Python notes-day12-exception capture (registration, login)

Preface
python Grammar learning , Leave it to those who need it , Understand everything ！！

# coding=utf8
# @time:2022/4/21 15:04
# Author  Haoyu 

#  One 、 Application of data persistence 
# 1. Application of data persistence 
'''''''''
1) The data that needs to be persisted should be saved through a file 
2) When you need this persistent data , Do not give values directly , Instead, read the data from the file 
3) If the persistent data changes , You need to write the latest value to this file again 
'''''''''

'''''''''
#  give an example ： Count code execution times ？
# num = 0 #  The number of times when the last execution 
with  open('resource/count.txt','rt',encoding='utf-8') as f:
    num = int(f.read())
num += 1
with open('resource/count.txt','wt',encoding='utf-8') as f:
    f.write(str(num))
print(num)
'''''''''

#  Two 、 Log in to the registration system 
# 1. Display the option interface 
# 2. Give a choice 
# 3. Realize the corresponding function according to the selection 
'''''''''
 Extra code ：
# resource/page The contents of the document :
==========================

   ** Welcome to XX Management system **

       @ 1. deng      record 
       @ 1. notes      book 
       @ 1. refund      Out 

===========================

# filemanager/filemanager.py Content 
#  Define a file reading function 
def read_file(file_url:str):
    with open(file_url,'rt',encoding='utf-8') as f:
        return f.read()

def write_file(file_url:str,date:str,mode='w'):
    with open(file_url,mode,encoding='utf8') as f:
        f.write(date)
        
# resource/users.py Content 


'''''''''
# _______________________________________


'''''''''
#  Official code ！！！！！！！！！！！！！！！！！！！！！
import filemanager.filemanager  #  Call the read file content package module 
def show_main_page():
    # 1) Call directly page.txt Contents of the document 
    # with open('resource/page.txt','rt',encoding='utf-8') as f:
    # page = f.read()
    # print(page)
    #2） Encapsulate the file reading into a function module （ package ）, Call directly 
    page = filemanager.filemanager.read_file('resource\page.txt')
    while True:
        #  Print page 
        print(page)
        #  Give a choice 
        value=int(input(' Please select 1~3：'))
        #  Choose what you can't do 
        if value == 1:
            print(' Sign in ')
            login()
        elif value == 2:
            print(' register ')
            register()
        elif value == 3:
            print(' sign out ')
            return
        else:
            print(' Other situations ')

#  notes   Volume function module 
def register():
    # 1. Enter account number and password 
    user_name = input(' Please enter your account number ：')
    password = input(' Please input a password ：')
    # 2. Judge whether the account can be registered 
    # 1） First get all accounts that have been registered before 
    all_user = eval(filemanager.filemanager.read_file('resource/users.txt'))
    # 2） Check whether the currently entered account is already in the registered account 
    if user_name in all_user:
        print(' This account has been registered ')
        return
    # 3. register 
    # {} -> {user:pw}
    all_user[user_name] = password
    filemanager.filemanager.write_file('resource/users.txt',str(all_user))
    print(' congratulations ！！！！ Registered successfully ！')


#  Login function module 
def login():
    # 1. Enter account number and password 
    user_name = input(' Please enter your account number ：')
    password = input(' Please input a password ：')
    # 2. Judge whether the login is successful 

    # 0) Get the previously registered account and the corresponding password 
    users = eval(filemanager.filemanager.read_file('resource/users.txt'))
    # 1） Judge whether the entered account is a registered account 
    if user_name not in users:
        print(' The account is not registered , Please register your account first ')
        return
    # 2） Judge whether the entered password is the same as the password at the time of registration 
    if users[user_name] != password:
        print(' Wrong password ')
        return
    print(' Login successful ')


if __name__=='__main__':

    show_main_page()
'''''''''


#  3、 ... and 、 Exception trapping 
# 1. abnormal 
#  Program error is also called program exception ; If an exception occurs during the execution of the program , Then the program will end where there is an exception .
'''''''''
print('123')
list1 = [1,2,3]
print(list1[4])    #  Report errors 
print('321')
'''''''''

# 2. Exception trapping 
#  Exception capture is to prevent the program from crashing when there is another exception , Don't complain , Can continue to execute ;
#  When to catch exceptions ： Clearly know that some code may have errors , But there is no way or need to modify this code to avoid exceptions , You can use exception capture .
'''''''''
1) Grammar 1 ：( Catch all types of exceptions )
try:
     Code segment 1（ Code snippets that need to catch exceptions ）
except:
     Code segment 2（ A code segment that executes only when an exception occurs ）
 Other statements ......

 Execution process ： Execute the code segment first 1, If there is no exception, do not execute the code segment 2, Directly execute the following (try) The sentence of ;
         If there is an anomaly , The program doesn't crash , Execute the code snippet now 2, Execute other statements after execution 
#  give an example 
try:
    age = int(input(' Please enter age ：'))
except:
    print(' Incorrect age entered ')

print(' Continue to open the game ')

2) Grammar II ：()
try:
     Code segment 1（ Code snippets that need to catch exceptions ）
except  Exception types :
     Code segment 2（ Only when the specified exception type occurs will ）

#  give an example 
try:
    print(int('abc'))
except ValueError:
    print(' Something unusual happened ')

print(' Continue to open the game ')

3) Grammar 3 ：()
try:
     Code segment 1（ Code snippets that need to catch exceptions ）
except ( Exception types 1, Exception types 2,.....):
     Code segment 2（ Only when the specified exception type occurs will ）

'''''''''


try:
    print(int('abc'))
except ValueError:
    print(' Something unusual happened ')

print(' Continue to open the game ')

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