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#!/usr/bin/env python3

# -*- coding: utf-8 -*-

'练习错误处理'

__author__ = 'sergiojune'

import logging

from functools import reduce

def foo(n):

# 自定义抛出错误

if n == 0:

raise ZeroDivisionError('被除数不能为零')

return 10 / n

print(foo(20))

# 这个就会出错

# print(foo(0))

# 捕捉错误

try:

n = input('请输入一个数字')

n = int(n)

res = 10 / n

print(res)

# 有多种异常情况，所以有多个except语句块

except ZeroDivisionError as e:

print(e)

except ValueError as e:

# 用这个记录错误，开发中会发在日志上查看

logging.exception(e)

# 当没有发生错误时会执行

else:

print('成功运行')

# 这个语句块是必须执行的

finally:

print('代码执行完毕')

print('end')

# 还可以自己创建异常

# 只需要继承自某一个异常就可以了，不过一般不需要自定义异常

class FooException(BaseException):

pass

# 作业：运行下面的代码，根据异常信息进行分析，定位出错误源头，并修复

def str2num(s):

try:

return int(s)

except ValueError as e:

logging.exception(e)

print('捕捉成功')

try:

return float(s)

except ValueError as e:

print(e)

print('输入的内容不是数字')

def calc(exp):

try:

ss = exp.split('+')

ns = map(str2num, ss)

return reduce(lambda acc, x: acc + x, ns)

except TypeError as e:

print(e)

def main():

r = calc('100 + 200 + 345')

print('100 + 200 + 345 =', r)

r = calc('99 + 88 + 7.6')

print('99 + 88 + 7.6 =', r)

main()

print('end')