异常处理是提高程序稳定、可靠的一个重要因素，笔者最近整理了下一常用的python异常处理方法，以及使用案例，记录在此处以便后续查阅。

功能

包括raise、try except两中常见异常处理方法，具体包括ValueError、OSError、TypeError、IndexError、KeyError、AttributeError、ZeroDivisionError、NameError、IOError等

代码

python源码如下：

#!/usr/bin/python
# -*- coding:utf-8 -*-

import math

def raise_func1(x):
    # def sqrt(x):
    if not isinstance(x, (int, float)):
        raise TypeError( 'x must be numeric ' )
    elif x < 0:
        raise ValueError( 'x cannot be negative ')
    else:
        print(math.sqrt(x))

def error_func1():
    '''
    ValueError
    '''
    while True:
        try:
            x = int(input('input x:'))
            print('x = ' + str(x))
            break
        except ValueError:
            print('Not valid input')


def error_func2():
    '''
    OSError
    ValueError
    '''
    try:
        f = open('myfile.txt')
        s = f.readline()
        i = int(s.strip())
        print('i= '+str(i))
    except OSError as err:
        print('os error: {0}'.format(err))
    except ValueError:
        print('Could not convert data to an integer.')


def error_func3(x):
    '''
    TypeError
    '''
    try:
        y = abs(x)
        print('abs({0})={1}'.format(x,y))
    except TypeError as err:
        print('type error: {0}'.format(err))


def error_func4(index):
    '''
    IndexError
    '''
    int_list = [0,1,2,3,4,5]
    try:
        value = int_list[index]
        print('int_list[{0}] = {1}'.format(index,value))
    except IndexError as err:
        print('index error: {0}'.format(err))


def error_func5(name):
    '''
    KeyError
    '''
    str_dict = {'a':1, 'b':2}
    try:
        value = str_dict[name]
        print('str_dict[{0}] = {1}'.format(name,value))
    except KeyError as err:
        print('key error: {0}'.format(err))


def error_func6():
    '''
    AttributeError
    '''
    int_list = [1,2,3]
    try:
        value = int_list.what
        value = int_list.count
        print(value)
    except AttributeError as err:
        print('attribute error: {0}'.format(err))


def error_func7(x):
    '''
    ZeroDivisionError
    '''
    try:
        y = 6 / x
        print(y)
    except ZeroDivisionError as err:
        print('ZeroDivision Error: {0}'.format(err))

    
def error_func8():
    '''
    NameError
    '''
    try:
        print(x)
    except NameError as err:
        print('Name Error: {0}'.format(err))


def error_func9(filename):
    '''
    IOError
    '''
    try:
        f = open(filename)
        f.close()
    except IOError as err:
        print('IO Error: {0}'.format(err))


def error_func10(filename):
    '''
    with Exception, catch all kinds of error!
    '''
    try:
        with open(filename,'r') as f:
            str_list = f.readlines()
            print(str_list)
    except Exception as e:
        print('different err:',e)


def error_functions():
    others = 'EOFError,KeyboardInterrupt,StopIteration,SyntaxError,SystemError'
    print('other error, including '+others)


if __name__ == '__main__':
    # raise_func1(-5)
    # error_func1()
    # error_func2()
    # error_func3(-5) #'abc'
    # error_func4(0) # 8
    # error_func5('a') # 'c'
    # error_func6()
    # error_func7(6) # 0
    # error_func8()
    error_func9('IO.txt')
    error_func10('IO.txt')
    error_functions()

通过 traceback 来输出报错的堆信息

#!/usr/bin/python3
# -*- coding:utf-8 -*-

import traceback

def get_error_info():
    try:
        a = 5 
        b = 0
        print(a/b)
    except Exception as e:
        print(e)
        print(traceback.format_exc())


if __name__== '__main__':
    get_error_info()

"""
输出结果：
division by zero
Traceback (most recent call last):
  File "/home/xg/files/code/gitlab/xgdoc/code/tmp/20221201-test-log/app.py", line 10, in get_error_info
    print(a/b)
ZeroDivisionError: division by zero
"""

说明

笔者测试系统为Ubuntu1910，Python3.7.