赋值前引用的全局变量？

Question

我是 Python 的新手，我正在尝试创建一个非常简单的代码，每次用户按下 Enter 键时，他们都会获得 5 分，然后是打印他们当前拥有多少分的行。 代码如下所示：

pointsEarned = 0
alien_0 = {"points":5}
new_points = alien_0["points"]
def kill():
    input("Press enter to kill an alien!")
    pointsEarned = pointsEarned + 5
    killed()
def killed():
    print("You just earned " + str(new_points) + " points!")
    print("Current points: " + str(pointsEarned))
    kill()
kill()

但是，当我运行此代码时，它给了我这个错误：

UnboundLocalError: local variable 'pointsEarned' referenced before assignment

我不明白这一点，因为我事先在任一函数之外定义了 pointsEarned。 我该如何解决？

Answer 1

pointsEarned = 0
alien_0 = {"points":5}
new_points = alien_0["points"]
def kill():
    global pointsEarned 
    input("Press enter to kill an alien!") 
    pointsEarned += 5
    killed()
def killed():
    print("You just earned " + str(new_points) + " points!")
    print("Current points: " + str(pointsEarned))
    kill()
kill()