python 错误处理：try..exc
- 2020 年 1 月 10 日
- 筆記
python错误继承表：
https://docs.python.org/3/library/exceptions.html#exception-hierarchy
格式：
def 函数()：
try:
内容 ###正确输出
except 错误表 in e:
输出内容 ###错误输出
finally:
输出内容 ##必定输出
print('END') ##必定输出
#!/usr/bin/python # -*- coding: utf-8 -*- 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()
运行结果：
('Error:', ZeroDivisionError('integer division or modulo by zero',)) finally...
a.面对函数层层调用，try…except能捕捉得到。
b.类的子类错误也能捕捉得到，如捕捉ValueError错误，顺便也会把UnicodeError也捕捉了
+-- ValueError | +-- UnicodeError | +-- UnicodeDecodeError | +-- UnicodeEncodeError | +-- UnicodeTranslateError
记录错误到日志文件：
#!/usr/bin/python # -*- coding: utf-8 -*- import logging ###########记得导入模块 def foo(s): return 10 / int(s) def bar(s): return foo(s) * 2 def main(): try: bar('0') except Exception as e: logging.exception(e) #########模块函数使用 print ('haha') main() print ('END')
运行结果：
haha END ERROR:root:division by zero Traceback (most recent call last): File "/usercode/file.py", line 14, in main bar('0') File "/usercode/file.py", line 10, in bar return foo(s) * 2 File "/usercode/file.py", line 7, in foo return 10 / int(s) ZeroDivisionError: division by zero
当不用错误调试时，普通的程序出错会调用栈Traceback提示错误
def foo(s): return 10 / int(s) def bar(s): return foo(s) * 2 def main(): bar('0') main()
运行结果：
Traceback (most recent call last): File "/usercode/file.py", line 13, in <module> main() File "/usercode/file.py", line 11, in main bar('0') File "/usercode/file.py", line 8, in bar return foo(s) * 2 File "/usercode/file.py", line 5, in foo return 10 / int(s) ZeroDivisionError: integer division or modulo by zero
抛出错误：raise
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!', e) raise bar()
运行结果：
('ValueError!', ValueError('invalid value: 0',)) Traceback (most recent call last): File "/usercode/file.py", line 17, in <module> bar() File "/usercode/file.py", line 12, in bar foo('0') File "/usercode/file.py", line 7, in foo raise ValueError('invalid value: %s' % s) ValueError: invalid value: 0
