python异常处理

>>> print(a)
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    print(a)
NameError: name 'a' is not defined

try:
    语句块
except:
    异常处理的语句

def calcu():
    a,b=eval(input())
    try:
        end=a/b
        print('end=',end)
    except:
        print('error')

>>> calcu()
1,2
end= 0.5
>>> calcu()
1,0
error

def main():
    a,b=eval(input())
    try:
        s=a/b
        print('s=',s)
    except TypeError :
        print('数据类型异常,')
    except ZeroDivisionError as e:
        print('除数为0，',e)
    except:
        print(' 发生exception')
    else:
        print('正常结束')

>>> main()
1,'1'
数据类型异常,
>>> main()
1,0
除数为0， division by zero
>>> main()
2,3
s= 0.6666666666666666
正常结束

import os
def main():
    try:
        f1=open('C:\\HelloWorld.txt','r+')
        f2=open('c:\\test.txt','w+')
        f3=f1.read()
        f1.seek(0)
        print(f3)
        print('----------')
        for c in f1:
            f2.write(c)
    except:
        print(' has except')
    finally:
        print('close file')
        f2.flush()
        #f2.seek(0)
        f6=f2.read()
        print(f6)
        f1.close()
        f2.close()

public class HelloWorld{
 
public  static void main(String []args)
{
  System.out.println("helllo world");
}


}
----------
close file

import math
def getException(lev):
    if lev<0:
        raise Exception('invalid lev')
    

def getSqrt(num):
    try:
        getException(num)
        i=0
        y=math.sqrt(num)
        print('{0}*{1}={2}'.format(y,y,num))
    except Exception as e:
        print('error',e)

class  FileException(Exception):
    def __init__(self,arg):
        self.arg=arg
    def __str__(self):
        return repr(self.arg)
    
try:
    raise FileException('\home')
except FileException  as e:
    print('error ',e.arg)

IPython 6.2.1 -- An enhanced Interactive Python.
error  \home