python如何分割字符串并重新加入

Question

我在做python中的加密分配，我需要： - 分割字符串 - 替换字母 - 重新加入它，以便它是一个单词。

这是完整的代码，但我卡在def encode(plain)下的for循环。

""" crypto.py 
Implements a simple substitution cypher 
""" 

alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" 
key = "XPMGTDHLYONZBWEARKJUFSCIQV" 

def menu(): 

    print("Secret decoder menu") 
    print("0) Quit") 
    print("1) Encode") 
    print("2) Decode") 
    print("What do you want to do?") 
    response = input() 
    return response 

def encode(plain): 

for i in range(len(plain)): 

    plain = plain.upper() 
    x = plain[i:i+1] 
    y = alpha.index(x) 
    z = key[y:y+1] 
    plain[x] = z 

return plain 

def main(): 

keepGoing = True 
    while keepGoing: 

    response = menu() 

    if response == "1": 

     plain = input("text to be encoded: ") 
     print(encode(plain)) 

    elif response == "2": 
     coded = input("code to be decyphered: ") 
     print (decode(coded)) 

    elif response == "0": 
     print ("Thanks for doing secret spy stuff with me.") 
     keepGoing = False 

    else: 
     print ("I don't know what you want to do...") 

return main 

main() 
menu() 

Answer 1

实现这个替代的最简单的方法是使用字典和列表理解：

alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" 
key = "XPMGTDHLYONZBWEARKJUFSCIQV" 
converter = {a:b for a, b in zip(alpha, key)} 
def encode(s): 
    return ''.join(converter[i] for i in s) 

def decode(s): 
    reverse = {b:a for a, b in converter.items()} 
    return ''.join(reverse[i] for i in s) 

def main(): 
    response = input("Enter 1 to decode, 2 to encode: ") 
    if response == "1": 
     the_string = input("Enter the scrambled string: ") 
     print("The result is ", decode(the_string)) 
    elif response == "2": 
     the_string = input("Enter the plain string: ") 
     print("The result is ", encode(the_string)) 
main() 

Answer 2

如果你想实现自己的解决方案也为@ Ajax1234说。

但更容易string translate

alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" 
key = "XPMGTDHLYONZBWEARKJUFSCIQV" 
crypto = maketrans(alpha, key) 

.... 
the_string = input("Enter the scrambled string: ") 
the_string = the_string.upper() 
encrypted = the_string.translate(crypto)