Short showcase of .each, .map and .map! and what they return

B423_each_and_map.rb

# .EACH, .MAP and .MAP!

numbers = [1, 2, 3, 4, 5] # this is our starting/original array

# EACH
numbers.each do |number|
  number * 2 # simply multiplying each value by 2
end
#=> [1, 2, 3, 4, 5]
p numbers
# the original array is unchanged!

# MAP
numbers.map do |number|
  number * 2 # simply multiplying each value by 2
end
#=> [2, 4, 6, 8, 10]
# the output is a copy of the original in its changed state!
p numbers
# However the original array is still unchanged!
#=> [1, 2, 3, 4, 5]

# MAP!
numbers.map! do |number|
  number * 2 # simply multiplying each value by 2
end
#=> [2, 4, 6, 8, 10]
p numbers
#=> [2, 4, 6, 8, 10]
# .map! is destructive so both the output and the original array are [2, 4, 6, 8, 10]