异常处理
# Author:Li Dongfei
data = {'name':'dongfei'}
l = []
try:
data['name']
l[1]
except KeyError as e:
print("没有这个Key", e)
except IndexError as e:
print("列表操作错误", e)
异常处理2(不建议这样写,特殊情况除外)
# Author:Li Dongfei
data = {'name':'dongfei'}
l = []
try:
data['name']
l[1]
except (KeyError,IndexError) as e:
print("没有这个Key", e)
异常处理(抓住所有的错误,一般不用)
# Author:Li Dongfei
data = {'name':'dongfei'}
l = []
try:
data['name']
l[1]
except Exception as e:
print("出错了", e)
未知错误
# Author:Li Dongfei
data = {'name':'dongfei'}
l = [2,3]
try:
data['name']
l[1]
except KeyError as e:
print("没有这个Key", e)
except IndexError as e:
print("列表操作错误", e)
except Exception:
print("未知错误")
无异常
# Author:Li Dongfei
data = {'name':'dongfei'}
l = [2,3]
try:
data['name']
l[1]
except KeyError as e:
print("没有这个Key", e)
except IndexError as e:
print("列表操作错误", e)
except Exception:
print("未知错误")
else:
print("一切正常")
最后的处理(不管有错无错都执行)
# Author:Li Dongfei
data = {'name':'dongfei'}
l = [2,3]
try:
data['name']
l[1]
except KeyError as e:
print("没有这个Key", e)
except IndexError as e:
print("列表操作错误", e)
except Exception:
print("未知错误")
else:
print("一切正常")
finally:
print("不管有错无错都执行")
常见异常种类
AttributeError 试图访问一个对象没有的树形,比如foo.x,但是foo没有属性x
IOError 输入/输出异常;基本上是无法打开文件
ImportError 无法引入模块或包;基本上是路径问题或名称错误
IndentationError 语法错误(的子类) ;代码没有正确对齐
IndexError 下标索引超出序列边界,比如当x只有三个元素,却试图访问x[5]
KeyError 试图访问字典里不存在的键
KeyboardInterrupt Ctrl+C被按下
NameError 使用一个还未被赋予对象的变量
SyntaxError Python代码非法,代码不能编译(个人认为这是语法错误,写错了)
TypeError 传入对象类型与要求的不符合
UnboundLocalError 试图访问一个还未被设置的局部变量,基本上是由于另有一个同名的全局变量,
导致你以为正在访问它
ValueError 传入一个调用者不期望的值,即使值的类型是正确的
自定义异常
# Author:Li Dongfei
class MyException(Exception):
def __init__(self,msg):
self.msg = msg
def __str__(self):
return self.msg
try:
raise MyException('我的异常')
except MyException as e:
print(e)