python14异常处理

def test_div(num1,num2):
    return num1 / num2

if __name__ == "__main__":
    try:
        print(test_div(5,"a"))
    except ZeroDivisionError:
        print("除数不能为零")
    except TypeError as err:
        print("输入数字")
        print(err)

结果：
输入数字
unsupported operand type(s) for /: 'int' and 'str'

def test_file():
    try:
        f = open("test.txt","r")
        rest = f.read()
        print(rest)
    except:
        print("eror")
    finally:
        try:#加入新得try，防止文件没有被打开而需要关闭所产生的异常
            f.close()
            print("quan")
        except:
            pass
    #try:

if __name__ == "__main__":
    test_file()

class ApiException(Exception):
    """我的自定义异常"""
    err_code = ""
    err_msg = ""
    def __init__(self, err_code=None, err_msg=None):
        #111111如果存在则使用自己，要不就使用传进来的参数
        self.err_code = self.err_code if self.err_code else err_code
        self.err_msg = self.err_msg if self.err_msg else err_msg

    def __str__(self):
        return  "Error:{0} - {1}".format(self.err_code,self.err_msg)

class InvalidCtrlexec( ApiException):
    err_code = "4001"
    err_msg = "bbbbb"

class BagException(ApiException):
    err_code = "4002"
    err_msg = "quanzhiqiang"

def test_exec(num1,num2):
    """除法的实习"""
    #两个数必须为整数
    if not isinstance(num1,int) or not isinstance(num2,int):
        raise BagException()#BagException("88","9999")也是一样的输出，因为11111
    if num2 == 0:
        raise ApiException("40002","ccccc")
    return num1 / num2

if __name__ == "__main__":
    try:
        rest = test_exec(5,"2")
        """
        当为（5，0）结果：处处哦
        Error:40002 - ccccc
        当为（5，”quan”）结果为：
        quanqqqq
        Error:4002 - quanzhiqiang
        """
        print(rest)
    except BagException as B_err: #因为这个BagException是ApiException的子类，捕获小的再捕获大范围的
        print("quanqqqq")
        print(B_err)
    except ApiException as err:
        print("处处哦")
        print(err)

class MyException(Exception):
    pass

def v_for():
    for i in range(1,100):
        if i == 20:
            raise MyException
        print(i)

def call_v_for():
    print("aaaaaaaaaaaaaaaa")
    v_for()
    print("bbbbbbbbbbbbbbb")

def test_raise():
    print("ceshi")
    try:
        call_v_for()
    except MyException:
        print("88888888888888888")
    print("endend")

if __name__ == "__main__":
    test_raise()

结果：
ceshi
aaaaaaaaaaaaaaaa
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
88888888888888888
endend

因为异常是由原函数触发，如果没有捕获，就会一层一层往调用函数传递
这里在最外层捕获，所以call_v_for里面没有 print("bbbbbbbbbbbbbbb")