Re: Returning multiple arrays

Hope this helps

Regards
Manoj

#!/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);
}
[download]

Code tags added by davido.

Comment on Re: Returning multiple arrays Download Code

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Re^2: Returning multiple arrays by davido (Cardinal) on Feb 17, 2005 at 16:55 UTC
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], $/;"` [download] And the warning is... `Scalar value @array[1] better written as $array[1] at -e line 1.` [download] Why? Because `@array[1]` is an array slice of exactly one element. It's similar to `@array[0 .. 3]`, except for being just one element. Perl prefers (for various good reasons) that you use slice semantics when you intend a slice, and scalar semantics when you mean a single element of an array. Now, why doesn't your example throw a warning? Because you're dealing with references, not simple arrays. I suppose nobody's thought to add such a warning to Perl's repertoire yet, but it probably ought to be there. The proper way to dereference `$array_a` would be like this: `print $array_a->[0];` [download] Hope this clears up a potential future mistake... ;) Dave	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^2: Returning multiple arrays
by davido (Cardinal) on Feb 17, 2005 at 16:55 UTC

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], $/;"
[download]

And the warning is...

Scalar value @array[1] better written as $array[1] at -e line 1.
[download]

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];
[download]

Hope this clears up a potential future mistake... ;)

Dave

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