Python NameError: 名称 'now' 未定义
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NameError: name 'now' is not defined
提问by stevengfowler
From this source code:
从这个源代码：
def numVowels(string):
string = string.lower()
count = 0
for i in range(len(string)):
if string[i] == "a" or string[i] == "e" or string[i] == "i" or \
string[i] == "o" or string[i] == "u":
count += 1
return count
print ("Enter a statement: ")
strng = input()
print ("The number of vowels is: " + str(numVowels(strng)) + ".")
I am getting the following error when I run it:
当我运行它时，我收到以下错误：
Enter a statement:
now
Traceback (most recent call last):
File "C:\Users\stevengfowler\exercise.py", line 11, in <module>
strng = input()
File "<string>", line 1, in <module>
NameError: name 'now' is not defined
==================================================
采纳答案by NPE
Use raw_input()instead of input().
使用raw_input()代替input()。
In Python 2, the latter tries to eval()the input, which is what's causing the exception.
在 Python 2 中，后者尝试eval()输入，这就是导致异常的原因。
In Python 3, there is no raw_input(); input()would work just fine (it doesn't eval()).
在 Python 3 中，没有raw_input(); input()会工作得很好（它没有eval()）。
回答by Ryan Haining
use raw_input()for python2 and input()in python3. in python2, input()is the same as saying eval(raw_input())
使用raw_input()了python2和input()在python3。在python2中，input()和说的一样eval(raw_input())
if you're running this on the command line, try $python3 file.pyinstead of $python file.pyadditionally in this for i in range(len(strong)):I believe strongshould say string
如果您在命令行上运行它，请尝试$python3 file.py而不是$python file.py在此for i in range(len(strong)):我相信strong应该说string
but this code can be simplified quite a bit
但是这段代码可以简化很多
def num_vowels(string):
s = s.lower()
count = 0
for c in s: # for each character in the string (rather than indexing)
if c in ('a', 'e', 'i', 'o', 'u'):
# if the character is in the set of vowels (rather than a bunch
# of 'or's)
count += 1
return count
strng = input("Enter a statement:")
print("The number of vowels is:", num_vowels(strng), ".")
replacing the '+' with ',' means you don't have to explicitly cast the return of the function to a string
用 ',' 替换 '+' 意味着您不必将函数的返回值显式转换为字符串
if you'd prefer to use python2, change the bottom part to:
如果您更喜欢使用 python2，请将底部更改为：
strng = raw_input("Enter a statement: ")
print "The number of vowels is:", num_vowels(strng), "."
