Python3 捕捉异常

Posted 2020-07-16 侠之大者

可以通过try/except语句来实现捕获异常，如下:

bpython version 0.15 on top of Python 3.5.1+ /usr/bin/python3
>>> x=3
>>> y=0
>>> x/y
Traceback (most recent call last):
  File "<input>", line 1, in <module>
    x/y
ZeroDivisionError: division by zero

捕获异常：

这里只输出提示信息：

#!/usr/bin/env python
# encoding: utf-8
"""
@author: kamil.liu @file: except.py
@time: 16-5-30 上午11:40
"""
x = 3
y = 0
try:
    print(x/y)
except ZeroDivisionError:
    print(‘The second number can`t be zero‘)

结果：

/usr/bin/python3.5 /home/kamil/PycharmProjects/untitled/test1/try/except.py
The second number can`t be zero

Process finished with exit code 0

不加参数，捕获异常：

如果捕获到异常，不处理，只传递异常，可以调用不带参数的raise，如下事例：

传递异常：

#!/usr/bin/env python
# encoding: utf-8

class MuffledCalculator:
    muffled = False
    def calc(self,expr):
        try:
            return eval(expr)
        except ZeroDivisionError:
            if self.muffled:
                print("Division by zero is illegal")
            else:raise
calculator = MuffledCalculator()
print(calculator.calc(‘9/3‘))
#calculator.muffled = True
print(calculator.calc(‘9/0‘))

"""
/usr/bin/python3.5 /home/kamil/PycharmProjects/untitled/test1/try/except.py
3.0
Traceback (most recent call last):
  File "/home/kamil/PycharmProjects/untitled/test1/try/except.py", line 16, in <module>
    print(calculator.calc(‘9/0‘))
  File "/home/kamil/PycharmProjects/untitled/test1/try/except.py", line 8, in calc
    return eval(expr)
  File "<string>", line 1, in <module>
ZeroDivisionError: division by zero

Process finished with exit code 1
"""

不传递异常

#!/usr/bin/env python
# encoding: utf-8

class MuffledCalculator:
    muffled = False
    def calc(self,expr):
        try:
            return eval(expr)
        except ZeroDivisionError:
            if self.muffled:
                print("Division by zero is illegal")
            else:raise
calculator = MuffledCalculator()
print(calculator.calc(‘9/3‘))
calculator.muffled = True
print(calculator.calc(‘9/0‘))

"""
/usr/bin/python3.5 /home/kamil/PycharmProjects/untitled/test1/try/except.py
3.0
Division by zero is illegal
None

Process finished with exit code 0
"""

除0行为发生，屏蔽被打开，calc会返回None。