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

原文鏈接：http://blog.csdn.net/waiwai3/article/details/77461276

處理文件不存在使用FileNotFoundError來處理異常

Python版本：2.6

python代碼：

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

運行結果：

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

報錯原因：

FileNotFoundError爲python3使用的文本不存在異常處理方法

在python2.7中使用IOError

修改後的python代碼

#!/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)

運行結果：

Sorry, the file alice.txt does not exist