Assuming both of them are called at the top of a subroutine ... my $myarray = shift; puts the first argument to the subroutine into the variable $myarray - no matter what the first argument is, it could be an array reference but it does not have to be. my $myarray = @_; This puts the number of arguments the subroutine was called with into $myarray - evaluating an array in scalar context.

To demonstrate passing an arrayref into a subroutine look at this:

sub print_arr {
  my $count = @_;
  my $arrayref = shift;

  print "I have been called with $count arguments.\n";
  print "$_!!\n" for (@$arrayref)
}

my @arr = qw/Beer Wine PerlMonks/;

print_arr(\@arr);
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If you call it like this print_arr(@arr) then the $arr[0] will be put into $arrayref and an error occurs when perl tries to do @$arrayref because 'Beer' is not a valid reference. (Note that the function now is called with 3 arguments, @arr is flattened out!)

-- Hofmator