iterators.rb

musicians = [
  'Jimmy Page',
  'Robert Plant',
  'John Paul Jones',
  'John Bonham'
]

# SELECT
begins_with_r = musicians.select { |musician| musician.start_with?("R") }

# SELECT
begins_with_r = musicians.select do |musician|
  musician.start_with?("R")
end

# EACH
begins_with_r = []
musicians.each do |musician|
  begins_with_r << musician if musician.start_with?("R")
end


# COUNT
begins_with_r_count = musicians.count do |musician|
  musician.start_with?("R")
end


 # EACH
begins_with_r_count = 0
musicians.each do |musician|
  begins_with_r += 1 if musician.start_with?("R")
end


# MAP
first_names = musicians.map do |musician|
  musician.split(' ').first
end

# MAP
upcased = musicians.map do |musician|
  musician.upcase
end

# EACH
upcased = []
musicians.each do |musician|
  upcased << musician.upcase
end

# EACH 2
musicians.each do |musician|
  musician.upcase!
end

# EACH WITH INDEX
musicians.each_with_index do |musician, index|
  musicians[index] = musicians[index].upcase!
end

# EACH WITH INDEX
# musicians.each_with_index do |musician, index|
#   p "#{index} - #{musician}"
# end

# EACH
# index = 0
# musicians.each do |musician|
#   index += 1
#   p "#{index} - #{musician}"
# end


# # FOR LOOP
# index = 0
# for musician in musicians
#   index += 1
#   p "#{index} - #{musician}"
# end