“NameError：名稱未定義”是什么意思？

Question

所以我一直在研究我的文本加密和解密程序，但我被卡住了。 這是我到目前為止：

  import random
  def fileopen():
       filename=input("What is the file you need to encrypt:")
       print(filename)
       with open(filename) as wordfile:
             contents=wordfile.read()
       return contents
 def Create8():
      numlist=[]
      charlist=[]
      for i in range (8):
           num=random.randint(33,126)
           numlist.append(num)
 for i in numlist:
      char = chr(i)
      charlist.append(char)
      return charlist
 def offset(key):
  store=[]
  for i in key:
        num=ord(i)
        store.append(num)
  total=sum(store)
  oFactor=((total//8)-32)

  return oFactor



  while True:
       print ("Hello, welcome to the encryption/decryption program")
       print ("1 - Encryption")
       print ("2 - Decryption")
       print ("3 - Exit")
       choice=input ("Enter a Number")

  if choice=="1":
       print("Encryption Selected")

       contents=fileopen()
       print(contents)

       Characterkey=Create8()

        OF=offset(Characterkey)

        print ("The offset factor is:")
        print (OF)

        Etext=[]
        for i in contents:
            if i ==" ":
                Etext.append(i)
            else:
                code=ord(i)
                code=code+OF
                if code >126:
                    code=code-94
                char=chr(code)
                Etext.append(char)
        print(Etext)
        encryptedtext=(''.join(Etext))
        print(''.join(Etext))

        filename=input ("What is your file going to be called")

        with open(filename,"w")as f:
              f.write(encryptedtext)

        continue


        def decrypt():
              file = input("""Please enter the name of your text file to be decrypted:
             """)
        if not file.endswith('.txt'):
              file+='.txt'
        try:
              with open (file, 'r') as file:
                    texts= file.read()
        except IOError:
              print("Error- please try again")


  character_key= input ("\nPlease enter the EXACT eight character key that was used to encrypt the message: ")

  offsetfactor_decrypt = sum(map(ord, character_key))//8-32
  result =  ''
  for letter in text:
              if letter == " ":
                    result += " "
  else:
        n = ord(letter) - offsetfactor_decrypt
        if n <33:
              n = n+ 94
              result = result + chr(n)

  print ("\nHere is your decrypted text: \n",result,)

我遇到的問題是每次運行時都會顯示：

Traceback (most recent call last):
  File "C:\Users\Callum Bowyer\Desktop\Text Encryption\Project2.py", line 105, in <module>
    for letter in text:
NameError: name 'text' is not defined

Answer 1

你的代碼寫得很糟糕，效率很低，縮進也很糟糕（python中的縮進非常重要，如果你的代碼沒有正確縮進，你會得到語法錯誤並且無法執行該代碼，請參閱http://www.python-course .eu/python3_blocks.php ）。 所以我試圖盡可能地修復你的代碼：

• 首先要運行你的代碼，我需要修復孔程序中的縮進，
• 然后我在操作符（+、-、=...符號）周圍加上空格，你的程序可以在沒有這個的情況下工作，但它更容易閱讀並嘗試理解寫得很好的代碼，

• 之后，我運行了您的代碼並試圖找出問題出在哪里，這些是我在您的代碼中更改的內容：

  • 你已經用過

    if not file.endswith('.txt'): file += '.txt'`

    檢查要解密的文本文件的名稱是否具有“.txt”擴展名，因此我添加了相同的代碼來檢查要加密的文本文件的名稱和保存加密文本的文本文件的名稱是否具有“.txt”擴展名,

  • 執行if choice == "1":的 after 代碼塊if choice == "1":我添加了elif choice == "2":並將decrypt()函數中的所有代碼放在該elif語句之后，

