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代码：

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：

Traceback (most recent call last):

File "./count_words.py", line 15, in

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

#!/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：

Sorry, the file alice.txt does not exist