為什么循環不想繼續

Question

function 提出一個問題，答案應該是“是”或“否”。 它接受問題的文本並返回字母“y”或“n”。 我有一個 Python 代碼，我需要將其轉換為 Ruby。

#Python code 
def ask_yes_no(question):
    response = None
    while response not in ("y", "n"):
        respone = input(question).lower()
    return response

我做了什么

# Ruby code
def ask_yes_no(question)

    guessed_it = false
    response = ""

    puts question
    loop do

        unless (response == ("y" || "n"))  || guessed_it

            response = gets.downcase
            return response #&& guessed_it == true

        end

        break if guessed_it == true 
    end
end

ask_yes_no("
How is the weather?")

Answer 1

The logic of your Ruby code isn't the same as the Python version, and would be just as incorrect in Python as it is in Ruby.

("y" || "n")是對兩個字符串的 boolean 操作； 由於 Ruby 中的所有字符串都為真，因此結果是第一個字符串。 所以因此整個 boolean 操作的結果也是真的，所以unless是假的，並且永遠不會進入塊。

你可以使用include? 與 Python 版本相同：

unless ["y", "n"].include?(response) || guessed_it

但是整個 Ruby 版本可以更直接地翻譯：

def ask_yes_no(question)
    puts question
    response = nil
    until ["y", "n"].include?(response) do
        response = gets.downcase.strip
    end
    response
end

Answer 2

您也可以使用 Ruby 正則表達式。

def ask_yes_no(question)

    until (print question; gets.chomp.downcase =~ /y|n/) do
    end

    $~.to_s

end