Python数据的存储和读取 学习笔记

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"""存储数据"""
# 使用模块json存储数据
# 防止程序停止运行时用户数据丢失
import json
numbers = [2, 3, 4, 5]
filename = 'numbers.json'
with open(filename, 'w') as f_obj:
# 写入模式
json.dump(numbers, f_obj)
import json
filename = 'numbers.json'
with open(filename) as f_obj:
# 读取模式
numbers = json.load(f_obj)
print(numbers)
"""结合数据存储和异常处理"""
import json
# 如果以前存储了用户名，就加载它
# 否则，就提示用户输入用户名并存储它
filename = 'numbers.json'
try:
with open(filename) as f_obj:
user = json.load(f_obj)
except FileNotFoundError:
# 提示输入
user = input('Please enter your name:')
with open(filename, 'w') as f_obj:
json.dump(user, f_obj)
print('We will remember you when you come back ' + user + '.')
else:
print('Welcome back ' + user + '!')
# 对存储、加载用户名代码进行重构
import json
def get_stored_username():
"""如果存储了用户名，就获取它"""
filename = 'numbers.json'
try:
with open(filename) as f_obj:
username = json.load(f_obj)
except FileNotFoundError:
return None
else:
return username
def get_new_username():
"""提示用户输入用户名"""
username = input('What is your name?')
filename = 'numbers.json'
with open(filename) as f_obj:
json.dump(username, f_obj)
return username
def greet_user():
"""问候用户，并指出它名字"""
username = get_stored_username()
if username:
print('Welcome back ' + username + '.')
else:
get_new_username()
print('We will remember you when you come back' + username)
greet_user()