《零基础入门学习python》第三十二讲笔记：异常处理：你不可能总是对的

bozhen

Exception :异常

Assert:  断言：当Assert 后面条件为假时，自动抛出一个异常，为真则继续代码

>>> my_list = ['小甲鱼是帅哥']
>>> assert len(my_list) > 0
>>> my_list.pop()
'小甲鱼是帅哥'
>>> assert len(my_list) > 0   # assert 后面条件为假，抛出AssertionError
Traceback (most recent call last):
  File "<pyshell#21>", line 1, in <module>
    assert len(my_list) > 0
AssertionError

>>> my_list.fishc   # 列表没有fishc方法
Traceback (most recent call last):
  File "<pyshell#22>", line 1, in <module>
    my_list.fishc
AttributeError: 'list' object has no attribute 'fishc'

>>> my_list = [1,2,3]
>>> my_list[3]   # 此例索引没有3
Traceback (most recent call last):
  File "<pyshell#24>", line 1, in <module>
    my_list[3]
IndexError: list index out of range
>>> my_list[2]
3

>>> my_dict = {'one':1,'two':2,'three':3}
>>> my_dict['one']
1
>>> my_dict['four']  # 此例，关键字没有four
Traceback (most recent call last):
  File "<pyshell#28>", line 1, in <module>
    my_dict['four']
KeyError: 'four'
>>> my_dict.get('four')   # 用get方法取没有的键不会报错

>>> fishc  # 没有fishc这个变量
Traceback (most recent call last):
  File "<pyshell#30>", line 1, in <module>
    fishc
NameError: name 'fishc' is not defined

>>> print 'I love FishC.com'   # 语法错误
SyntaxError: invalid syntax (<pyshell#31>, line 1)

>>> 1 + '1'  # 类型错误
Traceback (most recent call last):
  File "<pyshell#32>", line 1, in <module>
    1 + '1'
TypeError: unsupported operand type(s) for +: 'int' and 'str'

>>> 5 / 0  # 除数为0错误
Traceback (most recent call last):
  File "<pyshell#33>", line 1, in <module>
    5 / 0
ZeroDivisionError: int division or modulo by zero

>>>