Instructions for Week 1 day 3 Ruby/array/loop/hash lab.

tdd_ruby_loop_hash_lab.md

Arrays and Hashes TDD Lab

Working in pairs, create and test-drive the following functions:

1. Given two arrays:

   prices = [ 1.23, 6.98, 8.43, 2.45 ]
   costs = [ 4.23, 1.12, 0.52, 8.67 ]
   

   • create a function that takes two arrays and adds together the lengths of the arrays.

   Expectation: 8

2. Given this array:

     data = [ 1, 2, 3, 4 ,5 ]
   

   • create a function that takes an array of numbers and returns the sum total.

   tips: use a loop in your function!

   Expectation: 15

3. Given this array:

   hogwarts = [ 'Hufflepuff', 'Slytherin', 'Gryffindor', 'Ravenclaw' ]
   

   • create a find_item? method that returns true if an item is contained in a given array and false if not.

   tips: a loop could be useful in this function! tips: ? at the end of a method indicates it's a predicate (it will return true or false)

   Expectation: Ravenclaw => true. Batman => false

4. Given this hash:

   teacher_wallets = {
     'Sandy' => 12,
     'Zsolt'  => 10,
     'Val'  => 1356,
     'Jay' => 1
   }
   

   • create a function that will return the first key name in a hash.

   tips: there is a method on hash called keys - look it up in the docs: http://docs.ruby-lang.org/en/2.0.0/Hash.html

   Expectation: 'Sandy'

5. Given this hash:

   countries = {
     uk: {
       capital: 'London',
       population: 60
     },
     france: {
       capital: 'Paris',
       population: 70
     },
     italy: {
       capital: 'Rome',
       population: 56
     }
   }
   

   • create a function that will return an array of capitals

   tips: you can pass an entire hash to your function e.g. array_of_capitals( countries )

   Expectation: [ 'London', 'Paris', 'Rome' ]