Question

所以我正在开发一款游戏，这是我目前的代码，工作正常：

print("Type directions() to see commands" )

def directions() :

    print("Type North, East, South or West to move" )
    move = input("North, East, South or West? ")
    if move == "North":
    north()
    elif move == "East":
    east()
    elif move == "South":
    south()
    elif move == "West":
    west()


def north():
    print("You moved North")
    x=0
    x=(x+1) 
    print("You are at co-ordinates", x, "x:0 y" )

但是，我知道稍后会出现问题，因为x会针对每个方向重置。将x=0放在代码顶部并将其从def north()部分删除时，在运行代码时，Python会给出错误：

'UnboundLocalError：在赋值'
之前引用的局部变量'x'

我如何对此进行编码，以便'x'开头为0，但可以通过def函数进行更改？

Answer 1

您可以执行以下两项操作之一：使用全局变量（应避免使用全局变量），或使用返回值。全球方法：

x=0
.
.
def directions():
    .
    .
def north():
    global x
    x=x+1
    print("moved north...")

或者，返回值：

def directions():
    current_location = 0
    .
    .
    if move == "North":
         current_location = North(current_location)
    .
    .
def North(location):
    print("moved north...")
    return location+1

根据您的问题和y的存在来判断，您可以执行以下操作：

def directions():
.
.
    if move == "North":
        (x,y) = North(x,y)
.
.
def North(x,y):
    return (x+1,y)
def East(x,y):
    return (x,y+1)
def South(x,y):
    return (x-1,y)

Answer 2

一些提示（不详尽，但足以开始）：

首先，使用全球字典作为指示：

def north(x):
    return x+1

directions = {'North': north, 'East': east, 'South': south, 'West': west}
def move(x) :
    global directions
    print("Type North, East, South or West to move")
    move_choice = input("North, East, South or West? ")
    # modify lambda to your logic to handle incorrect inputs
    x = directions.get(move, lambda y:y)(x)
    repr(x)
    return x

如果你想要功能方法（而不是OOP），你的函数必须接受一些参数：

def north(x):
    return x+1

不要混淆你的逻辑和表示，这样你就不得不复制很多代码：

def repr(x):
    print("You are at co-ordinates {} x:0 y".format(x))

并将它们合并到main例行程序中：

def main():
    x = 0
    while True: # modify to be able to terminate this loop
        x = move(x)

Answer 3

按照Cygwinnian的建议，将x作为全局变量将解决问题。这意味着可以在使用x之前声明global x的所有函数访问相同的x变量。

修复错误：

x = 0

print("Type directions() to see commands" )

def directions() :
    print("Type North, East, South or West to move" )
    move = input("North, East, South or West? ")
    if move == "North":
    north()
    elif move == "East":
    east()
    elif move == "South":
    south()
    elif move == "West":
    west()


def north():
    global x
    print("You moved North")
    x=(x+1) 
    print("You are at co-ordinates", x, "x:0 y" )

如何正确更新'x'？

3 个答案: