python2.7以下出 NameError: global name 'FileNotFoundError' is not defined的解决方案

原文链接：http://blog.csdn.net/waiwai3/article/details/77461276

处理文件不存在使用FileNotFoundError来处理异常

Python版本：2.6

python代码：

[python]
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def count_words(filename):

        try:

                with open(filename) as f_obj:

                        contents = f_obj.read()

        except FileNotFoundError:

                msg = "Sorry, the file " + filename + " does not exist."

                print(msg)

        else:

                words = contents.split()

                num_words = len(words)

                print("The file " + filename + " has about " + str(num_words) +" words.")

filename = 'alice.txt'

count_words(filename

运行结果：

[python]
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Traceback (most recent call last):

  File "./count_words.py", line 15, in <module>

    count_words(filename)

  File "./count_words.py", line 6, in count_words

    except FileNotFoundError:

NameError: global name 'FileNotFoundError' is not define

报错原因：

FileNotFoundError为python3使用的文本不存在异常处理方法

在python2.7中使用IOError

修改后的python代码

[python]
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#!/usr/bin/env python

def count_words(filename):

        try:

                with open(filename) as f_obj:

                        contents = f_obj.read()

        #except FileNotFoundError:

        except IOError:

                msg = "Sorry, the file " + filename + " does not exist."

                print(msg)

        else:

                words = contents.split()

                num_words = len(words)

                print("The file " + filename + " has about " + str(num_words) +" words.")

filename = 'alice.txt'

count_words(filename)

运行结果：

[python]
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Sorry, the file alice.txt does not exist