凯撒密码验证

Question

            def getMode():
                 while True:
                     mode = input('Do you wish to encrypt(e) or decrypt(d) a message: ').lower()
                     if mode in 'encrypt e decrypt d'.split():
                         return mode
                     else:
                         print('Enter either "encrypt" or "e" or "decrypt" or "d".')

            def getMessage():
                 message = input('Enter your message: ')
                 return message

            def getKey():
                 key = 0
                 while True:
                     key = 5
                     return key

            def getTranslatedMessage(mode, message, key):
                 if mode[0] == 'd':
                     key = -key
                 translated = ''

                 for symbol in message:
                     if symbol.isalpha():
                         num = ord(symbol)
                         num += key

                         if symbol.isupper():
                             if num > ord('Z'):
                                 num -= 26
                             elif num < ord('A'):
                                 num += 26
                         elif symbol.islower():
                             if num > ord('z'):
                                 num -= 26
                             elif num < ord('a'):
                                 num += 26

                         translated += chr(num)
                     else:
                         translated += symbol
                 return translated



            mode = getMode()
            message = getMessage()
            key = getKey()

            print('Your translated text is: ', getTranslatedMessage(mode, message, key))

Answer 1

如果只想允许alpha字符：

def getMessage():
    while True:
        message = input('Enter your message: ')
        if message.isalpha():
            return message
        print("Invalid input, text must contain alphabetic characters only.")

允许空格和字母：

 if all(ch.isalpha() or ch.isspace() for ch in message):
            return message

一个dict和使用模将是一个更简洁的方法：

def get_mode():
    while True:
        mode = input('Do you wish to encrypt(e) or decrypt(d) a message: ').lower()
        if mode.lower() in {"e","d"}:
            return mode
        print('Enter either "encrypt" or "e" or "decrypt" or "d".')

def get_message():
    while True:
        message = input('Enter your message: ')
        if all(ch.isalpha() or ch.isspace() for ch in message):
            return message
        print("Invalid input, text must contain alphabetic characters only.")

def get_key():
    return 5

from string import ascii_letters

d = {k: i for i, k in enumerate(ascii_letters)}

enc = ascii_letters

def get_translated_message(mode, message, key):
    if mode == "e":
        return "".join([enc[(d[ch] + key) % 52] if not ch.isspace() else ch for ch in message])
    return "".join([enc[(d[ch] - key) % 52] if not ch.isspace() else ch for ch in message])

mode = get_mode()
message = get_message()
key = get_key()

print('Your translated text is: ', get_translated_message(mode, message, key))