Referencing/DeReferencing problem

[Tve]

Hi,

I'm starting to look into references, but not everything is clear yet.

This is what I am trying to acheive: I have a list of scalars and I want to build multi-level hash from it (like tree structure).
[tt]
EG:

Given : @array = ("one","two","three"
Result : $hash{one}{two}{three}
[/tt]
This is the small code I wrote, but something is still wrong, probably in the resetting of the reference pointer.
[tt]
# Initialise variables
my @array = ("one","two","three"
my %hash = ();
my $hashref = \%hash;

# Loop for every element in @array
foreach (@array) {

# Add the $_ to hash
$$hashref{$_} = ();

# Redefine the reference pointer
$hashref = \%{$hash{$_}};

}
[/tt]

Can anybody help?

Thanks,

Thierry

 

[hmerrill]

$$hashref{$_} = ();

I don't think that does what you think. $hashref{$_} = (); says add an element to the hash %hashref, where the key is the value of $_, and the value is () (I don't know what that is - did you mean you wanted the value to be a new hash?).

You only need the leading dollar sign in $$hashref{$_} = (); if the value of $hashref{$_} is a reference that you want to dereference.

Maybe a look from a different angle will help:

my %hash = (
"aaa" => {
"date" => "Date string",
"hostname" => "Hostname string"
},

"bbb" => {
"foo" => "foo string",
"bar" => "bar string"
}
);

foreach $key (keys %hash) {
print "\n";
print &quot;key=<$key>\n&quot;;

foreach $cmd (keys %{$hash{$key}}) {
print &quot; cmd=<$cmd>, string=<$hash{$key}{$cmd}>\n&quot;;
}
}

---------------------------------------
That prints out:

key=<aaa>
cmd=<date>, string=<Date string>
cmd=<hostname>, string=<Hostname string>

key=<bbb>
cmd=<foo>, string=<foo string>
cmd=<bar>, string=<bar string>

HTH.
Hardy Merrill
Mission Critical Linux, Inc.

http://www.missioncriticallinux.com