Question

以下是Codecademy提供的代码：

movies = {
  Memento: 3,
  Primer: 4,
  Ishtar: 1
}

puts "What would you like to do?"
puts "-- Type 'add' to add a movie." 
puts "-- Type 'update' to update a movie."
puts "-- Type 'display' to display all movies."
puts "-- Type 'delete' to delete a movie."

choice = gets.chomp.downcase
case choice
when 'add'
  puts "What movie do you want to add?"
  title = gets.chomp
  if movies[title.to_sym].nil?
    puts "What's the rating? (Type a number 0 to 4.)"
    rating = gets.chomp
    movies[title.to_sym] = rating.to_i
    puts "#{title} has been added with a rating of #{rating}."
  else
    puts "That movie already exists! Its rating is #{movies[title.to_sym]}."
  end

when 'update'
  puts "What movie do you want to update?"
  title = gets.chomp
  if movies[title.to_sym].nil?
    puts "Movie not found!"
  else
    puts "What's the new rating? (Type a number 0 to 4.)"
    rating = gets.chomp
    movies[title.to_sym] = rating.to_i
    puts "#{title} has been updated with new rating of #{rating}."
  end

when 'display'
  movies.each do |movie, rating|
    puts "#{movie}: #{rating}"
   end

when 'delete'
  puts "What movie do you want to delete?"
  title = gets.chomp
  if movies[title.to_sym].nil?
    puts "Movie not found!"
  else
    movies.delete(title.to_sym)
    puts "#{title} has been removed."
  end
else
  puts "Sorry, I didn't understand you."
end

在代码的显示分支中，为什么codecademy使用|movie, rating| and "#{movie}: #{rating}"？没有为电影定义变量。

因为电影变量不应该是|title, rating| and "#{title}: #{rating}"？

Answer 1

movies = {
  Memento: 3,
  Primer: 4,
  Ishtar: 1
}

movies.each do |movie, rating|
  puts "#{movie}: #{rating}"
end

您可以将|movie, rating|视为他们创建的全新变量，以使用each循环。

基本上，each循环遍历movies哈希。在movies哈希中，我们有电影标题及其相对评级。所以当他们迭代那个哈希时，他们基本上会在那里拿起每个细节并使用变量movie, rating，即：

# 1st iteration
movie = Memento
rating = 3

# 2nd iteration
movie = Primer
rating = 4

# 3rd iteration
movie = Ishtar
rating = 1

您可以将这些变量命名为您想要的任何名称，但最好让您的代码易于阅读，因此他们为每个电影标题使用movie，并为每个电影标题使用rating相对评级

变量使用不当？ Codecademy - Ruby - 电影之夜 - 1.你将构建什么

1 个答案: