Python input(): "NameError: name 'n' 未定义"
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input(): "NameError: name 'n' is not defined"
提问by Cal Courtney
Ok, so I'm writing a grade checking code in python and my code is:
好的，所以我正在用 python 编写成绩检查代码，我的代码是：
unit3Done = str(input("Have you done your Unit 3 Controlled Assessment? (Type y or n): ")).lower()
if unit3Done == "y":
pass
elif unit3Done == "n":
print "Sorry. You must have done at least one unit to calculate what you need for an A*"
else:
print "Sorry. That's not a valid answer."
When I run it through my python compiler and I choose "n", I get an error saying:
当我通过 python 编译器运行它并选择 时"n"，我收到一条错误消息：
"NameError: name 'n' is not defined"
“NameError：名称'n'未定义”
and when I choose "y"I get another NameErrorwith 'y'being the problem, but when I do something else, the code runs as normal.
当我选择"y"我再NameError有'y'是问题，但是当我做别的事情，代码运行正常。
Any help is greatly appreciated,
任何帮助是极大的赞赏，
Thank you.
谢谢你。
采纳答案by Ashwini Chaudhary
Use raw_inputin Python 2 to get a string, inputin Python 2 is equivalent to eval(raw_input).
使用raw_inputPython中2得到一个字符串，input在Python 2相当于eval(raw_input)。
>>> type(raw_input())
23
<type 'str'>
>>> type(input())
12
<type 'int'>
So, When you enter something like nin inputit thinks that you're looking for a variable named n:
因此，当您输入类似的内容时n，input它认为您正在寻找一个名为 的变量n：
>>> input()
n
Traceback (most recent call last):
File "<ipython-input-30-5c7a218085ef>", line 1, in <module>
type(input())
File "<string>", line 1, in <module>
NameError: name 'n' is not defined
raw_inputworks fine:
raw_input工作正常：
>>> raw_input()
n
'n'
help on raw_input:
帮助raw_input：
>>> print raw_input.__doc__
raw_input([prompt]) -> string
Read a string from standard input. The trailing newline is stripped.
If the user hits EOF (Unix: Ctl-D, Windows: Ctl-Z+Return), raise EOFError.
On Unix, GNU readline is used if enabled. The prompt string, if given,
is printed without a trailing newline before reading.
help on input:
帮助input：
>>> print input.__doc__
input([prompt]) -> value
Equivalent to eval(raw_input(prompt)).
回答by Martijn Pieters
You are using the input()functionon Python 2. Use raw_input()instead, or switch to Python 3.
您正在Python 2 上使用该input()函数。请raw_input()改用，或切换到 Python 3。
input()runs eval()on the input given, so entering nis interpreted as python code, looking for the nvariable. You could work around that by entering 'n'(so with quotes) but that is hardly a solution.
input()eval()在给定的输入上运行，因此输入n被解释为 python 代码，寻找n变量。您可以通过输入'n'（用引号引起来）来解决这个问题，但这几乎不是解决方案。
In Python 3, raw_input()has been renamed to input(), replacing the version from Python 2 altogether. If your materials (book, course notes, etc.) use input()in a manner that expects nto work, you probably need to switch to using Python 3 instead.
在 Python 3 中，raw_input()已重命名为input()，完全替换了 Python 2 中的版本。如果您的材料（书籍、课程笔记等）input()以预期n有效的方式使用，您可能需要改用 Python 3。
