pl line 13.

sub PrintAA
{
    my $test       = shift;
    my %aa         = @_;
        print $test . "n";
        foreach (keys %aa)
        {
                print $_ . " : " . $aa{$_} . "n";
                $aa{$_} = $aa{$_} . "+";
        }
}

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

PrintAA($foo, %bar);

my %aa = shift;

my $scalar = 5;
my %hash = (a => 1, b => 2, c => 3);

func($scalar, %hash)

sub func {
    my $scalar_var = shift;
    my %hash_var = @_;

    ... Do something ...
}

sub PrintAA ($%)
{
    my $test       = shift;
    my %aa         = ${shift()};
    print "$testn";
    foreach (keys %aa)
    {
        print "$_ : $aa{$_}n";
        $aa{$_} = "$aa{$_}+";
    }
}

PrintAA("test", %hash);

PrintAA("test", %$ref_to_hash);

my %myhash = ( key1 => "val1", key2 => "val2" );

my $href = %myhash

%$href

my $myhref = shift;

keys %$myhref;

sub get_args { ref( $_[0] ) ? shift() : ( @_ % 2 ) ? {} : {@_}; }
sub PrintAA
{
  my $test = shift;
  my $aa = get_args(@_);;
  #then
  $aa->{somearg} #do something
  $aa->{anotherearg} #do something

}

printAA($firstarg,somearg=>1, anotherarg=>2)

printAA($firstarg,{somearg=>1, anotherarg=>2})

my(%hash) = ( 'aaa' => 1, 'bbb' => 'balls', 'ccc' => PrintAA );

PrintAA("test", %hash);