Inverting a Hash's Key and Values in Perl

Question

I would like to make the value the key, and the key the value. What is the best way to go about doing this?

Answer 1

Adapted from http://www.dreamincode.net/forums/topic/46400-swap-hash-values/:

Assuming your hash is stored in $hash:

while (($key, $value) = each %hash) {    $hash2{$value}=$key; }  %hash=%hash2; 

Seems like much more elegant solution can be achieved with reverse (http://www.misc-perl-info.com/perl-hashes.html#reverseph):

%nhash = reverse %hash; 

Note that with reverse, duplicate values will be overwritten.

Answer 2

Use reverse:

use Data::Dumper;  my %hash = ('month', 'may', 'year', '2011'); print Dumper \%hash; %hash = reverse %hash; print Dumper \%hash;