[Network Security Learning Article 35]: Python modules and functions and exception capture

table of Contents

 

Modules and functions and exception catching

Modules and functions

The formal and actual parameters of the function

Exception catch

Exception 1: ZeroDivisionError

Exception 2: ValueError

Exception 3: KeyboardInterrupt and EOFError

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Modules and functions and exception catching

 

Modules and functions

1. Define the module name can not be Kaito with numbers

2. Cannot duplicate the name of the default module

The module file must be executed in the same directory or the module file is valid in the lib file

Examples:

print("*"*20)

     hello

print("*"*20)

Create a functional module that can be called import

Contains a function function in the module, the function returns 20 *

Create Module

"""
介绍模块的作用
里面包含的功能
作者的联系方式
"""

star = "**********"
"star变量的作用是赋了10个星号"


def p_star():
    "我的作用返回20个星号"
    return "*"*20

 Call module

import printstar

#print(help(printstar))
#print(dir(printstar))
#print(help(printstar.p_star))

star20 = printstar.p_star()
print(printstar.star)
print("        hello")
print(star20)

Here we can also use the help () and dir () functions to view the module functions

 

The formal and actual parameters of the function

 

The function realizes the division calculation of two values

def division(a,b):
    num = a / b
    return num

numa = int(input("请输入被除数："))
numb = int(input("请输入除数："))
endnum = division(numa,numb) 
print(endnum)

Actual parameters: numa, numb 

Formal parameters: a, b

 

Exception catch

benefit:

When our program is running, some exceptions will inevitably occur, such as the user's intentional input error, which causes a function of the program to crash. We capture the exception of the program to correct or warn the user's input.

structure:

try:

    Captured substatement

except (exception type 1, type 2, ...):

    pass/print

 

Exception 1: ZeroDivisionError

In the above division program, when we output a divisor of 0, the program reports an error

How can we control it so that he does n’t report an error?

def division(a,b):
    num = a / b
    return num

numa = int(input("请输入被除数："))
numb = int(input("请输入除数："))
try:
    endnum = division(numa,numb)
    print(endnum)
except ZeroDivisionError:
    print("除数不能为0")

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Exception 2: ValueError

Also when we enter letters, the program will also report an error

def division(a,b):
    num = a / b
    return num
try:
    numa = int(input("请输入被除数："))
    numb = int(input("请输入除数："))

    endnum = division(numa,numb)
    print(endnum)
except ZeroDivisionError:
    print("除数不能为0")

except ValueError:
    print("请输入正常的整数")

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Exception 3: KeyboardInterrupt and EOFError

We directly press CTRL + D, the program will report the following error

We directly press CTRL + C, the program will report the following error

def division(a,b):
    num = a / b
    return num
try:
    numa = int(input("请输入被除数："))
    numb = int(input("请输入除数："))

    endnum = division(numa,numb)
    print(endnum)
except ZeroDivisionError:
    print("除数不能为0")

except ValueError:
    print("请输入正常的整数")
except (KeyboardInterrupt,EOFError):
    pass

pass directly ends