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Python Day-例外处理

百变鹏仔 2小时前 #Python
文章标签 Python

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
2)
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 
异常处理和条件语句之间的区别


>


**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
>示例:2

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)。

糟糕:


>显示对象的存储器位置:

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__)
>输出:


4

this class is for creating employees

自我关键字:

立即学习“Python免费学习笔记(深入)”;

->“ 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