添加整数时，变量不会更改

Question

我写了这段代码，当你选择一个蓝莓时，你的蓝莓会留在一个，我不知道为什么。我希望用户获得多个蓝莓，但它似乎停留在一个。

def blueberryfound(blueberries):
    print("        .-~~~~-.")
    print("       /  ( ( ' \ ")
    print("      | ( )   )  | ")
    print("      \ ) ' }  / /")
    print("       \,,,,,,,,/")
    leaveorpick = input("Enter P to pick or L to leave the blueberry!").lower()
    if leaveorpick == "p":
        print("")
        print("You chose to keep the berry.")
        blueberries = blueberries + 1
        print("You now have",blueberries,"blueberries.")

Answer 1

integer变量是不可变的，这意味着

def blueberryfound(val):
    val = val + 1

blueberries = 1
blueberryfound(blueberries)

不起作用。只有函数内部的val会递增，外部变量blueberries不会改变。相反，您可以这样做

def blueberryfound(val):
    return val + 1

blueberries = 1
blueberries = blueberryfound(blueberries)

或者，您可以使用面向对象的方法，其中播放器对象具有许多属性，blueberries是其中之一。然后，您的函数可以操作给定播放器实例的所有属性。

class Player(object):
    blueberries = 0

def blueberryfound(player):
    player.blueberries += 1

player = Player()
blueberryfound(player)