Basics

Question 1

2-D hash Iteration, print key and value

Answer 1

secret_identities = { "The Batman" => "Bruce Wayne",
  "Superman" => "Clark Kent",
  "Wonder Woman" => "Diana Prince",
  "Freakazoid" => "Dexter Douglas"
}

secret_identities.each { |key, value| puts “#{key}: #{value}”}

Question 2

Declare hash literally

Answer 2

hash = { key1 => value1,
key2 => value2,
key3 => value3
}

Question 3

Declare hash using “new” keyword

Answer 3

my_array = Hash.new

note: “Hash” must be capitalized.

Question 4

Add element to hash declared literally

Answer 4

pets = Hash.new
pets["Donder"] = "dog"

Question 5

Access value in hash using keyword

Answer 5

pets[“Stevie”]

will return “cat”

Question 6

Iteration through array

Answer 6

languages = [“HTML”, “CSS”, “JavaScript”, “Python”, “Ruby”]

languages.each{ |x| puts “#{x}” }

Question 7

If statement

Answer 7

if 5 == 5
print “Yes, it does”
end

Question 8

Else

Answer 8

if 5 == 5
  print "Yes, it does"
else
  print "What a strange world."
end

Question 9

Elsif

Answer 9

puts "Choose a number"
number = Integer(gets.chomp)
if number == 5
  print "Yes, it does"
elsif number > 5
  print "Hmmm"
else
  print "What a strange world."
end

Question 10

Unless

Answer 10

hungry = false

unless hungry
  puts "I'm writing Ruby programs!"
else
  puts "Time to eat!"
end

Question 11

Get input from user

Answer 11

variable_name = gets.chomp

chomp eliminates newline character

Question 12

Split method

Answer 12

puts “Please enter a string…”
text = gets.chomp
words = text.split

creates an array out of string

Question 13

Sort_By Method

Answer 13

h = h.sort_by {|a, b| b }

# the hash h will be sorted by increasing order of b, or the value of each 
# key-value pair

Question 14

Reverse Method

Answer 14

.reverse!

Question 15

Define a method

Answer 15

def welcome
puts “Welcome to Ruby!”
end

Question 16

Splat argument

Answer 16

def what_up(greeting, *bros)
  bros.each { |bro| puts "#{greeting}, #{bro}!" }
end

what_up(“What up”, “Justin”, “Ben”, “Kevin Sorbo”)

Question 17

Blocks

Answer 17

1.times do
puts “I’m a code block!”
end

1.times { puts “As am I!” }

Question 18

Sorting

Answer 18

my_array.sort!

Question 19

Combined comparison operator

Question 20

Length of string

Answer 20

string.length

Question 21

Reverse string

Answer 21

string.reverse

Question 22

Uppercase/Lowercase

Answer 22

string. upcase

string. downcase

Question 23

Multi-line comments

Answer 23

=begin
…
=end

Question 24

! operator

Answer 24

Means change the value, not a copy of value

Question 25

Get input from user

Answer 25

gets

my_var = gets.chomp

Question 26

While loop

Answer 26

counter = 1
while counter < 11
  puts counter
  counter = counter + 1
end

Question 27

Until loop

Answer 27

counter = 1
until counter == 11
  puts counter
  # Add code to update 'counter' here!
  counter = counter + 1
end

Question 28

• Splat Operator

Answer 28

May receive more than one value (as parameter)

Question 29

Code Blocks

Answer 29

blocks as methods that don’t have name

1.times do
puts “I’m a code block!”
end

1.times { puts “As am I!” }

Question 30

Parameter default to false in method definition

Answer 30

def alphabetize(arr, rev=false)
end

Question 31

Getter/Setter in one

Answer 31

attr_accessor :var1, var2, etc.