From: Ruby Newbee Date: 2010-01-06T12:39:53+09:00 Subject: being very confused about this hash Hi, irb(main):039:0> hash = Hash.new [] => {} irb(main):040:0> hash['abc'] << 3 => [3] irb(main):041:0> hash.keys => [] irb(main):042:0> hash['def'] => [3] Since I have created a key/value pair with hash['abc'] << 3, why hash.keys show nothing? And, why hash['abc'] << 3 changed the hash's default value (which should be an empty array)? Thanks.