使用用户输入的变量NoMethodError访问哈希密钥
我在尝试使用用户输入的变量访问哈希时收到此错误消息：“undefined method`index’for nil：NilClass（NoMethodError）”
这应该说明我的问题好一点……一旦字符串“n”存储在变量中，变量就不能再访问哈希并返回nil。 为什么？
[6] pry(main)> line = "n" => "n" [7] pry(main)> subway[:line] => nil [8] pry(main)> subway[:"n"] => ["timessquare", "34th", "28th", "23rd", "unionsquare", "8th"] [9] pry(main)> line => "n" This is the .rb file n = ["timessquare", "34th","28th","23rd","unionsquare","8th"] l = ["8th", "6th", "unionsquare","3rd","1st"] six = ["grandcentral","33rd","28th","23rd","unionsquare","astorplace"] subway = {:n=>n, :l=> l, :six=>six} puts "Where would you like to go?" destination = gets.strip.chomp.downcase.delete(" ") puts "What line is that on?" endline = gets.strip.chomp.downcase.delete(" ") puts "What station will you be departing from?" location = gets.strip.chomp.downcase.delete(" ") puts "What line is that on?" startline = gets.strip.chomp.downcase.delete(" ") if startline == endline puts (startline.index(destination)-startline.index(location)).abs else puts "You have #{(subway[:startline].index(location) - subway[:startline].index("unionsquare")).abs} stops until transfer" puts "After you have #{(subway[:endline].index(destination) - subway[:endline]index("unionsquare")).abs} until your destination" end 你只需要将线转换为符号： subway[line.to_sym]