python - 我的 Python 凯撒密码程序在 30 后停止移动

Question

我创建了一个函数，将输入的字符串拆分为单词列表，然后将每个单词中的字母替换为移位后的对应字母，但是当我将移位设置为超过 30 时，它的打印结果保持不变。

def ceaser_cipher_encoder(string , num):
        alphabet = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
                    "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]

        new_string = ""
        string_list = string.split(" ")
        new_list = []
        for word in string_list:
                word1 = ""
                for charecter in word:
                        letter_position = alphabet.index(charecter)
                        letter_position_with_shift = letter_position + num
                        if letter_position_with_shift > 25:
                                letter_position_with_shift = 0 + ((letter_position - 25) - 1)
                        word1 += charecter.replace(charecter, alphabet[letter_position_with_shift])

                new_list.append(word1)
                end_string = " ".join(new_list)



        return end_string




message = ceaser_cipher_encoder("hello dad", 35)
print(message)

Answer 1

这里的一个有用技巧是使用模运算符(%)。它会为您处理轮类。

这是我会做的:

def ceaser_cipher_encoder(string , num):
        alphabet = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
                    "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]

        new_string = ""
        for c in string:
                new_string += alphabet[(alphabet.index(c) + num) % len(alphabet)]
        return new_string

假设 c 是“y”，num 是 10。那么 alphabet.index(c) 等于 24，因此移位将返回 34。由于 34 模 26 为 8，因此会将 alphabet[8] ("i") 附加到 new_string。

我使用 len(alphabet) 而不是硬编码 26，以便您可以更改字母表并且代码仍然有效。