NameErorr名称'filename'从另一个函数返回'filename'后未定义

Question

[您好，我正在使用python 3为一个简单的Caesar密码解密程序编写代码，当我尝试运行该程序时收到此错误消息。这是代码，我对代码后的情况有一些描述。

def main():


        def getInputFile():
                """get the name of the file user wants to decrypt and check 
                if its extension is txt or not and return the file name"""
                filename = input('Enter the input file name: ')

                while not filename.endswith('.txt'): 
                        filename = input('Invalid file name extension. Please re-enter the input file name: ')

                return filename

        def decrypt(filename):
                """open the secret message and decrypt the caesar cipher and 
                return original message"""
                readSecretMessage = open(filename, "r")
                lines = readSecretMessage.readline()
                cipher_key = int(lines[0])
                secret_message = lines[1]
                decrypted = ""

                for letter in secret_message:
                        if letter in alphabet:
                                # decrypting
                                letter_index = (alphabet.find(letter) - cipher_key) % 26
                                decrypted = decrypted + alphabet[letter_index]
                        else:
                                decrypted = decrypted + letter

                return decrypted

        getInputFile()
        message_decrypted = decrypt(filename)
        print('The decrypted message is: ')
        print(message_decrypted)


main()

并且当我尝试运行解密功能时，我从最后第四行收到此错误消息。我认为这一切都很好，因为我从getInputFile函数返回了“ filename”值，但我猜不是。有人可以帮我弄清楚为什么它不起作用以及如何解决这个问题吗？

感谢您的时间！

Answer 1

从函数中返回名为filename的变量不会在调用该函数的范围内自动创建名为filename的变量。您需要将返回的值显式分配给变量：

f_name = getInputFile()
message_decrypted = decrypt(f_name)