Python Day-例外处理
例外处理
- >例外是一个异常事件,发生在程序执行过程中,并突然停止程序(立即)
>->异常处理允许响应错误,而不是崩溃运行程序。
语法:>
try: # code that might raise an exception except someexception: # code to handle the exception else: # code to run if no exception occurs finally: # code to run regardless of whether an exception occurs
尝试,除了,否则,最后阻止
>
1。尝试块try块包含可能引起异常的代码。
4。最后阻止(可选)
>通常用于清理操作,例如关闭文件或释放资源。>>示例:
enter no.10enter no. 0no2 should not be zero. check no2 value 10
try: no1 = int(input("enter no.")) no2 = int(input("enter no. ")) print(no1//no2) print(no1+no2)except zerodivisionerror: print("no2 should not be zero. check no2 value ")except valueerror: print("inputs should be numbers ")
>输出:
enter no.10enter no. teninputs should be numbers
3)
try: no1 = int(input("enter no.")) no2 = int(input("enter no. ")) print(no1//no2) print(no1+no2) f = open("pqrs.txt")except zerodivisionerror: print("no2 should not be zero. check no2 value ")except valueerror: print("inputs should be numbers ")except: print("something went wrong")
>输出:
#if all inputs are correctenter no.10enter no. 5215#if any error not specified particularlyenter no.10enter no. 5215something went wrong#if zerodivisionerrorenter no.10enter no. 0no2 should not be zero. check no2 value#if valueerrorenter no.10enter no. teninputs should be numbers
:
**注意:**
- 处理不可预测的错误时,请使用try-exce->处理预期条件时使用if-else
追溯模块:
python中的追溯模块用于提取,格式和打印错误跟踪信息,有助于调试和日志记录异常。
>示例:1
import tracebacktry: no1 = int(input("enter no.")) no2 = int(input("enter no. ")) print(no1//no2) print(no1+no2) f = open("pqrs.txt") print(f.read())except (valueerror, zerodivisionerror) as msg: print("check ",msg)except: print("something went wrong") traceback.print_exc()
>输出:
enter no.10enter no. 0check integer division or modulo by zero
import tracebacktry: no1 = int(input("enter no.")) no2 = int(input("enter no. ")) print(no1//no2) print(no1+no2) f = open("pqrs.txt") print(f.read())except (valueerror, zerodivisionerror) as msg: print("check ",msg)except: print("something went wrong") traceback.print_exc()finally: print("check finally message")
>输出:
enter no.10enter no. 10120something went wrongtraceback (most recent call last): file "/home/guru/desktop/guru/python/user.py", line 7, in <module> f = open("pqrs.txt") ^^^^^^^^^^^^^^^^filenotfounderror: [errno 2] no such file or directory: 'pqrs.txt'check finally message
捕获多个特定异常:
>->我们可以在单个单个中处理多个异常,除了使用元组。
->使用,因为我们也可以为异常提供一个可变名称。
trackback.print_exc():它提供详细的错误信息(行号,错误类型,消息)。
class employee: passemp1 = employee()emp2 = employee()print(emp1)print(emp2)
>输出:
<__main__.employee object at 0x730a36434110><__main__.employee object at 0x730a36434080>
pass关键字的意思是“无所事事”(占位符),因此该类目前为空(它没有属性或方法)。
__ doc __(docstring属性)
> __doc__属性用于访问类,功能,模块或方法的docstring。 docstring是一个多行字符串,提供有关对象的文档,该对象在triple引号('''''')中声明。>示例:
class employee: '''this class is for creating employees'''print(employee.__doc__)
4
this class is for creating employees
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->“ self”用于访问和操纵类中的实例变量和方法。-> self代表类的实例。>
>特定对象的
- 使用self.variable_name定义的>。->对于每个对象唯一。
>示例:1
class employee: def work(self): print(self.empname, self.job_nature)emp1 = employee()emp1.empname = 'guru'emp1.job_nature = "designing"emp2 = employee()emp2.empname = "pritha"emp2.job_nature = "development"emp1.work()emp2.work()
>输出:
guru designingpritha development
>示例:2类,带3种方法:
class employee: organization = "infosys" def work(self): print(self.empname, self.job_nature, self.organization) def take_leave(self): pass def promote(self): passemp1 = employee()emp1.empname = 'guru'emp1.job_nature = "designing"emp2 = employee()emp2.empname = "pritha"emp2.job_nature = "development"emp1.work()emp2.work()
>输出:
guru designing infosyspritha development infosys
类特定信息:
类别的信息是指在类的所有实例(对象)之间共享的数据。
>示例:
class employee: def work(self): print(self.empname, self.job_nature, self.organization) def take_leave(self): pass def promote(self): passemp1 = employee()emp1.empname = 'guru'emp1.job_nature = "designing"emp2 = employee()emp2.empname = "pritha"emp2.job_nature = "development"employee.organization = "infosys"emp1.work()emp2.work()
>输出:
guru designing infosyspritha development infosys