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Learn to Program, 2nd Edition
book

Learn to Program, 2nd Edition

by Chris Pine
March 2009
Intermediate to advanced content levelIntermediate to advanced
194 pages
4h
English
Pragmatic Bookshelf
Content preview from Learn to Program, 2nd Edition

The Hash Class

Another useful class is the Hash class. Hashes are a lot like arrays: they have a bunch of slots that can point to various objects. However, in an array, the slots are lined up in a row, and each one is numbered (starting from zero). In a hash, the slots aren’t in a row (they are just sort of jumbled together), and you can use any object to refer to a slot, not just a number. It’s good to use hashes when you have a bunch of things you want to keep track of but they don’t really fit into an ordered list. For example, we can make a dictionary for little C’s vocabulary:

dict_array = [] ​# array literal; same as Array.new
dict_hash = {} ​# hash literal; same as Hash.new
dict_array[0] = ​'candle'
dict_array[1] = ​'glasses'
dict_array[2] ...
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Publisher Resources

ISBN: 9781680500172Errata