回文在函数内部不工作

Question

当我把下面的代码放在def中时，我得到了错误：“UnboundLocalError:局部变量'czy_to_palindrome‘在赋值之前引用”--如果没有。

不起作用：

while True:
    print("Podaj liczbe: ", end="")
    number = input()
    czy_to_palindrome = True
    def palindrome_check(number):
        for i in range(len(number)):
            if number[i] != number[len(number)- i - 1]:
                print("No, ", number, "is NOT a palindrome.")
                czy_to_palindrome = False
                break
        if czy_to_palindrome:
           print("Yes, ",number, "is a palindrome.")

    palindrome_check(number)

作品：

while True:
    print("Podaj liczbe: ", end="")
    number = input()
    czy_to_palindrome = True
    # def palindrome_check(number):
    for i in range(len(number)):
        if number[i] != number[len(number)- i - 1]:
            print("No, ", number, "is NOT a palindrome.")
            czy_to_palindrome = False
            break
    if czy_to_palindrome:
        print("Yes, ",number, "is a palindrome.")

    # palindrome_check(number)

请解释一下我不明白的功能改变。谢谢Begginer的编码。

Answer 1

正如他们在注释中所说的，只需添加一个全局变量或将变量传递给函数即可。以下是两种选择：

  while True:
        print("Podaj liczbe: ", end="")
        number = input()
        czy_to_palindrome = True
        def palindrome_check(number, czy_to_palindrome):
            for i in range(len(number)):
                if number[i] != number[len(number)- i - 1]:
                    print("No, ", number, "is NOT a palindrome.")
                    czy_to_palindrome = False
                    break
            if czy_to_palindrome:
               print("Yes, ",number, "is a palindrome.")
    
        palindrome_check(number, czy_to_palindrome)

或

while True:
    print("Podaj liczbe: ", end="")
    number = input()
    czy_to_palindrome = True
    def palindrome_check(number):
        global czy_to_palindrome
        for i in range(len(number)):
            if number[i] != number[len(number)- i - 1]:
                print("No, ", number, "is NOT a palindrome.")
                czy_to_palindrome = False
                break
        if czy_to_palindrome:
           print("Yes, ",number, "is a palindrome.")

    palindrome_check(number)

选择取决于您想要实现什么，如果变量确实是您需要在程序的其余部分中更改并保持不变的变量，则使用“全局”，否则使用use参数传递。