python - 为什么我的 Python 函数中的坐标变量没有递增和递减？

Question

我正在用 Python 编写一个基于文本的冒险游戏，玩家在 5x5 网格上移动并拾取元素，但我在更改玩家的坐标时遇到了麻烦。 coorx 和 coory 在各自的函数内不递增和递减。

coorx = 3 #The beginning x coordinate of the player
coory = 3 #The beginning y coordinate of the player

loop = True
#The dimensions of the map are 5x5.
# __ __ __ __ __
#|  |  |  |  |  |
#|__|__|__|__|__|
#|  |  |  |  |  |
#|__|__|__|__|__|
#|  |  |><|  |  |
#|__|__|__|__|__|
#|  |  |  |  |  |
#|__|__|__|__|__|
#|  |  |  |  |  |
#|__|__|__|__|__|
#>< = The player's starting position on the map

def left(coorx):
    if coorx != 1: #This checks if the x co-ordinate is not less than 1 so the player does walk off the map.
        coorx -= 1 #This function moves the player left by decrementing the x co-ordinate.

def right(coorx):
    if coorx != 5: #This checks if the x co-ordinate is not more than 5 so the player does walk off the map.
        coorx += 1 #This function moves the player right by incrementing the x co-ordinate.

def back(coory):
    if coory != 1: #This checks if the y co-ordinate is not less than 1 so the player does walk off the map.
        coory -= 1 #This function moves the player left by decrementing the y co-ordinate.

def forward(coory):
    if coory != 5: #This checks if the y co-ordinate is not more than 5 so the player does walk off the map.
        coory += 1 #This function moves the player right by incrementing the y co-ordinate.


while loop: #This loops as long as the variable "loop" is True, and since "loop" never changes, this is an infinite loop.
    move = input().lower()

    if move == "l":
        left(coorx)
        print("You move left.")
        print(coorx, coory)
    elif move == "r":
        right(coorx)
        print("You move right.")
        print(coorx, coory)
    elif move == "f":
        forward(coory)
        print("You move forward.")
        print(coorx, coory)
    elif move == "b":
        back(coory)
        print("You move backwards.")
        print(coorx, coory)

这就是输出的内容。

>f
>You move forward.
>3 3
>f
>You move forward.
>3 3
>l
>You move left.
>3 3
>l
>You move left.
>3 3
>b
>You move backwards.
>3 3
>b
>You move backwards.
>3 3
>r
>You move right.
>3 3
>r
>You move right.
>3 3

正如您所看到的，坐标始终从“3 3”不变。任何对我的问题的帮助将不胜感激。

Answer 1

您的坐标是全局，但您尚未将它们声明为全局坐标，因此它们被同名的局部变量所遮蔽。您需要使用函数将它们声明为全局，以便能够修改它们。

选项一(无全局变量):

def left(x_coord):
    if x_coord != 1: 
        x_coord -= 1
    return x_coord # Do something with this

选项二:

def left():
    global coorx
    if coorx != 1:
        coorx -= 1

您可以阅读有关全局变量的更多信息 here和 here