在 python 上保存变量输入

Question

im trying to save an input on a list and when the function is running its checking if the letter is on the list, if it is a new guess its return True. but i dont sucess to save the guesses in the variable. thanks for help ! (im even ask from the function to print the list to show if its save the guesses but its not)

  letter_guessed = input("please guess a letter").lower()    
  old_letters_guessed = [ ]

def check_valid_input(letter_guessed, old_letters_guessed):
    """
    this function will check if the the guess is ok
    :param letter_guesses: the user's guess
    :type letter_guesses: str
    :return: True if the guess is complies with the rules and False if not
    :rtype: bool
    """
    import string 
    if letter_guessed.isalpha() and len(letter_guessed) == 1 and letter_guessed not in old_letters_guessed :
        return(True) 
    else:
        return(False) 
    old_letters_guessed.append(letter_guessed)
    print(old_letters_guessed)
    
check_valid_input(letter_guessed, old_letters_guessed)

Answer 1

You have return statement in both clauses of the if/else - the function returns before old_letters_guessed.append(... is executed. You need to move the append statement before the return statements.

Here is one way to do it.

is_valid = (letter_guessed.isalpha()) and (len(letter_guessed) == 1) and (letter_guessed not in old_letters_guessed)
if is_valid: old_letters_guessed.append(letter_guessed)
return is_valid

Answer 2

You are returning the function in the if else statement itself. Any code after the return won't work.

letter_guessed = input("please guess a letter").lower()    
old_letters_guessed = [ ]

def check_valid_input(letter_guessed, old_letters_guessed):
    """
    this function will check if the the guess is ok
    :param letter_guesses: the user's guess
    :type letter_guesses: str
    :return: True if the guess is complies with the rules and False if not
    :rtype: bool
    """
    import string 
    if letter_guessed.isalpha() and len(letter_guessed) == 1 and letter_guessed not in old_letters_guessed :
        old_letters_guessed.append(letter_guessed)
        print(old_letters_guessed)
        return(True) 
    else:
        print(old_letters_guessed)
        return(False) 
   
    
check_valid_input(letter_guessed, old_letters_guessed)

This should work.