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。
- >
- 如果发生异常,则将其传递给块。
-
block处理在try块中发生的异常。
- >您可以指定不同类型的异常,也可以使用一般条款以捕获所有异常。
2。除了block
3。 else block(可选)
仅在try块中出现无例外的情况。
4。最后阻止(可选)
- 最终块执行,无论是否出现异常。
>
>通常用于清理操作,例如关闭文件或释放资源。
>示例:
- >
- 1)
-
try: no1 = int(input("enter no.")) no2 = int(input("enter no. ")) print(no1//no2) except zerodivisionerror: print("no2 should not be zero. check no2 value ") print(no1+no2)
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>输出:
enter no.10 enter no. 0 no2 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.10 enter no. ten inputs 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 correct enter no.10 enter no. 5 2 15 #if any error not specified particularly enter no.10 enter no. 5 2 15 something went wrong #if zerodivisionerror enter no.10 enter no. 0 no2 should not be zero. check no2 value #if valueerror enter no.10 enter no. ten inputs should be numbers
异常处理和条件语句之间的
:
>
**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:
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 traceback try: 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.10 enter no. 0 check integer division or modulo by zero
>示例:2
import traceback try: 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.10 enter no. 10 1 20 something went wrong traceback (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: pass emp1 = 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“”;
->“ 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 designing pritha 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): pass 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 designing infosys pritha 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): pass emp1 = 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 infosys pritha development infosys
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