《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

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

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

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1. >>> my_list = [1,2,3]
   
2. >>> my_list[3]   # 此例索引没有3
   
3. Traceback (most recent call last):
   
4.   File "<pyshell#24>", line 1, in <module>
   
5.     my_list[3]
   
6. IndexError: list index out of range
   
7. >>> my_list[2]
   
8. 3

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

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

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

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1. >>> 1 + '1'  # 类型错误
   
2. Traceback (most recent call last):
   
3.   File "<pyshell#32>", line 1, in <module>
   
4.     1 + '1'
   
5. TypeError: unsupported operand type(s) for +: 'int' and 'str'

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1. >>> 5 / 0  # 除数为0错误
   
2. Traceback (most recent call last):
   
3.   File "<pyshell#33>", line 1, in <module>
   
4.     5 / 0
   
5. ZeroDivisionError: int division or modulo by zero

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