Data Structures

Question 1

What is an array index?

Answer 1

Each element in the array has what’s called an index. The first element is at index 0, the next is at index 1, the following is at index 2, and so on.

Question 2

How do you access an object in an array with the index?

Answer 2

With brackets

array = [5, 7, 9, 2, 0]
array[2]
# returns “9”, since “9”
# is at index 2

Question 3

What are multidimensional arrays?

Answer 3

It’s an array of arrays

Question 4

What are hashes?

Answer 4

A hash is a collection of key-value pairs

Question 5

How do you create a hash?

Answer 5

You use the Hash.new method.
by setting a variable to Hash.new

my_hash = Hash.new

Question 6

How do you add objects to a hash?

Answer 6

We add object to hash with bracket notation:

pets = Hash.new
pets["Stevie"] = "cat"

Question 7

How do you accesses objects in a hash?

Answer 7

We accesses it by using the same method like an array:
puts pets[“Stevie”]

pets = {
  "Stevie" => "cat",
  "Bowser" => "hamster",
  "Kevin Sorbo" => "fish"
}

puts pets[“Stevie”]

Question 8

What do we call it when we loop over a hash or an array?

Answer 8

We call it that we iterate over the hash or array.

Question 9

How do we iterate over arrays?

Answer 9

We use the .each method
numbers = [1, 2, 3, 4, 5]
numbers.each { |element| puts element }

Question 10

How do you iterate over multidimensional arrays?

Answer 10

s.each do | sub_array |
  sub_array.each do | y |
    puts y
  end
end

Question 11

How do you iterate over a hash?

Answer 11

As same as in a Array, nbut you need to have two arguments instead of one.

restaurant_menu.each do | item, price |
puts “#{item}: #{price}”
end