keys of hash of reference to hash

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

I'm trying to get all of the keys in a referenced hash of a hash. Here's my code:

foreach my $pid (keys %$matches) { 
        foreach my $key (keys $$matches{$pid}) {
               print "$pid:$key:$$matches{$pid}{$key}\n";
        }
}
[download]

The error code tells me that it's not a hash. What is the correct syntax?

thanks as always,

melguin

Comment on keys of hash of reference to hash Download Code

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Re: keys of hash of reference to hash by sauoq (Abbot) on Jan 28, 2003 at 00:55 UTC
I think you want your second foreach to look more like: `foreach my $key (keys %{$matches->{$pid}}) { ... }` [download] -sauoq "My two cents aren't worth a dime.";	[reply] [d/l]
Re: keys of hash of reference to hash by elusion (Curate) on Jan 28, 2003 at 00:59 UTC
Short answer: `foreach my $key (keys %{$matches->{$pid}}) {` Long answer: You can think of `$matches->{$pid}` as the name of your hash. So now that you have the name, you put the hash symbol (%) in front and wrap it in curly braces to disambiguate, and you're all set. elusion : http://matt.diephouse.com	[reply] [d/l] [select]
Re: Re: keys of hash of reference to hash by melguin (Pilgrim) on Jan 28, 2003 at 01:03 UTC
Shout praises to the all-mighty {}!!!	[reply]
Re: keys of hash of reference to hash by Ovid (Cardinal) on Jan 28, 2003 at 01:18 UTC
`#!/usr/bin/perl -w use strict; my $matches = { foo => { 1 => 'one', 2 => 'two' }, bar => { this => 'that' } }; while ( my ($pid,$pid_values) = each %$matches ) { while ( my ($key, $value) = each %$pid_values ) { print "$pid:$key:$value\n"; } }` [download] Cheers, Ovid New address of my CGI Course. Silence is Evil (feel free to copy and distribute widely - note copyright text)	[reply] [d/l]