Iterations

Question 1

What would the following code show?

basket = [“apple 1”,”apple 2”,”apple 3”,”apple 4”,”apple 5”,”apple 6”,”apple 7”,”apple 8”,”apple 9”,”apple 10”]

basket.each do |apple|
puts “Taking out #{apple}”
end

Answer 1

"Taking out apple 1"
"Taking out apple 2"
"Taking out apple 3"
"Taking out apple 4"
"Taking out apple 5"
"Taking out apple 6"
"Taking out apple 7"
"Taking out apple 8"
"Taking out apple 9"
"Taking out apple 10"

Question 2

What is the difference between looping and iteration.

Answer 2

Looping is a construct that tells your program to run a certain amount of times until a condition has been met.

Iteration is a way to operate on a collection object, like an array and do something with each element in that collection.

Question 3

What would the following code show?

primary_colors = [“Red”, “Yellow”, “Blue”]
primary_colors.each do |color|
puts “Primary Color #{color} is #{color.length} letters long.”
end

Answer 3

“Primary Color Red is 3 letters long.”
“Primary Color Yellow is 6 letters long.”
“Primary Color Blue is 4 letters long.”

Question 4

What are | | used for in iterations?

Answer 4

| (also known as pipes) are used to hold arguments that are being passed into the iteration.

Question 5

What would the following code look like?

brothers = [“Tim”, “Tom”, “Jim”]
brothers.each do |brother|
puts “Stop hitting yourself #{brother}!”
end

Answer 5

“Stop hitting yourself Tim!”
“Stop hitting yourself Tom!”
“Stop hitting yourself Jim!”

Question 6

What is the shorter way of writing the following code using the { } syntax?

brothers = [“Tim”, “Tom”, “Jim”]
brothers.each do |brother|
puts “Stop hitting yourself #{brother}!”
end

Answer 6

brothers = [“Tim”, “Tom”, “Jim”]

brothers.each{|brother| puts “Stop hitting yourself #{brother}!”}

Question 7

What is the differences between each iteration and collect/map iteration?

Answer 7

If you want the manipulated data returned back to you, use map or collect.

If you want to return the original array, use each.

Question 8

What value will the following code return?

all_odd = [1,3].all? do |number|
number.odd?
end

Answer 8

True

Question 9

What value will the following code return?

all_odd = [1,2,3].all? do |number|
number.odd?
end

Answer 9

False

Question 10

How would you write an iteration that checks to see if all items are even numbers in the following array?

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

Answer 10

array.all? do |number|
number.even?
end

Should return false

Question 11

What value will the following code return?

[1,3].none?{|i| i.even?}

Answer 11

True

Question 12

How would you write an iteration that checks to see if none of the items are even numbers in the following array?

array = [1,3,5,7]

Answer 12

array.none? do |number|
number.even?
end

Should return true

Question 13

What value will the following code return?

[1,2,100].any?{|i| i > 99}

Answer 13

True

Question 14

How would you write an iteration that checks to see if any of the items are greater than 6 in the following array?

array = [1,3,5,7]

Answer 14

array.any?{|i| i > 6}

Should return true

Question 15

What value will the following code return?

the_numbers = [4,8,15,16,23,42]
the_numbers.include?(42)

Answer 15

True

Question 16

What value will the following code return?

the_numbers = [4,8,15,16,23,42]
the_numbers.include?(6)

Answer 16

False

Question 17

What value will the following code return?

[1,2,3,4,5].select do |number|
number.even?
end

Answer 17

[2, 4]

Question 18

How would you write an iteration that only selects odd numbers in the following array?

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

Answer 18

array.select do |number|
number.odd?
end

Should return [1,3,5]

Question 19

What value will the following code return?

[1,2,3].select{|i| i.is_a?(String)}

Answer 19

[ ]

Question 20

What value will the following code return?

[1,2,3].detect{|i| i.odd?}

Answer 20

1

Question 21

What value will the following code return?

[1,2,3].find{|i| i.even?}

Answer 21

2

Question 22

True or False: detect/find method will return the first value that meets the condition that is given.

Answer 22

True

Question 23

What value will the following code return?

[1,2,3,4].detect{|i| i.even?}

Answer 23

2

Question 24

What value will the following code return?

[1,2,3,4].detect{|i| i.is_a?(String)}

Answer 24

nil

Question 25

What value will the following code return?

[1,2].reject{|i| i.even?}

Answer 25

[1]

Question 26

How would you write an iteration that rejects all odd numbers in the following array?

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

Answer 26

array.reject{|i| i.odd?}

Should return [2,4]

Question 27

How would you sort an array of numbers? (There are two ways)

array = [7,3,1,2,6,5,4]

Answer 27

array.sort do |a, b|
  if a == b
    0
  elsif a < b
    -1
  elsif a > b
    1
  end
end

OR

array.sort do |a, b|
a <=> b
end

Question 28

How would you sort an array of strings by the amount of characters they have? (There are two ways)

array=[“love”, “Richard”, “I”]

Answer 28

array.sort do |a, b|
  if a.length == b.length
    0
  elsif a.length < b.length
    -1
  elsif a.length > b.length
    1
  end
end

OR

array.sort do |a, b|
a.length <=> b.length
end

Question 29

What will the following code show?

array=[“Chico”, “Momi”, “Kehau”, “Tomo”, “Rusty”]
array.each_with_index do |name, index|
puts “#{name} is at index #{index} of the array”
end

Answer 29

"Chico is at index 0 of the array"
"Momi is at index 1 of the array"
"Kehau is at index 2 of the array"
"Tomo is at index 3 of the array"
"Rusty is at index 4 of the array"