[Ruby] .map // .select 2

 

arr = ["apple", "bootCAMP", "caRrot", "DaNce"]

new_arr = arr.map { |word| word[0].upcase + word[1..-1].downcase}
 
print new_arr
-------------------------------------
#=>
["Apple", "Bootcamp", "Carrot", "Dance"]

arr = ["apple", "bootCAMP", "caRrot", "DaNce"]

new_arr = arr.map do |ele|
  first = ele[0].upcase
  rest = ele[1..-1].downcase
  first + rest
end

print new_arr
----------------------------------------------
#=>
["Apple", "Bootcamp", "Carrot", "Dance"]

arr = ["apple", "bootCAMP", "caRrot", "DaNce"]

new_arr = arr.map.with_index do |ele, idx|
  first = ele[0].upcase
  rest = ele[1..-1].downcase
  new_word =first + rest
  new_word * idx  
end

print new_arr
------------------------------------------
#=>
["", "Bootcamp", "CarrotCarrot", "DanceDanceDance"] 
# idx 의 숫자만큼 곱해진다. apple의 idx는 0 이므로 empty.