1 - The first parameter to your method will always be the object handle. Try the following:

sub pass{
    shift(); # To ignore the handle
# or
# my $self = shift(); if you want to use it.
    my ( $problem1 )= @_;
    print "$problem1\n";
}
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sub pass{
    my ( $problem1 )= @_; # <-- Your mistake is here
    print "$problem1\n";
}
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sub pass{
    my ( $self, $problem1 )= @_;
    print "$problem1\n";
}
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Style issues.

A couple of things that you probably want to keep in mind while coding. First, if you won't use strict, at least be sure to lexically scope your variables by declaring them with my. For example, in your &passhash method, you don't declare your hash, thus making it a package variable and you lose encapsulation.

• Whenever you are doing OO programming, remember that the first argument to the method is the object.
• Be sure to use proper (or at least consisten) indenting to indicate scope.
• Your constructor should use the two-argument form of bless. Otherwise, you can't inherit from this.

package packa;
use strict;

sub new {
    my $class = shift;
    my $self = {};
    bless $self, $class;
    return $self;
}

sub pass{
    my ( $self, $problem1 )= @_;
    print "$problem1\n";
}

sub passhash{
    my %hash = qw {
        dog voa
        cat mice
    };
    $hash{'problem2'} = [
        ["ha" , "thing", "thorw"], 
        ["good", "ssa" , "ham"],
        ["as", "kid", "wo"],
    ];
    return %hash;
}
[download]

Hope this helps.

Cheers,
Ovid

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I think noone commented so far on your second problem. So let me do that and look at your code first:

%ha = $obj -> passhash;
foreach $key (keys (%ha)){
    if ($key eq "problem2"){
        foreach (@ha{$key}){
            print "array : @{$_}\n";
        }
    }
}
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The entry of the hash %ha corresponding to the key 'problem2' is a reference to an array of arrays. To get to the values of that you have to dereference it: @{$ha{'problem2'}} or equivalent @$ha{'problem2'}.

Now you have an array which elements are references to arrays. You could print the elements of these (referenced) subarrays like this:

foreach my $arr_ref (@$ha{'problem2'}) {
  print "subarray: @{$arr_ref} \n";
}
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Note: Your code works, if you replace the hash slice notation (@ha{$key}) with the dereferencing of the hash entry @$ha{$key}. The hash slice notation is normally used to get multiple values out of hash in one go, you (probably accidently) used it to extract just one value. This is then equivalent to $ha{$key}. An example of a good usage of a hash slice would be

my %hash;
@hash{qw/one two three/} = qw/1 2 3/;
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-- Hofmator