It looks like the key deletion needs a bit more checking first. You're deleting all the keys even if they already conform to the capitalization rules. Try running a hash through your functions twice in a row. I think you'll be surprised at whats left... 
use Data::Dumper;

my $hash = {dog=>'cat',PIG=>'cow'};
print Dumper $hash;

force_uc_hash($hash);
force_uc_hash($hash);
print Dumper $hash;

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-Blake

In reply to Re: Force nested hashes to upper/lower case keys by blakem
in thread Force nested hashes to upper/lower case keys by ryddler

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