Python中替换密码的问题

很抱歉代码太长，我已经尝试了一段时间来修复主函数中出现的错误。不知道从这里到哪里去

• 编辑以修复缩进问题，现在函数运行，但命令 “输入命令（getKey、changeKey、encrypt、decrypt、quit）：”重复执行，而不考虑getKey以外的输入。当输入getKey时，出现错误“'SubstitutionCipher'对象没有属性'getKey'”
• 第二次编辑类替换密码允许函数至少为getKey提供一个输出

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我不确定这些是语法、缩进、其他特性的问题，还是它们的组合问题。我很感谢你的一些见解，因为我已经尝试了几天来解决这个问题。当前的问题是，中断在循环之外，当更改缩进时，我会收到一个错误，称为意外缩进。

这是您的代码，缩进已修复，还有一些其他修复。这似乎奏效了

import random
#A global constant defining the alphabet
LCLETTERS = "abcdefghijklmnopqrstuvwxyz"

#function to check if given key is valid or not

def isLegalKey(key):
    return ( len(key) == 26 and all ( [ch in key for ch in LCLETTERS ] ) )

#function to generate random key
def makeRandomKey():
    lst = list( LCLETTERS )
    random.shuffle( lst )
    return ''.join( lst )



class SubstitutionCipher:
    def __init__ (self, key = makeRandomKey() ):
        self._key = key

    def getKey( self ):
        return self._key

    def setKey( self, newKey ):
        self._key = newKey

    def encryptText( self, plaintext ):
        alphabet = LCLETTERS
        key = self._key
        text = plaintext

        result = ""
        for letter in text:
            if letter.lower() in alphabet:
                result += key[alphabet.find(letter.lower())]
            else:
                result += letter

        return result

    def decryptText( self, ciphertext):
        alphabet = LCLETTERS
        key = self._key
        text = ciphertext

        result = ""
        for letter in text:
            if letter.lower() in key:
                result += alphabet[key.find(letter.lower())]
            else:
                result += letter

        return result

#main function
def main():
    flag =0
    cipherFun = SubstitutionCipher()
    while flag ==0:
        print("Enter a command (getKey, changeKey, encrypt, decrypt, quit): ")
        str = input()

        if str == 'getKey':
            print(cipherFun.getKey())

        elif str == 'changeKey':
            while True:
                print("Enter a valid cipher key, 'random' for a random key, or 'quit' to quit: ")
                cipher = input()

                if cipher == 'random':
                    cipherFun.setKey(makeRandomKey())
                    break
                elif cipher == 'quit':
                    break
                elif isLegalKey(cipher) == False:
                    print("Illegal key entered. Try again")
                else:
                    cipherFun.setKey(cipher)
                    print("New cipher key: ", cipherFun.getKey())
                    break
        elif str == 'encrypt':
            print("Enter a text to encrypt: ")
            str = input()
            res = cipherFun.encryptText(str)
            print("The encrypted text is: ", res)

        elif str == 'decrypt':
            print("Enter a text to decrypt: ")
            str = input()
            res = cipherFun.decryptText(str)
            print("The decrypted text is: ", res)

        elif str == 'quit':
            print("Thanks for visiting!")
            flag =1

        else:
            print("command not recognized. Try again")

main()

---

您看到了哪些错误，在哪些行中？将错误的完整回溯显示为问题中格式正确的文本。您最大的问题是以

if（str=='getKey'）：

开头的每一行都需要缩进，以便它们是

while

循环的一部分。另外请注意，Python中的

if

语句不需要括号。验证

密码的部分也需要缩进，以成为
while
循环内部
的一部分。您有巨大的缩进问题，至少如本文所示。替换密码中的成员函数也必须缩进。
import random
#A global constant defining the alphabet
LCLETTERS = "abcdefghijklmnopqrstuvwxyz"

#function to check if given key is valid or not

def isLegalKey(key):
    return ( len(key) == 26 and all ( [ch in key for ch in LCLETTERS ] ) )

#function to generate random key
def makeRandomKey():
    lst = list( LCLETTERS )
    random.shuffle( lst )
    return ''.join( lst )



class SubstitutionCipher:
    def __init__ (self, key = makeRandomKey() ):
        self._key = key

    def getKey( self ):
        return self._key

    def setKey( self, newKey ):
        self._key = newKey

    def encryptText( self, plaintext ):
        alphabet = LCLETTERS
        key = self._key
        text = plaintext

        result = ""
        for letter in text:
            if letter.lower() in alphabet:
                result += key[alphabet.find(letter.lower())]
            else:
                result += letter

        return result

    def decryptText( self, ciphertext):
        alphabet = LCLETTERS
        key = self._key
        text = ciphertext

        result = ""
        for letter in text:
            if letter.lower() in key:
                result += alphabet[key.find(letter.lower())]
            else:
                result += letter

        return result

#main function
def main():
    flag =0
    cipherFun = SubstitutionCipher()
    while flag ==0:
        print("Enter a command (getKey, changeKey, encrypt, decrypt, quit): ")
        str = input()

        if str == 'getKey':
            print(cipherFun.getKey())

        elif str == 'changeKey':
            while True:
                print("Enter a valid cipher key, 'random' for a random key, or 'quit' to quit: ")
                cipher = input()

                if cipher == 'random':
                    cipherFun.setKey(makeRandomKey())
                    break
                elif cipher == 'quit':
                    break
                elif isLegalKey(cipher) == False:
                    print("Illegal key entered. Try again")
                else:
                    cipherFun.setKey(cipher)
                    print("New cipher key: ", cipherFun.getKey())
                    break
        elif str == 'encrypt':
            print("Enter a text to encrypt: ")
            str = input()
            res = cipherFun.encryptText(str)
            print("The encrypted text is: ", res)

        elif str == 'decrypt':
            print("Enter a text to decrypt: ")
            str = input()
            res = cipherFun.decryptText(str)
            print("The decrypted text is: ", res)

        elif str == 'quit':
            print("Thanks for visiting!")
            flag =1

        else:
            print("command not recognized. Try again")

main()