Returning array values

blackadder has asked for the wisdom of the Perl Monks concerning the following question:

I have this call:

@users = @{GetUsers()};
map { $tk{user_list}->insert('end',
                 -itemtype=>'imagetext',
                 -text=>"$_",
                 -image=>$im{ONE}) } 
@users;
[download]

and the GetUsers subroutine is:

sub GetUsers
{
    my $data;
    my $field;
    my @found;
    foreach my $item (@list)
    {
        while (my ($field, $data) = each %{$item})
        {
            next if $field !~ /account/i;
            if (Win32::NetAdmin::UsersExist('',$data))
            {
                print "This '$data' is a user account\n";
                push (@found, $data);
            }
        }
    }
    #return @found; # this does not return correctly.
    #return [qw/One Two Three/]; #this will return correctly.
}
[download]

Obviously I have a problem with returning an array, I need to return the @found array. I am not sure why the return qw/One Two Three/ works and the @found doesn’t.

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Re: Returning array values by DamnDirtyApe (Curate) on Jul 29, 2002 at 08:37 UTC
This `#return @found; # this does not return correctly.` [download] returns ~~an array~~ a list. This `#return [qw/One Two Three/]; #this will return correctly.` [download] returns an array reference. I recommend you go with `return \@found; # this ought to work.` [download] Update: corrected first return type. Thanks podmaster. _______________ D a m n D i r t y A p e Home Node \| Email	[reply] [d/l] [select]
Re: Returning array values by PodMaster (Abbot) on Jul 29, 2002 at 08:41 UTC
You do not have a problem returning an array. You can only return a list, or a reference to an array, commonly referred to as an arrayref. `my @Array = ( 1, 2, 3 ); my $ArrayRef = [ 1, 2, 3 ]; $ArrayRef = \@Array; ## How do you "de-reference" an array reference? @Array = @$ArrayRef; @Array = @{$ArrayRef};` [download] Now I suggest you go and read perldata and perlref, until it all makes sense to you. These are perl basics, and you need to know them by heart. update: `return @array; # DOES NOT RETURN AN ARRAY, IT RETURNS A LIST` [download] Besides knowing the basics perl data structures and references (perl basics), the other important thing to know about is context. japhy wrote an excellent article on that: "List" is a Four-Letter Word. `____________________________________________________` ** The Third rule of perl club is a statement of fact: pod is sexy.	[reply] [d/l] [select]
Re: Re: Returning array values by cybear (Monk) on Jul 29, 2002 at 10:12 UTC
I believe that if you remove the second @ and the () from around the call to GetUsers(): `@users = @{GetUsers()};` leaving you with `@users = GetUsers();` your code should work the way you expected in the first place.	[reply] [d/l] [select]
Re: Returning array values by valdez (Monsignor) on Jul 29, 2002 at 08:40 UTC
This one returns an array `#return @found; # this does not return correctly.` This returns a reference to an array `#return [qw/One Two Three/]; #this will return correctly.` What you need is `return \@found;` that transforms your array into a reference, as needed by the code that calls GetUsers Ciao, Valerio	[reply] [d/l] [select]
Re: Re: Returning array values by blackadder (Hermit) on Jul 29, 2002 at 10:52 UTC
Thanks Guys indeed, the \ @found has worked. I also have tried getting rid of the @{} so the returned value is a single array which also worked, however I will be needing a "list of lists" later on in my script, so I need to use the \ reference. PS: I have read the ‘perldsc’ a number of times but I guess that I am a bit of a slow ‘Scribe’ and there were no examples on referencing on this tutorial. However, amongst your replies, I have enough articles to go on and improve my Perl techniques. Cheers.	[reply]
Re: Re: Re: Returning array values by valdez (Monsignor) on Jul 30, 2002 at 09:11 UTC
You are welcome :-) My way to understand Perl dsc was to Data::Dumper my structures, it is simpler if you visualize them! Happy coding, Valerio	[reply]