Notes to help remember the interesting tidbits

Ruby_1.9_Hashes.rb

(hash).store
method adds a new value into the Hash
----------------

h = {}
h.store(:a,5)
h => {:a => 5}

----------------

(hash).merge, (hash).merge!, (hash).update #(hash).update is same as (hash).merge
Merges one hash with another
-----------------
h = {:a=>5,:b=>4,:c=>9}
j = {:d=>10,:e=>9}
h.merge(j)
=> {:a=>5, :b=>4, :c=>9, :d=>10, :e=>9}

------------------

(hash).delete_if 
-------------------
(using h from above)

h.delete_if {|k,v| v > 8}
=> {:a=>5, :b=>4}

--------------------

(hash).delete (key)
--------------------
h.delete :b if h.include? :b
=> {:a=>5}

(hash).each_key, (hash).each_value, (hash).each_pair
---------------------
h = {:a=>5, :b=>4, :c=>9, :d=>10, :e=>9}

h.each_key{|k| puts "key: #{k}"}
output: 
key: a
key: b
key: c
key: d
key: e

h.each_value{|v| puts "value: #{v}"}
output: 
value: 5
value: 4
value: 9
value: 10
value: 9

h.each_pair{|k,v| puts "key: #{k}, value: #{v}"}
output:
key: a, value: 5
key: b, value: 4
key: c, value: 9
key: d, value: 10
key: e, value: 9

*note: each_pair is the same as each

(hash).fetch(key)
-----------------
h.fetch(:a) 
=> 5

Error is key not found, or local variable or method undefined if no key exists