View Subcategory
Check if a key exists in a map
Given a map pets
{joe:cat,mary:turtle,bill:canary} print "ok" if an pet exists for "mary"
ruby
puts "ok" if map.has_key?('mary')
puts "ok" if map['mary'] # Only works if map entry can't be nil or false
Retrieve a value from a map
Given a map pets
{joe:cat,mary:turtle,bill:canary} print the pet for "joe" ("cat")
ruby
puts map['joe']
Add an entry to a map
Given an empty pets map, add the mapping from
"rob" to "dog"
ruby
pets['rob']='dog'
Remove an entry from a map
Given a map pets
{joe:cat,mary:turtle,bill:canary} remove the mapping for "bill" and print "canary"
ruby
puts map.delete :bill
