IndexError：python中的列表索引超出范围错误

Question

我正在为个人项目编写vigenere密码，并且遇到索引错误。它说的是IndexError: list index out of range。 造成这种情况的线路是IndexValue = Alphabet.index(keyList[keyIncrement]) + Alphabet.index(plainTextChar)。

这里是所有的代码：

playing = True 
string = "" 
Alphabet = ('z','a','b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z') 

while playing == True: 
    string = "" 
    eord = input('Type "d" to "decrypt" and "e" to "encrypt": ') 

    if eord == 'e': 
     texte = input ("Type your word to encrypt: ") 
     key1 = int(input("Choose a key between 1-26: ")) 
     for letter in texte: 
      number = (ord(letter)) + (key1) 
      letter=(chr(number)) 
      string = (str(string)) + (str(letter)) 
     print (string) 
     keyword = input ("Type 'encrypt' code further or 'decrypt' further: ") 

     if keyword == 'encrypt': 
      plainText = input("Please enter the plain text: ") 
      key = input("Please enter the key: ") 
      keyList = [] 
      keyLength = 0 
      while keyLength < len(plainText): 
       for char in key: 
        if keyLength < len(plainText): 
         keyList.append(str(char)) 
         keyLength = keyLength + 1 
         CipherText = [] 
         IndexValue = 0 
         keyIncrement = 0 
        for plainTextChar in plainText: 
         IndexValue = Alphabet.index(keyList[keyIncrement]) + Alphabet.index(plainTextChar) 
         while IndexValue > 26: 
          IndexValue = IndexValue - 26 
         CipherText.append(Alphabet[IndexValue]) 
         keyIncrement = keyIncrement + 1 
         print (''.join(CipherText)) 

      finish = input('Would you like to go again Y or N') 
      if finish == 'n' or finish == 'N': 
       retry = input ("Would you like to go again? Y or N: ") 
       if retry == 'N' or retry == 'n': 
        print ("Please exit the window") 
        import time 
        time.sleep(1) 
        import sys 
        sys.exit() 

    elif eord == 'd': 
     texd = input ("Type your word to decrypt: ") 
     key2 = int(input("Choose a key between 1-16: ")) 

     for letter in texd: 
      number = (ord(letter)) - (key2) 
      letter=(chr(number)) 
      string = (str(string)) + (str(letter)) 
     print (string) 
     keyword = input ("Type 'encrypt' code further or 'decrypt' further: ") 

     if keyword == 'decrypt': 
      plainText = input("Please enter the plain text: ") 
      key = input("Please enter the key: ") 
      keyList = [] 
      keyLength = 0 
      while keyLength < len(plainText): 
       for char in key: 
        if keyLength < len(plainText): 
         keyList.append(str(char)) 
         keyLength = keyLength - 1 
         completeCipherText = [] 
         cipherCharIndexValue = 0 
         keyIncrement = 0 
        for plainTextChar in plainText: 
         cipherCharIndexValue = Alphabet.index(keyList[keyIncrement]) + Alphabet.index(plainTextChar) 
         while cipherCharIndexValue > 26: 
          cipherCharIndexValue = cipherCharIndexValue + 26 
         completeCipherText.append(Alphabet[cipherCharIndexValue]) 
         keyIncrement = keyIncrement - 1 
         print (''.join(completeCipherText)) 

         finish = input('Would you like to go again Y or N') 
         if finish == 'n' or finish == 'N': 
          retry = input ("Would you like to go again? Y or N: ") 
          if retry == 'N' or retry == 'n': 
           print ("Please exit the window") 
           import time 
           time.sleep(1) 
           import sys 
           sys.exit() 

它正在发生的部分是这样的：

if keyword == 'encrypt': 
      plainText = input("Please enter the plain text: ") 
      key = input("Please enter the key: ") 
      keyList = [] 
      keyLength = 0 
      while keyLength < len(plainText): 
       for char in key: 
        if keyLength < len(plainText): 
         keyList.append(str(char)) 
         keyLength = keyLength + 1 
         CipherText = [] 
         IndexValue = 0 
         keyIncrement = 0 
        for plainTextChar in plainText: 
         IndexValue = Alphabet.index(keyList[keyIncrement]) + Alphabet.index(plainTextChar) 
         while IndexValue > 26: 
          IndexValue = IndexValue - 26 
         CipherText.append(Alphabet[IndexValue]) 
         keyIncrement = keyIncrement + 1 
         print (''.join(CipherText)) 

什么是错的代码，因为我尝试使用pycharm并强调[keyIncrement]，但我不知道如何解决这个问题。感谢您提前提供任何帮助。

Answer 1

你的问题是这个if keyLength < len(plainText):语句阻止for character in key在运行其余代码之前将每个字符添加到列表中。

while keyLength < len(plainText): 
    try: 
     char = key[num] 
    except IndexError: 
     num = 0 
     char = key[num] 
    keyList.append(str(char)) 
    keyLength += 1 
    num += 1 
    CipherText = [] 
    IndexValue = 0 
    keyIncrement = 0 
for plainTextChar in plainText: 
    IndexValue = Alphabet.index(keyList[keyIncrement]) + Alphabet.index(plainTextChar) 
    while IndexValue > 26: 
     IndexValue = IndexValue - 26 
    CipherText.append(Alphabet[IndexValue]) 
    keyIncrement = keyIncrement + 1 
    print (''.join(CipherText)) 

试运行：

Type "d" to "decrypt" and "e" to "encrypt": e 
Type your word to encrypt: hello 
Choose a key between 1-26: 3 
khoor 
Type 'encrypt' code further or 'decrypt' further: encrypt 
Please enter the plain text: darrien 
Please enter the key: brit 
f 
fs 
fsa 
fsal 
fsalk 
fsalkw 
fsalkww 
Would you like to go again Y or N