zoukankan      html  css  js  c++  java
  • python try except 出现异常时,except 中如何返回异常的信息字符串

    https://docs.python.org/3/tutorial/errors.html#handling-exceptions

    https://docs.python.org/3/library/exceptions.html#ValueError

    try:
        int("x")
    except Exception as e:
        '''异常的父类,可以捕获所有的异常'''
        print(e)
    # e变量是Exception类型的实例,支持__str__()方法,可以直接打印。 
    invalid literal for int() with base 10: 'x'
    try:
        int("x")
    except Exception as e:
        '''异常的父类,可以捕获所有的异常'''
        print(e.args)
    # e变量有个属性是.args,它是错误信息的元组。

    ("invalid literal for int() with base 10: 'x'",)try: datetime(2017,2,30)except ValueError as e: print(e) day is out of range for monthtry: datetime(22017,2,30)except ValueError as e: print(e) year 22017 is out of rangetry: datetime(2017,22,30)except ValueError as e: print(e) month must be in 1..12e = Nonetry: datetime(2017,22,30)except ValueError as e: print(e) month must be in 1..12e
    # e这个变量在异常过程结束后即被释放,再调用也无效
     Traceback (most recent call last): File "<input>", line 1, in <module>NameError: name 'e' is not defined

    errarg = None
    try:
        datetime(2017,22,30)
    except ValueError as errarg:
        print(errarg)
        
    month must be in 1..12
    errarg
    Traceback (most recent call last):
      File "<input>", line 1, in <module>
    NameError: name 'errarg' is not defined
    try:
        datetime(2017,22,30)
    except ValueError as errarg:
        print(errarg.args)

    # ValueError.args 返回元组

    ('month must be in 1..12',)
    message = None
    try:
        datetime(2017,22,30)
    except ValueError as errarg:
        print(errarg.args)
        message = errarg.args
        
    ('month must be in 1..12',)
    message
    ('month must be in 1..12',)
    try:
        datetime(2017,22,30)
    except ValueError as errarg:
        print(errarg.args)
        message = errarg
        
    ('month must be in 1..12',)
    message
    ValueError('month must be in 1..12',)
    str(message)
    'month must be in 1..12'

    分析异常信息,并根据异常信息的提示做出相应处理:

    try:
        y = 2017
        m = 22
        d = 30
        datetime(y,m,d)
    except ValueError as errarg:
        print(errarg.args)
        message = errarg
        m = re.search(u"month", str(message))
        if m:
            dt = datetime(y,1,d)
            
    ('month must be in 1..12',)
    dt
    datetime.datetime(2017, 1, 30, 0, 0)

    甚至可以再except中进行递归调用:

    def validatedate(y, mo, d):
        dt = None
        try:
            dt = datetime(y, mo, d)
        except ValueError as e:
            print(e.args)
            print(str(y)+str(mo)+str(d))
            message = e
            ma = re.search(u"^(year)|(month)|(day)", str(message))
            ymd = ma.groups()
            if ymd[0]:
                dt = validatedate(datetime.now().year, mo, d)
            if ymd[1]:
                dt = validatedate(y, datetime.now().month, d)
            if ymd[2]:
                dt = validatedate(y, mo, datetime.now().day)
        finally:
            return dt
        
    validatedate(20199, 16, 33)
    ('year 20199 is out of range',)
    201991633
    ('month must be in 1..12',)
    20181633
    ('day is out of range for month',)
    2018433
    datetime.datetime(2018, 4, 20, 0, 0)
  • 相关阅读:
    seaborn---样式控制/调色板
    matplotlib---插值画二维、三维图
    25.推荐---协同过滤(Collaborative Filtering)
    PageRank
    词向量---LSA(Latent Semantic Analysis)
    深入理解Java 8 Lambda
    理解java的 多态
    Java命名规范
    Java语言中几个常用的包
    java中的类、成员变量、方法的修饰符。
  • 原文地址:https://www.cnblogs.com/wpcnblog/p/11356475.html
Copyright © 2011-2022 走看看