虽然循环失败 - 凯撒密码

Question

我有一个问题，当我要求我的程序退出时，打印就像我问它，但显示我的选项菜单以及不断。

所以我得到这样的：

>>> 
(S)huffle a message. 
(U)nshuffle a message. 
(Q)uit program. 
Choose a option to begin: q 
Goodbye! 
(S)huffle a message. 
(U)nshuffle a message. 
(Q)uit program. 
Choose a option to continue: 

，我想如果我选择“Q”它来显示这一点：

>>> 
(S)huffle a message. 
(U)nshuffle a message. 
(Q)uit program. 
Choose a option to begin: q 
Goodbye! 

这里是我的完整代码，请解释一下为什么我的菜单是重新打印，我是否让我的while循环错误，或者是在我的代码中不合适的地方？

def hw8(): 

    print('(S)huffle a message.') 
    print('(U)nshuffle a message.') 
    print('(Q)uit program.') 

    x = input('Choose a option to begin: ') 

    if x == 'Q' or x == 'q': 
     print('Goodbye!') 

    while x != 'q' or 'Q' : 

     if x == 'S' or x == 's': 
      y = input('Enter a message to shuffle: ') 

      q1 = '' 

      for i in y: 
       if ord(i) in range(65,90) or ord(i) in range(97,122): 
        q = chr(ord(i) + 1) 
        q1 = q1 + q 
       elif ord(i) == 90: 
        q = chr(ord(i) + 7) 
        q1 = q1 + q 
       elif ord(i) == 122: 
        q = 'A' 
        q1 = q1 + q 
       else: 
        q = i 
        q1 = q1 + q 
      print(q1) 



     if x == 'U' or x == 'u': 
      f = input('Enter a message to unshuffle: ') 

      t2 = '' 

      for i in f: 
       if ord(i) in range (66,91) or ord(i) in range(98,123): 
        t = chr(ord(i) - 1) 
        t2 = t2 + t 
       elif ord(i) == 65: 
        t = 'z' 
        t2 = t2 + t 
       elif ord(i) == 97: 
        t = 'Z' 
        t2 = t2 + t 
       else: 
        t = i 
        t2 = t2 + t 

      print(t2) 

     print('(S)huffle a message.') 
     print('(U)nshuffle a message.') 
     print('(Q)uit program.') 

     x = input('Choose a option to continue: ') 


hw8() 

我希望程序洗牌的消息，或unshuffling消息后，以及在开始显示菜单，而不是在用户已经要求通过选择“Q”退出程序。

---

编辑的代码：

def hw8(): 

    print('(S)huffle a message.') 
    print('(U)nshuffle a message.') 
    print('(Q)uit program.') 

    x = input('Choose a option to begin: ') 

    while x != 'q' or x != 'Q' : 

     if x == 'S' or x == 's': 
      y = input('Enter a message to shuffle: ') 

      q1 = '' 

      for i in y: 
       if ord(i) in range(65,90) or ord(i) in range(97,122): 
        q = chr(ord(i) + 1) 
        q1 = q1 + q 
       elif ord(i) == 90: 
        q = chr(ord(i) + 7) 
        q1 = q1 + q 
       elif ord(i) == 122: 
        q = 'A' 
        q1 = q1 + q 
       else: 
        q = i 
        q1 = q1 + q 
      print(q1) 



     if x == 'U' or x == 'u': 
      f = input('Enter a message to unshuffle: ') 

      t2 = '' 

      for i in f: 
       if ord(i) in range (66,91) or ord(i) in range(98,123): 
        t = chr(ord(i) - 1) 
        t2 = t2 + t 
       elif ord(i) == 65: 
        t = 'z' 
        t2 = t2 + t 
       elif ord(i) == 97: 
        t = 'Z' 
        t2 = t2 + t 
       else: 
        t = i 
        t2 = t2 + t 

      print(t2) 

     print('(S)huffle a message.') 
     print('(U)nshuffle a message.') 
     print('(Q)uit program.') 

     x = input('Choose a option to continue: ') 

     if x == 'Q' or x == 'q': 
      print('Goodbye!') 


hw8() 

新输出：

>>> ================================ RESTART ================================ 
>>> 

(S)huffle a message. 
(U)nshuffle a message. 
(Q)uit program. 
Choose a option to begin: s 
Enter a message to shuffle: hello 
ifmmp 
(S)huffle a message. 
(U)nshuffle a message. 
(Q)uit program. 
Choose a option to continue: q 
Goodbye! 
(S)huffle a message. 
(U)nshuffle a message. 
(Q)uit program. 
Choose a option to continue: 

Answer 1

你的问题是这样的一行：

while x != 'q' or 'Q' : 

的问题是，Q本身总是返回True，所以表达将永远是真实的。尝试改变符合：

while x != 'q' and x != 'Q' : 

Answer 2

x != 'q' or 'Q'被处理为(x != 'q') or 'Q'，和“Q”始终是真实的。

这将更好的是： x not in 'qQ'或x.lower() != 'q'