Python中的凯撒密码函数 [英] Caesar Cipher Function in Python

问题描述

我正在尝试在 Python 中创建一个简单的 Caesar Cipher 函数，该函数根据用户的输入移动字母并在末尾创建一个最终的新字符串.唯一的问题是最终的密文只显示最后一个移位的字符，而不是包含所有移位字符的整个字符串.

I'm trying to create a simple Caesar Cipher function in Python that shifts letters based on input from the user and creates a final, new string at the end. The only problem is that the final cipher text shows only the last shifted character, not an entire string with all the shifted characters.

这是我的代码:

plainText = raw_input("What is your plaintext? ")
shift = int(raw_input("What is your shift? "))

def caesar(plainText, shift): 

    for ch in plainText:
        if ch.isalpha():
            stayInAlphabet = ord(ch) + shift 
            if stayInAlphabet > ord('z'):
                stayInAlphabet -= 26
            finalLetter = chr(stayInAlphabet)
        cipherText = ""
        cipherText += finalLetter

    print "Your ciphertext is: ", cipherText

    return cipherText

caesar(plainText, shift)

推荐答案

我意识到这个答案并不能真正回答您的问题，但我认为无论如何它都有帮助.这是使用字符串方法实现凯撒密码的另一种方法:

I realize that this answer doesn't really answer your question, but I think it's helpful anyway. Here's an alternative way to implementing the caesar cipher with string methods:

def caesar(plaintext, shift):
    alphabet = string.ascii_lowercase
    shifted_alphabet = alphabet[shift:] + alphabet[:shift]
    table = string.maketrans(alphabet, shifted_alphabet)
    return plaintext.translate(table)

事实上，由于字符串方法是用 C 实现的，我们会看到这个版本的性能有所提高.这就是我认为的pythonic"方式.

In fact, since string methods are implemented in C, we will see an increase in performance with this version. This is what I would consider the 'pythonic' way of doing this.

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