Palindrome doesn't work inside of a function

Question

I got error of below code while placed in def : " UnboundLocalError: local variable ‘czy_to_palindrome’ referenced before assignment"
It works fine without.

DOES NOT WORK:

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)

WORKS:

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)

Explain please what function change I do not understand. Thanks
Begginer in codeing.

Asked By: Micheal_new

||

Source

Answer 1

As they say in the comments, just add a global variable or pass the variable to the function. Here are the two options:

  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)

Or

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)

The choice depends on what you want to achieve, if the variable is really a variable that you need to change in the rest of the program and stay that way, use ‘global’ otherwise use parameter passing.

Answered By: FG94

Palindrome doesn't work inside of a function

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