Control Flow

Question 1

true && true # => ___
true && false # => ___
false && true # => ___
false && false # => ___

Answer 1

true
false
false
false

Question 2

true || true # => ___
true || false # => ___
false || true # => ___
false || false # => ___

Answer 2

true
true
true
false

Question 3

false || false

true or false?

Answer 3

false

Question 4

!true # => ____

!false # => ____

Answer 4

false

true

Question 5

!true && !true

true or false?

Answer 5

false

Question 6

!true && (!true || 100 != 5**2)

true or false?

Answer 6

false

Question 7

true || !(true || false)

true or false?

Answer 7

true

Question 8

Set the output to write “Ruby!” five times.

Answer 8

5.times { puts “Ruby!” }

Question 9

Write an array of numbers 1-5. Note the brackets.

Answer 9

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

Question 10

1. Write a hash “profile” with your name, city, and state.
2. Call on the city within that profile.
3. Create a new hash called “favorites”.
4. Add a value pair where “baseball” = “Twins”.

Answer 10

profile = {
  "name" => "Spencer"
  "city" => "Minneapolis"
  "state" => "MN"
}

puts profile[“city”]

favorites = Hash.new
favorites["baseball"] = "Twins"

Question 11

example = [“Car”, “Boar”, 45, 9.9, true]

Access “45” in the array.

Answer 11

puts example[2]

Question 12

1. Create an array “team” of these players and their number:
   Towns = 32
   Russell = 0
   Beasley = 5
2. Call on the array to form a statement of what each number every player wears.

Answer 12

team = {
  "Towns" => "32",
  "Russell" => "0",
  "Beasley" => "5",
}

team.each do |player, number|
puts “#{player} wears #{number}.”
end

Question 13

Define a greeter method that takes a single string parameter, name, and returns a string greeting that person.

Answer 13

def greeter(name)
  return "Hello, #{name}!"
end

Question 14

Define a by_three? method that takes a single integer parameter, number, and returns true if that number is evenly divisible by three and false if not.

Answer 14

def by_three?(num)
  if num % 3 == 0
    return true
  else
    return false
  end
end

Question 15

What’s the difference between “.sort” and “.sort!”?

Answer 15

.sort - will sort a copy

.sort! - will sort current array, replacing old with the sorted version.

Question 16

You have four books. Sort your books in descending order.

Display the result in the console.

Answer 16

books.sort! do |firstBook, secondBook|
secondBook <=> firstBook }

puts books

Question 17

Create a method, welcome, that puts “Welcome to Ruby!” After defining your method, call it.

Answer 17

def welcome
puts “Welcome to Ruby!”
end

welcome

Question 18

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

Add a block that multiplies each item by itself and puts the result to the console.

Answer 18

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

my_array.each do |num|
puts num * num
end

Question 19

Define a method to alphabetize an array (arr) or list in descending order (rev) if called upon.

Answer 19

def alphabetize(arr, rev = false)
  arr.sort!
    if rev == true
      arr.reverse!
    else
      return arr
    end
end

Question 20

How do you convert a string to a symbol?
How do you convert a symbol to a string?
How do you convert a string to an integer?
How do you convert something to a float?

Answer 20

.to_sym
.to_s
.to_i
.to_f

Question 21

olympic_trials = {
  Sally: 9.58,
  John: 9.69,
  Bob: 14.91
}

Grab all names/times that are 10.00 or better.

Answer 21

olympic_trials { |name, time| time < 10.00 }

Question 22

Write a method asking if a number is a multiple of 3 with the output resulting in true or false.

Answer 22

def multiple_of_three(n)
n % 3 == 0 ? “True” : “False”
end

Question 23

Write a loop that only puts the even values of my_array

Answer 23

my_array.each { |num| puts num unless num % 2 !=0 }

Question 24

What is the shortcut for .push?

Answer 24

&laquo_space;(shove)
alphabet &laquo_space;“x”

+ works on variables too

Question 25

Write a method, square, that takes a number as an argument and implicitly returns the square of that number.

Answer 25

def square(num)
num*num
end

Question 26

create a proc called cube that cubes a number

Answer 26

cube = Proc.new { |x| x ** 3 }