Re: Using an array in a hash

Your hash creation should look like this:

    %LdnLine = ($j => \@check2);
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The value must be a reference, not an actual array.

To answer your second question--why does it look right when you print out the entire hash--that's because your array is being treated as a list to initialize the hash. It's not treated as an array value to your key $j; the values in @check2 are used as both keys and values in your hash. This is more clear if you do this:

    use Data::Dumper;
    print Dumper \%LdnLine;
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With my dummy values for @check2 and $j this gave me

    $VAR1 = {
              1 => 'foo',
              'bar' => 'baz'
            };
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Which, I'll bet, is not what you were expecting.

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RE: Re: Using an array in a hash by maverick (Curate) on Aug 08, 2000 at 04:36 UTC
Just a bit of elaboration on an excellent post. The keys and values in hashes can only be scalars, you can't directly store a array as a value. But, you can store a refrence to a array in a hash (a reference is a scalar) which is what btrott's code does. When you want to make a reference to another variable use the \ operator. `my $ref_to_array = \@an_array; my $ref_to_hash = \%a_hash; my $ref_to_scalar = \$a_scalar;` [download] Or if you don't want to make a variable and then make a reference, you can initialize them this way. `my $ref_to_array = [1,2,3,4]; my $ref_to_hash = { 'key1' => 'val1', 'key2' => 'val2' }; my $ref_to_scalar = \"some string\n";` [download] The contents can be retrieved like: `print $ref_to_array->[0]; print $ref_to_hash->{'some_key'}; print ${$ref_to_scalar};` [download] All this stuff is explained in the o'reily (sp?) books in great detail. I'd suggest getting them. :) /\/\averick	[reply] [d/l] [select]
RE: RE: Re: Using an array in a hash by tye (Sage) on Aug 08, 2000 at 07:17 UTC
The keys and values in hashes can only be scalars And the keys can only be strings, not just any old scalar. A nit to pick, but an important one (which you probably already knew but that some readers may not have). - tye (but my friends call me "Tye")	[reply]
RE: Re: Using an array in a hash by BlaisePascal (Monk) on Aug 08, 2000 at 04:51 UTC
To elaborate on that second part... When you say `%hash = (a => "foo", b => "bar")` perl treats the "=>" operator as a synonym for ",", so this really looks like `%hash = (a,"foo",b,"bar")`. Perl knows to treat a list assigned to a hash as key/value pairs, so this works right. In your example, where you tried `%hash = (a => (foo,bar, baz))`, perl treats the right hand side as `(a,(foo,bar,baz))`, which is "flattened" into `(a,foo,bar,baz)`, which is then assigned to %hash, yielding `%hash{a} = "foo"` and `%hash{bar} = "baz"`, which isn't what you wanted. The suggestions to use references will do what you want.	[reply] [d/l] [select]