为什么 none 类型会给出 int 错误？删除时说索引必须是 int 而不是 str

Question

我正在制作一款基于房间的文字冒险游戏。如果您运行代码，如果您进入房间边界（即从卧室 2 开始，然后到卧室 1，反之亦然），它会起作用，但是一旦您走出边界，就会出现错误：

>>> print(room_list[int(current_room)][0])
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

删除int() 后，我得到一个不同的错误：

TypeError: list indices must be integers or slices, not str

如何修复它以保留 None 类型？或者只是让代码工作。下面是我的代码。

def main():
    done = False
    room_list = []
    current_room = 0

    # Append rooms to different numbers
    room = ["\nYou are in bedroom 2.\nThere is a passage north and east.", "3", "1", None, None]  # Room name, N, E S, W
    room_list.append(room)

    room = ["\nYou are in at southern hall.\nThere is a passage  north and east.", "4", "2", None, "0"]
    room_list.append(room)

    room = ["\nYou are in the dining room.\nThere is a passage north and west.", "5", None, None, "1"]
    room_list.append(room)

    room = ["\nYou are in bedroom 1.\nThere is a passage east and south.", None, "4", "0", None]
    room_list.append(room)

    while not done:
        print(room_list[int(current_room)][0])
        answer = input('What direction? ')

        # Check for correct direction and check if exists
        if answer == "n":
            next_room = room_list[int(current_room)][1]
            current_room = next_room
            if next_room == None:
                print("You can't go that way. ")

        elif answer == "e":
            next_room = room_list[int(current_room)][2]
            current_room = next_room
            if next_room == None:
                print("You can't go that way. ")

        elif answer == "s":
            next_room = room_list[int(current_room)][3]
            current_room = next_room
            if next_room == None:
                print("You can't go that way. ")

        elif answer == "w":
            next_room = room_list[int(current_room)][4]
            current_room = next_room
            if next_room == None:
                print("You can't go that way. ")

        elif answer == "q":
            done = True

        else:
            print("Invalid destination, try again.")

main()

Answer 1

好吧，因为current_room（或next_room）是None...你应该在if语句之后移动current_room = next_room，在else子句下

def main():
    done = False
    room_list = []
    current_room = 0

    # Append rooms to different numbers
    room = ["\nYou are in bedroom 2.\nThere is a passage north and east.", "3", "1", None, None]  # Room name, N, E S, W
    room_list.append(room)

    room = ["\nYou are in at southern hall.\nThere is a passage  north and east.", "4", "2", None, "0"]
    room_list.append(room)

    room = ["\nYou are in the dining room.\nThere is a passage north and west.", "5", None, None, "1"]
    room_list.append(room)

    room = ["\nYou are in bedroom 1.\nThere is a passage east and south.", None, "4", "0", None]
    room_list.append(room)

    while not done:
        print(room_list[int(current_room)][0])
        answer = input('What direction? ')

        # Check for correct direction and check if exists
        if answer == "n":
            next_room = room_list[int(current_room)][1]
            if next_room is None: # == None can be replaced with is None
                print("You can't go that way. ")
            else:
                current_room = next_room

        elif answer == "e":
            next_room = room_list[int(current_room)][2]
            if next_room is None:
                print("You can't go that way. ")
            else:
                current_room = next_room

        elif answer == "s":
            next_room = room_list[int(current_room)][3]
            if next_room is None:
                print("You can't go that way. ")
            else:
                current_room = next_room

        elif answer == "w":
            next_room = room_list[int(current_room)][4]
            if next_room is None:
                print("You can't go that way. ")
            else:
                current_room = next_room

        elif answer == "q":
            done = True

        else:
            print("Invalid destination, try again.")

main()