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Learn this trick and never be afraid to let the code collapse by mistake

2022-07-28 02:26:00 【51CTO】

Reading guide

I learned a very interesting move today , Ride the hot iron to share a wave ！

More specifically, it is about python Application of exception handling , Realize a function that you can be forgiven for wrong hand input , It's very easy to use and interesting >_<

If you learn this trick, you will no longer be afraid to let the code collapse by mistake _ exception handling

One 、 Exception and exception handling

In order to have a clearer understanding of what needs to be done next , We need to understand a few concepts first .

First of all , What is an anomaly . An exception is an event , This event occurs during program execution , It affects the normal execution of the program .

An inappropriate metaphor is , When you are picking up girls , Suddenly a silly Eagle came and said you had bad breath , Always fart , It directly makes you unable to pick up girls normally .

second , What exception handling , In order to solve when an exception occurs , We don't want our program to hang up , And some operations .

And exception handling is similar to when you know this unlucky guy is coming , There must be no good words , You predicted in advance that it would happen , Backhand is to slap him , Then let him talk well , In the end, things are going in a good direction .

Two 、 Small application of exception handling

We often encounter, for example, the need to enter a password , When you enter the wrong password , You don't want to quit the system , Instead, re-enter the password ; Or to read a picture , But sometimes the hand hits the wrong path by mistake , You don't want the whole code to run again , In order for the code to recognize your mistakes and allow you to re-enter , Until you finally enter the path correctly .

       
       ''
       
       ' Realize manual input of address , And read the picture '
       
       ''  
       
       import 
       
       matplotlib.
       
       image 
       
       as 
       
       mpimg 
       
       # For reading pictures   
       
       path 
       
       = 
       
       imput(
       
       ' Please enter the path ：')  
       
       src 
       
       = 
       
       mpimg.
       
       imread(
       
       path)
      
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2.
3.
4.

       
       ##
       
       # Results output ：  
       
        Please enter the path ：xxx(
       
        Lose in disorder )  
       
       FileNotFoundError: [
       
       Errno 
       
       2] 
       
       No 
       
       such 
       
       file 
       
       or 
       
       directory: 
       
       'xxx'
      
1.
2.
3.

In this case , Wrong address , The code stops directly , It's not what we want

How can we solve it ？

Ideas ：

（1） Find out what may go wrong , Make detection and judgment ;

（2） When the input is correct , Go directly to the next step ;

（3） When the input is wrong , Re execution , Until it's right .

       
       # 
       
        Import the necessary libraries , One is to read pictures, the other is to display pictures     
       
       import 
       
       matplotlib.
       
       image 
       
       as 
       
       mpimg    
       
       import 
       
       matplotlib.
       
       pyplot 
       
       as 
       
       plt    
       
# 
       
       （1） For possible mistakes , Set exception handling     
       
       def 
       
       url_is_correct():    
       
       try:  
       
       #（2） When the input is correct , Go directly to the next step ;    
       
       url 
       
       = 
       
       input(
       
       ' Please enter the correct picture path ：')    
       
       queryDir 
       
       = 
       
       url    
       
       src 
       
       = 
       
       mpimg.
       
       imread(
       
       queryDir)    
       
       return 
       
       queryDir    
       
       except:    
       
       print(
       
       ' Wrong picture path , Please re-enter ：')    
       
       return 
       
       url_is_correct() # 
       
       （3） When the input is wrong , Re execution , Until it's right .    
       
       queryDir 
       
       = 
       
       url_is_correct()    
       
       queryImg 
       
       = 
       
       mpimg.
       
       imread(
       
       queryDir)    
       
       plt.
       
       imshow(
       
       queryImg,
       
       cmap
       
       =
       
       plt.
       
       cm.
       
       gray)    
       
       plt.
       
       show()
      
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Complete code ： https://github.com/DWCTOD/AI_study/blob/master/06-yichangchuli

3、 ... and 、 Effect display

Use the screen recording software provided by the system to operate it again , Let everyone see more clearly ：

If you learn this trick, you will no longer be afraid to let the code collapse by mistake _github_02

It's hard , I don't know why there is a problem with the displayed picture , This screen recording software is poisonous , It's OK to see it on your computer ！！！ Study it later .

Here is just a simple demonstration of an interesting function , For exception handling , I didn't learn deeply enough , If you get a chance later , Continue to study ！

If you learn this trick, you will no longer be afraid to let the code collapse by mistake _ exception handling _03

If you learn this trick, you will no longer be afraid to let the code collapse by mistake _ exception handling _04

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本文为[51CTO]所创，转载请带上原文链接，感谢
https://yzsam.com/2022/209/202207280048443733.html

当前位置：网站首页>Learn this trick and never be afraid to let the code collapse by mistake

Learn this trick and never be afraid to let the code collapse by mistake

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