Python猜数字游戏遇UnboundLocalError错误，求问题原因排查

问题场景 #

编写用户与电脑对战的猜数字游戏，电脑通过random模块随机选数，用户输入数字后程序抛出UnboundLocalError，相关代码如下：

import random

player_score = 0
computer_score = 0
restart = 'Y'
stop = 'N'

print("Can you test your luck against the computer?\n Guess the number the computer is thinking, and you win!")
print("---------------------------------------------------------------------------------------------------------------------------------------")

def game():
    player_choice = int(input("Please chose a number: "))
    computer_choice = random.randint(0, 5)
    if player_choice == computer_choice:
        player_score += 1
        print("You win!\nComputer Score: ",computer_score," Player Score: ",player_score)
    elif player_choice != computer_choice:
        computer_choice += 1
        print("Computer wins...\nComputer Score: ",computer_score," Player Score: ",player_score)

错误原因 #

核心问题：变量作用域冲突 #

• player_score和computer_score是定义在函数外部的全局变量，但在game()函数内部尝试修改这些变量时，Python会默认将它们识别为局部变量。
• 当函数执行到player_score += 1或访问computer_score时，Python找不到这些变量的局部定义，直接抛出UnboundLocalError。

额外笔误 #

elif分支里写的computer_choice += 1是逻辑错误，你实际想累加的是computer_score（电脑得分），而非电脑随机选择的数字，这会导致分数统计完全失效。

修复方案 #

方案1：使用global声明全局变量 #

明确告知函数要操作的是外部全局变量：

import random

player_score = 0
computer_score = 0
restart = 'Y'
stop = 'N'

print("敢和电脑比运气吗？\n猜对电脑想的数字你就赢了！")
print("---------------------------------------------------------------------------------------------------------------------------------------")

def game():
    global player_score, computer_score  # 声明要使用的全局变量
    player_choice = int(input("请选择一个数字："))
    computer_choice = random.randint(0, 5)
    if player_choice == computer_choice:
        player_score += 1
        print(f"你赢了！\n电脑得分：{computer_score} 你的得分：{player_score}")
    else:
        computer_score += 1  # 修正笔误，累加电脑得分
        print(f"电脑赢了...\n电脑得分：{computer_score} 你的得分：{player_score}")

方案2：通过参数传递+返回值更新分数（更推荐） #

避免全局变量带来的副作用，函数接收分数参数并返回更新后的结果：

import random

player_score = 0
computer_score = 0
restart = 'Y'
stop = 'N'

print("敢和电脑比运气吗？\n猜对电脑想的数字你就赢了！")
print("---------------------------------------------------------------------------------------------------------------------------------------")

def game(p_score, c_score):
    player_choice = int(input("请选择一个数字："))
    computer_choice = random.randint(0, 5)
    if player_choice == computer_choice:
        p_score += 1
        print(f"你赢了！\n电脑得分：{c_score} 你的得分：{p_score}")
    else:
        c_score += 1
        print(f"电脑赢了...\n电脑得分：{c_score} 你的得分：{p_score}")
    return p_score, c_score

# 调用函数时更新分数
player_score, computer_score = game(player_score, computer_score)

内容的提问来源于stack exchange，提问作者AndreiDalton93