尝试从函数分配时全局变量不起作用

Question

我正在学习 Python，但我遇到了 gobal 变量的问题。我已经在全局范围内定义了变量，然后使用 global 关键字从函数中分配它们。但是，当它运行脚本时，它仍然无法分配变量。

看了这个解决方案，Using global variables in a function，我不知道为什么他的代码可以正常工作，而我的相同逻辑却失败了。几个小时都想不通并陷入小问题。

def player_input():
    player_1_name = input('Please enter your name Player 1.')
    player_2_name = input('Please enter your name Player 2.')
    player_1_symbol='None'
    player_2_symbol=''
    allowed_symbol=['X','O']
    symbol_accepted = False

def get_symbol():
    global player_1_symbol
    player_1_symbol = input('Please enter your preferred symbol {}. It can be either X or O.   '.format(player_1_name))
    print('value of symbol after assignment: '+ player_1_symbol)

def validate_symbol():
    global symbol_accepted
    print('value of symbol when process started: '+ player_1_symbol)
    if player_1_symbol.upper() in allowed_symbol:
        print('it passed')
        symbol_accepted = True
    else:
        print('it came here, because it did not find the value of player_1_symbol')
        get_symbol()

while symbol_accepted == False:
    validate_symbol()

if player_1_symbol.upper() == 'O':
    player_2_symbol = 'X'
else:
    player_2_symbol = 'O'

print("{}, unfortunately you don't have choice. You have been assigned the symbol {}.".format(player_2_name,player_2_symbol))

我想要达到的结果是我想 assign player_1_symbol 从 get_symbol 函数到全局变量。 symbol_accepted 也是如此。没有变量被分配。我正在打印它们，但我无法理解为什么它不起作用。我在 youtube 上看到了一些视频和一些文章。

我看到了一些关于输入验证的其他视频/文章，但是一旦我开始这个，我想了解它有什么问题，以便我将来可以使用 global。

Answer 1

我用 player_symbols 创建了一个数组（player_1 为 0，player_2 为 1），因此可以正确分配变量。我还修复了 validate_symbol 重复的错误，因为 symbol_accepted 有相同的错误。

def player_input():
    player_1_name = input('Please enter your name Player 1.')
    player_2_name = input('Please enter your name Player 2.')
    player_symbols = ["", ""]
    allowed_symbol = ['X', 'O']
    symbol_accepted = False

    def get_symbol():
        player_symbols[0] = input(
            'Please enter your preferred symbol {}. It can be either X or O.   '.format(player_1_name))
        print('value of symbol after assignment: ' + player_symbols[0])

    def validate_symbol(symbol_accepted):
        print('value of symbol when process started: ' + player_symbols[0])
        if player_symbols[0].upper() in allowed_symbol:
            print('it passed')
            symbol_accepted = True
        else:
            print('it came here, because it did not find the value of player_1_symbol')
            get_symbol()
        return symbol_accepted

    while symbol_accepted == False:
        symbol_accepted = validate_symbol(symbol_accepted)

    if player_symbols[0].upper() == 'O':
        player_symbols[1] = 'X'
    else:
        player_symbols[1] = 'O'

    print("{}, unfortunately you don't have choice. You have been assigned the symbol {}.".format(player_2_name,
                                                                                                  player_symbols[1]))
player_input()