20190601 Python练习记录

>>> def foo():
    r=some_function()
    if r==(-1):
        return (-1)
    return r
def bar():
    r=foo()
    if  r==(-1):
        print('Error')
    else:
        pass

>>> try:
    print('try..')
    r=10/0
    print('resultL',r)
except ZeroDivisionError as e:
    print('except:',e)
finally:
    print('finally...')
print('end')
try..
except: division by zero
finally...
end
>>> 

try:
    print('try..')
    r=10/int('a')
    print('resultL',r)
except ValueError as e:
    print('ValueError:',e)
except ZeroDivisionError as e:
    print('except:',e)
finally:
    print('finally...')
print('end')

try:
    print('try..')
    r=10/int('2')
    print('resultL',r)
except ValueError as e:
    print('ValueError:',e)
except ZeroDivisionError as e:
    print('except:',e)
else:
    print('no error!')
finally:
    print('finally...')
print('end')

>>> def foo(s):
    return 10/int(s)
def bar(s):
    return foo(s)*2
def main():
    try:
        bar('0')
    except Exception as e:
        print('Error:',e)
    finally:
        print('finally...')
        
>>> main()
Error: division by zero
finally...
>>> 

class FooError(ValueError):
    pass
def foo(s):
    n=int(s)
    if n==0:
        raise FooError('invalid value:%s'%s)
    return 10/n
foo('0')

def foo(s):
    n=int(s)
    if n==0:
        raise ValueError('invalid value:%s'%s)
    return 10/n
def bar():
    try:
        foo('0')
    except ValueError as e:
        print('ValueError')
        raise
bar()