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Old 09-06-2006, 02:35 PM   #1
Registered: Oct 2003
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Perl hash of hashes

I am new in Perl and im trying to understand the hash of hashes. Unfortunately my text book or various man pages do not clarify ( or
simply i dont get it) my confusion.

In the following line:
my ($source, $destination, $bytes) = split;
$total_bytes{$source} {$destination} += $bytes;

i have a hash %total_bytes . Can you explain the 2 pairs of curly brackets?

Is this an anonymous hash where keys and values are set by the split function?

for simple hashes it would have been $total_bytes{'key'} ='value'

so because this is more complicated we add not only the value($destination) but the key($source) as well

What do you think
Old 09-06-2006, 07:02 PM   #2
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$total_bytes{$source} {$destination}
Well, you said yourself it is a two-dimensional hash.

{$source} is assigning the value of $source to the key of the main hash, and {$destination} is assigning the value of $destination to the key of the hash within the main hash. Make sense?

%total_bytes is a hash of which one key is {$source} whose value is another hash of which the {$destination} key's value is += $bytes
Old 09-07-2006, 04:43 AM   #3
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Thank you bulliver


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