Python之异常处理

Python之异常处理

本节重点：理解try，Exception，raise等异常报错

代码如下：

#!/usr/bin/env python

# -*- coding:utf8 -*-

# @Time     : 2017/11/8 9:39

# @Author   : hantong

# @File     : except.py

#异常是一个事件，是一个python对象，表示一个错误

#Exception 所有异常类的基类

#IndexError 超出索引范围错误

a = 5

b = 2

c = 0

try:

    a/b

    # print(a)

except Exception as e:

    print(e)

#a/b能够正常执行，所以代码不会报异常

try:

    a/c

except Exception as e:

    print(e)

#0不能为除数，所以会报错

try:

   with open('1.txt','r') as f:

       tt = f.read()

       print(tt)

except Exception as e:

      print(e)

#文件存在的时候，打开不会报异常

try:

   with open('3.txt','r') as f:

       tt = f.read()

       print(tt)

except Exception as e:

      print(e)

      raise e

finally:

      print('finally')

print('hello world!')

#当文件不存在时，打开会报异常错误

#raise关键字,捕获异常抛出，程序运行终止，但是finally还是会执行的,

#所以finally会打印出来，而hello world就不会被打印出来

执行结果：

integer division or modulo by zero

Traceback (most recent call last):

11111

222

  File "E:/Ǩ������/python/pycharm2017pjb/PycharmProjects/except.py", line 37, in <module>

ggg

    raise e

eeerr

IOError: [Errno 2] No such file or directory: '3.txt'

jjjj

[Errno 2] No such file or directory: '3.txt'

finally