Question

I have got two hashes with a foldername as key and its respective files as an array. But I cannot acces the array elements of the passed hash in the getMissingFiles sub (see comments for error message).

Hashes to be compared:

# contains all files
%folderWithFiles1 =
(
    foldername1 => [ qw(a b c d e f g h i j k l m n o p) ],
    foldername2 => [ qw(a b c d e f g h i j k l m n ) ],
)

%folderWithFiles2 =
(
    foldername1 => [ qw(a b d e h i l m n p) ],
    foldername2 => [ qw(a d f g h j m ) ],
)

Compare subroutine (get missing files from hash2 that are not in hash1):

sub getMissingFiles()
{
    my ($hash1, $hash2) = shift; # is it working?
    #my $hash1 = shift; # or do you have to do it separately?
    #my $hash2 = shift;
    my $flag = 0;
    my @missingFiles;

    foreach my $folder (sort(keys %{$hash1}))# (sort(keys %hash1)) not possible?
    {
        for (my $i = 0; $i < @$hash1{$folder}; $i++)
        {
            foreach my $folder2 (sort(keys %{$hash2}))
            {
                foreach my $file2 (@$hash2{$folder2})
                {
                    if ($hash1{$folder}[$i] == $file2) # Error: Global symbol "%hash1" requires explicit package name
                    {
                        $flag = 1;
                        last;
                    }
                }
                if (0 == $flag)
                {
                    push(@missingFiles, $hash1{$folder}[$i]); # Error: Global symbol "%hash1" requires explicit package name
                }
                else
                {
                    $flag = 0;
                }
            }
        }
    }
    return @missingFiles;
}

Calling function:

@missingFiles = &getMissingFiles(\%hash1, \%hash2);

• Is: “my ($hash1, $hash2) = shift;” correct or do you have to do it separately?
• Why is “foreach my $folder (sort(keys %hash1))” not possible?
• Is there a more efficient way than using 4 loops?

Answer 1

In getMissingFiles(), just as you dereference $hash1 and $hash2 to get the keys, you also need to dereference them to get the values:

@folder_files = @{ $hash1->{$folder1} }; 

or alternatively,

@folder_files = @{ $$hash1{$folder} };

And you can do this to get individual files:

$file = $hash1->{$folder}[$i];