  • 我添加了另一個elif語句

    elif choice == "3": break

    所以當用戶輸入3程序停止執行時，

  • 您的函數Create8()和offset(key)無效，首先在函數Create8()創建numlist ，然后從中創建charlist並從函數Create8() return charlist ，然后調用函數offset(key) where 參數key在charlist從函數返回Create8()在功能offset(key)創建store這是相同的numlist從功能Create8()這樣使你的代碼有效我合並功能Create8()和offset(key) ，以一種功能Create8_and_offset()

     def Create8_and_offset(): charlist=[] total = 0 for i in range(8): num = random.randint(33,126) total += num char = chr(num) charlist.append(char) oFactor = (total//8 - 32) return charlist, oFactor

  • 最后，為什么你的代碼引起的原因NameError是（ Nullman ， nexus66和zaph在評論中提到它），與其不存在的變量text ，你使用你應該使用可變texts ，你應該這樣做：

     for letter in texts:

    而不是這個：

     for letter in text:

有效的完整（固定）代碼：

import random


def fileopen():
    filename = input("What is the file you need to encrypt: ")
    if not filename.endswith('.txt'):       # this was added to check
        filename += '.txt'                  # that file has .txt extension
    print(filename)
    with open(filename) as wordfile:
        contents = wordfile.read()
    return contents


def Create8_and_offset():
    charlist=[]
    total = 0
    for i in range(8):
        num = random.randint(33,126)
        total += num
        char = chr(num)
        charlist.append(char)
    oFactor = (total//8 - 32)
    return charlist, oFactor


##def Create8():
##    numlist=[]
##    charlist=[]
##    for i in range (8):
##        num=random.randint(33,126)
##        numlist.append(num)
##    for i in numlist:
##        char = chr(i)
##        charlist.append(char)
##    return charlist
##
##def offset(key):
##    store=[]
##    for i in key:
##        num=ord(i)
##        store.append(num)
##    total=sum(store)
##    oFactor=((total//8)-32)
##    return oFactor



while True:
    print("Hello, welcome to the encryption/decryption program")
    print("1 - Encryption")
    print("2 - Decryption")
    print("3 - Exit")
    choice = input("Enter a Number: ")

    if choice == "1":
        print("Encryption Selected")
        contents = fileopen()
        print(contents)
        #Characterkey = Create8()
        #OF = offset(Characterkey)
        Characterkey, OF = Create8_and_offset()
        print("The Characterkey is:\n" + ''.join(Characterkey))
        print("The offset factor is:")
        print(OF)

        Etext=[]
        for i in contents:
            if i == " ":
                Etext.append(i)
            else:
                code = ord(i)
                code = code + OF
                if code > 126:
                    code = code - 94
                char = chr(code)
                Etext.append(char)
        print(Etext)
        encryptedtext = (''.join(Etext))
        print(encryptedtext)

        filename = input("What is your file going to be called: ")
        if not filename.endswith('.txt'):       # this was added to check
            filename += '.txt'                  # that file has .txt extension

        with open(filename,"w")as f:
            f.write(encryptedtext)

        #continue

    elif choice == "2":

    #def decrypt():
        file = input("Please enter the name of your text file to be decrypted:\n")
        if not file.endswith('.txt'):
            file += '.txt'
        try:
            with open (file, 'r') as file:
                texts = file.read()
        except IOError:
            print("Error- please try again")


        character_key = input("\nPlease enter the EXACT eight character key that was used to encrypt the message: ")

        offsetfactor_decrypt = sum(map(ord, character_key))//8-32
        result =  ''
        #for letter in text:
        for letter in texts:
            if letter == " ":
            result += " "
            else:
                n = ord(letter) - offsetfactor_decrypt
                if n < 33:
                    n = n + 94
                result += chr(n)

        print ("\nHere is your decrypted text: \n", result)

    elif choice == "3":
        break

Answer 2

我的建議是閱讀 python 介紹 pdf。 你的代碼有各種各樣的錯誤。 學習python基礎知識會對你有很大幫助。 嘗試了解更多的函數和循環。