Python 名称错误 : name 'north' is not defined for Text Game

Question

我为基于文本的游戏编写了此代码，但收到一条错误消息

 line 1, in <module>
userInput = input("Please enter a direction in which to travel: ")
 File "<string>", line 1, in <module>
NameError: name 'north' is not defined

这是我的代码

userInput = input("Please enter a direction in which to travel: ")
Map = {
    'north':'that way leads to the kitchen', 
    'south':'that way leads to the dining room', 
    'east':'that way leads to the entry', 
    'west':'that way leads to the living room'
}
if userInput == north:
    print Map['north']
elif userInput == south:
    print Map['south']
elif userInput == east:
    print Map['east']
elif userInput == West:
    print Map['west']
elif userInput == '':
    print "Please specify a various direction."
else:
    quit

感谢您的帮助

Answer 1

这一行

if userInput == north:
    ...

询问名为userInput的变量是否与变量north相同。

但是您还没有定义名为north的变量。该行应该与字符串 'north' 进行比较，如下所示。

if userInput == 'north':
    ...

但是，您可以像这样测试字典键中的用户输入。我已将您的常量更改为全部大写。

MAP = {
    'north':'that way leads to the kitchen', 
    'south':'that way leads to the dining room', 
    'east':'that way leads to the entry', 
    'west':'that way leads to the living room'
}
userInput = raw_input("Please enter a direction in which to travel: ")
if userInput in MAP.keys():
    print MAP[userInput]

此外，正如另一个答案中提到的，raw_input比input更安全。

另一种方法是像这样捕获 KeyError。

MAP = {
    'north':'that way leads to the kitchen', 
    'south':'that way leads to the dining room', 
    'east':'that way leads to the entry', 
    'west':'that way leads to the living room'
}
userInput = raw_input("Please enter a direction in which to travel: ")
try:
    print MAP[userInput]
except KeyError:
    print 'What?'

或重复直到提供有效的输入，如下所示(并使其不区分大小写):

MAP = {
    'north':'that way leads to the kitchen', 
    'south':'that way leads to the dining room', 
    'east':'that way leads to the entry', 
    'west':'that way leads to the living room'
}
while True:
    userInput = raw_input("Please enter a direction in which to travel: ").lower()
    try:
        print MAP[userInput]
        break
    except KeyError:
        print '%s is not an option' % userInput