python异常处理,try,expect,else,finally,raise

异常处理

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.1常见的异常

下面这些都是类型class

严谨的程序应主动捕获并且处理这些异常

.2例子

在python中可以使用try except else finally raise等关键字来处理异常，使用方法如下：

异常类	执行的功能
try	后面跟着需要执行的语句
except	捕获异常 并处理异常，通常异常有不同类型，可分别处理
else	当try语句块正常执行时，无异常产生，执行else语句块
finally	无论是否有异常产生，均执行
raise	自定义异常

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ZeroDivisionError是一个类型，是Exception的子类

def divide(a,b):
    return a/b

while True:
    sFirst = input('First number:')
    sSecond = input('Second number:')
    if sFirst == 'q' or sSecond == 'q':#输入q循环结束
        break
    try:
        iFirst = int(sFirst)
        iSecond = int(sSecond)
        fResult = divide(iFirst,iSecond)
    except (ZeroDivisionError) as e:
        print('you can not divide by 0:',e)
    except (ValueError,TypeError) as e:
        print('illegal value been inputted:',e)
        print(type(e))
    except (Exception) as e:
        print('an expection found, i dont know how to process it.')
        raise#raise指这个异常自己处理不了，扔给外面处理
    else:
        print(sFirst,'/',sSecond,'=',fResult)
    finally:
        print('finally will be executed what ever happens.')

First number:1
Second number:3
1 / 3 = 0.3333333333333333
finally will be executed what ever happens.
First number:q
Second number:q

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thanks for your attention