Please go through References for more information.

--Binoj

  Where people get into trouble is here:

       (@a, @b) = func(@c, @d);
  or
       (%a, %b) = func(%c, %d);

  That syntax simply won't work.  It sets just @a or %a
  and clears the @b or %b.  Plus the function didn't get
  passed into two separate arrays or hashes: it got one
  long list in @_, as always.

@a = a..d;
@b = e..h;

($c, $d) = _ret_arr(\@a, \@b);

#print "@$c \t @$d $/";
#print "@a \t @b $/";

sub _ret_arr {
  my $a = shift;
  my $b = shift;
  my (@tmp_a, @tmp_b) = (@$a, @$b);

  # by reference
  #map{ $_ = uc }@$a,@$b;
  #return $a, $b;
  
  # by values
  #map { $_ = uc } @tmp_a, @tmp_b;
  #return \@tmp_a, \@$tmp_b
}
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#!/usr/bin/perl

use warnings;
use strict;

my ($a, $array_a , $array_b) = p_sub_a( ) ;
print @$array_a[0];
print @$array_a[1];
print @$array_b[0];
print @$array_b[1];
exit 0;



sub p_sub_a {
my $a;
my @array_aa ;
my @array_bb;
$array_aa[0] = "1\n";
$array_aa[1] = "2\n";
$array_bb[0] = "1b\n";
$array_bb[1] = "2b\n";

return ($a, \@array_aa , \@array_bb);
}
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Code tags added by davido.

There's a subtile mistake in your code. You're improperly dereferencing $array_a and $array_b. Yes, it's working for you ok, but consider the following code:

perl -we "@array = qw/one two three/; print @array[1], $/;"
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And the warning is...

Scalar value @array[1] better written as $array[1] at -e line 1.
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Why? Because @array[1] is an array slice of exactly one element. It's similar to @array[0 .. 3], except for being just one element. Perl prefers (for various good reasons) that you use slice semantics when you intend a slice, and scalar semantics when you mean a single element of an array.

Now, why doesn't your example throw a warning? Because you're dealing with references, not simple arrays. I suppose nobody's thought to add such a warning to Perl's repertoire yet, but it probably ought to be there.

The proper way to dereference $array_a would be like this:

print $array_a->[0];
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Hope this clears up a potential future mistake... ;)




Dave