Python3读取文件和异常处理demo案例

左手的ㄟ右手 2022-12-06 01:15 178阅读 0赞

## 该案例学习了一下内容： ##

1.  如何使用文件；
2.  如何一次性读取整个文件；
3.  如何写入文件，以及将文本附加到文件尾部；
4.  异常捕获处理
5.  存储Python数据结构

remeaber\_name.py

import json
    
    def get_stored_name():
         """如果用户名存在就获取"""
         filename = 'names.json'
         try:
            with open(filename) as f_obj:
                username = json.load(f_obj)
         except FileNotFoundError:
            return None
         else:
            return username
    
    def get_new_name(new_name,is_exist=True):
        """提示用户输入用户名"""
        #new_name  = input("Enter your name:")
        is_exist = is_exist_name(new_name)
        if is_exist:
            return new_name,is_exist
        else:
            #存储用户名
            return do_store_name(new_name),is_exist
    
    
    def is_exist_name(name):
        """验证用户名是否已存在"""
        filename = 'names.json'
        try:
            with open(filename) as f_obj:
                names = json.load(f_obj)
        except FileNotFoundError:
            names = []
            json.dump(names, open(filename, 'w'))
            return False
        else:
            if name in names:
                return True
            else:
                return False
    
    
    def do_store_name(new_name):
        filename = "names.json"
        readed = json.load(open(filename, 'r'))
        readed.append(new_name)
        with open(filename,'w') as f_obj:
             json.dump(readed,f_obj)
        return new_name
    
    def greet_user(username):
        username,is_exist = get_new_name(username)
        #username = get_stored_name()
        if is_exist:
            print("Welcome back,"+ username +"!")
        else:
          # username = get_new_name()
            print("We'll remeber you when you com back," + username +"!")
    
    if __name__ == "__main__":
        while True:
            input_str = input("请输入登录名(输入'Q'录入结束):")
            if input_str == 'Q':
                break
            greet_user(input_str)

names.json

["KEKE", "LELE", "JIZHUANG.WANG", "XIAYU", "XIA"]

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