Python井字棋游戏check_winner函数为何不打印获胜提示？

问题描述 #

我正在用Python开发一款井字棋游戏，目前功能可用但尚未完善。问题在于编写的check_winner函数在检测到获胜情况时，return True语句后的获胜提示信息无法打印。

原check_winner函数代码：

def check_winner(spots):
        if spots[1] == spots[2] == spots[3]:
            return True
            print("Winner found!")
        if spots[4] == spots[5] == spots[6]:
            return True
            print("Winner found!")
        if spots[7] == spots[8] == spots[9]:
            return True
            print("Winner found!")
        if spots[1] == spots[4] == spots[7]:
            return True
            print("Winner found!")
        if spots[3] == spots[6] == spots[9]:
            return True
            print("Winner found!")
        if spots[1] == spots[5] == spots[9]:
            return True
            print("Diagonal winner found!")
        if spots[3] == spots[5] == spots[7]:
            return True
            print("Diagonal winner found!")

游戏主循环代码：

while winner == False:
    if Turns % 2:
        Letter = 'X'
    else:
        Letter = 'O'
    print_board(spots)
    if check_winner(spots) == True:
        break

当棋盘检测到获胜者，函数返回True时，获胜提示完全不打印，请问这是为什么？

问题原因 #

return语句会立即终止函数的执行流程，一旦函数执行到return True，会直接跳出函数返回结果，后面的print语句根本没有机会被执行。这就是提示信息无法打印的核心原因。

修复方案 #

方案1：将print语句移到return之前 #

调整函数内代码顺序，先打印提示再返回结果：

def check_winner(spots):
        if spots[1] == spots[2] == spots[3]:
            print("Winner found!")
            return True
        if spots[4] == spots[5] == spots[6]:
            print("Winner found!")
            return True
        if spots[7] == spots[8] == spots[9]:
            print("Winner found!")
            return True
        if spots[1] == spots[4] == spots[7]:
            print("Winner found!")
            return True
        if spots[3] == spots[6] == spots[9]:
            print("Winner found!")
            return True
        if spots[1] == spots[5] == spots[9]:
            print("Diagonal winner found!")
            return True
        if spots[3] == spots[5] == spots[7]:
            print("Diagonal winner found!")
            return True
        return False  # 没有获胜情况时返回False，避免函数无返回值

方案2：让函数返回获胜类型，在主循环中打印提示 #

这种方式更符合单一职责原则，函数只负责检测获胜并返回结果，打印逻辑放在主循环里：

def check_winner(spots):
        if spots[1] == spots[2] == spots[3]:
            return "horizontal"
        if spots[4] == spots[5] == spots[6]:
            return "horizontal"
        if spots[7] == spots[8] == spots[9]:
            return "horizontal"
        if spots[1] == spots[4] == spots[7]:
            return "vertical"
        if spots[3] == spots[6] == spots[9]:
            return "vertical"
        if spots[1] == spots[5] == spots[9]:
            return "diagonal"
        if spots[3] == spots[5] == spots[7]:
            return "diagonal"
        return None  # 无获胜时返回None

# 修改主循环
while winner == False:
    if Turns % 2:
        Letter = 'X'
    else:
        Letter = 'O'
    print_board(spots)
    result = check_winner(spots)
    if result:
        if result in ["horizontal", "vertical"]:
            print("Winner found!")
        else:
            print("Diagonal winner found!")
        break

内容的提问来源于stack exchange，提问作者rooknoobski