1.基础模块-异常类

raise 语句格式为：

raise [exceptionName [(reason)]]

异常情况

常见的几种异常情况类别：

• AssertionError
  - 当 assert 断言条件结果为假时（False），程序运行会停止并抛出 AssertionError 异常

>>> demo_list = ['C语言中文网']
>>> assert len(demo_list) > 0
>>> demo_list.pop()
'C语言中文网'
>>> assert len(demo_list) > 0
Traceback (most recent call last):
  File "<pyshell#6>", line 1, in <module>
    assert len(demo_list) > 0
AssertionError

• AttributeError
  - 当访问的对象属性不存在时抛出异常

	>>> demo_list = ['C语言中文网']
>>> demo_list.len
Traceback (most recent call last):
  File "<pyshell#10>", line 1, in <module>
    demo_list.len
AttributeError: 'list' object has no attribute 'len'

• IndexError
  - 索引超出序列范围会引发异常

>>> demo_list = ['C语言中文网']
>>> demo_list[3]
Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    demo_list[3]
IndexError: list index out of range

• KeyError
  - 字典中缺失key值

>>> demo_dict={'C语言中文网':"c.biancheng.net"}
>>> demo_dict["C语言"]
Traceback (most recent call last):
  File "<pyshell#12>", line 1, in <module>
    demo_dict["C语言"]
KeyError: 'C语言'

• NameError
  - 访问一个未声明的变量，引发异常

>>> C语言中文网
Traceback (most recent call last):
  File "<pyshell#15>", line 1, in <module>
    C语言中文网
NameError: name 'C语言中文网' is not defined

• TypeError
  - 不同类型数据之间的错误操作

>>> 1+'C语言中文网'
Traceback (most recent call last):
  File "<pyshell#17>", line 1, in <module>
    1+'C语言中文网'
TypeError: unsupported operand type(s) for +: 'int' and 'str'