为什么python告诉我我的yes变量未定义？

Question

我用Python 2.7编写了这个脚本：

name=raw_input("Hi im a PC, who are you?")

print("Hi " + name + " how are you, are you good?")

answer = raw_input("")

if (answer) == yes:
    print("That's good to hear")
elif (answer) == no:
    print("Oh well")
else:
    print("Sorry, you didnt answer the question properly, Please answer with a yes or no")

这是我得到的错误：

Traceback (most recent call last):

File "C:/Python27/programs/2", line 4, in 

     if (answer) == yes:

NameError: name 'yes' is not defined

Answer 1

您没有名为yes变量，
您想要做的是将用户输入与字符串"yes"

会像这样：

if answer == "yes":
    # do stuff

答案旁边也不需要括号。

Answer 2

answer是一个字符串，您应该使用answer == "yes"

Answer 3

您需要在字符串中输入"或' yes并非"yes" ， no并非"no" 。

#if (answer) == yes:
if (answer) == "yes":

#elif (answer) == no:
elif (answer) == "no":

错误name 'yes' is not defined是因为解释器正在查找名为yes的变量，因为单词中没有"或' 。如果您输入"yes"则解释器会将answer变量的值与字符串"yes" 。