Collections

• Arrays
• Hashes
• Ranges

Ref. WGR Chapter 9, Collection and container objects

Array vs. Hash

• An array is an ordered list of values
• A hash is an unordered set of key/value pairs

• An array has an index that must be an integer
• A hash has a key that can be any object (number, string, another hash, etc.)

• Array is also called List, Vector
• Hash is also called Map, Dictionary

• Array literals are defined with [ ]
• Hash literals are defined with { }
• both are accessed with [ ]