01-recap-array.rb

# Declare an array literal
#               0        1        2        3
characters = ["Hank", "Sheila", "Bob"] # "Uni"

# Array CRUD
# Create (add elements)
characters << "Uni"

# Read
characters[1]

# Update
characters[1] = "Diana"

# Delete
#                  index
characters.delete_at(2)

02-recap-range.rb

# Range

# ..
p 3..10
p (3..10).to_a
# ...
p 3...10
p (3...10).to_a

03-recap-for.rb

# Let's loop with the array
#              0         1        2
#             -3        -2       -1
characters = ["Hank", "Sheila", "Bob"]

# for when given an array
#  el    array
for character in characters
  puts "- #{character}"
end

# Let's loop with just the indexes
#             0 1 2
for index in (0...characters.count)
  # 0 -> characters[0] -> "Hank"
  # 1 -> characters[1] -> "Sheila"
  puts "- #{characters[index]}"
end

# Prefer this
characters.each do |character|
  puts "--- #{character}"
end

04-each-array.rb

#                0        1       2       3
characters = ["Hank", "Sheila", "Bob", "Erik"]

# Let's print hi to all of them
# Hi, Hank! ... etc
# characters.each do |name|
#   puts "Hi, #{name}!"
# end

# Print characters as a numbered list
index = 0
characters.each do |character|
  puts "#{index + 1}. #{character}"
  index += 1
end

characters.each_with_index do |character, index|
  puts "#{index + 1}. #{character}"
end

05-map-array.rb

characters = [
  "Hank",
  "Sheila",
  "Bob",
  "Erik"
]

# Let's change our array to a new array:
# - upcased names
upcased_characters = characters.map do |character|
  character.upcase
end
p upcased_characters

first_letters = characters.map do |character|
  character[0]
end
p first_letters

06-count-array.rb

characters = ["Diana", "Bob", "Dungeon Master", "Erik"]

# Let's count the names with the letter D
d_count = characters.count do |character|
  character.include?("D")
end
p d_count

long_names_count = characters.count do |character|
  character.length > 3
end
p long_names_count

07-select-array.rb

characters = ["Hank", "Dungeon Master", "Bob", "Diana"]

# Select names with less than 5 letters
short_names = characters.select do |character|
  character.length < 5
end
p short_names

# Reject (filter out) names with less than 5 letters
long_names = characters.reject do |character|
  character.length < 5
end
p long_names

08-block-anatomy.rb

# What_is_this?
method_name do |param|
  "code goes here"
end

# And_this?
method_name { |param| "code goes here" }

09-blocks-timer.rb

# Let's write a benchmark tool using yield
def timer
  start_time = Time.now

  # Do stuff here
  yield

  end_time = Time.now

  return end_time - start_time
end

time1 = timer do
  sleep 1
end
p time1

time2 = timer do
  Array.new(100000) { rand }.sort
end
p time2

10-custom-greeting.rb

def full_name_with_message(first_name, last_name)
  sanitized_first_name = first_name.capitalize
  sanitized_last_name = last_name.upcase
  full_name = "#{sanitized_last_name} #{sanitized_first_name}"

  return yield(full_name)
end

greeting1 = full_name_with_message("ringo", "starr") do |name|
  "Olá, #{name}. Como é que tu estás?"
end
puts greeting1

greeting2 = full_name_with_message("john", "lennon") do |name|
  "Hey, how are you, #{name}?"
end
puts greeting2