从文件中读取数据：json 存储数据-python进阶篇十三

import json

#  使用json.dump()把数据存储到文件
numbers = [2, 3, 5, 7, 11, 13]
filename = ‘numbers.json‘
with open(filename, ‘w‘) as f_obj:
    json.dump(numbers, f_obj)

#  使用json.load() 将这个列表读取到内存中
with open(filename) as f_obj:
    numbers = json.load(f_obj)
print(numbers)

#  [2, 3, 5, 7, 11, 13]

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 = ‘username.json‘
try:
    with open(filename) as f_obj:
        username = json.load(f_obj)
except FileNotFoundError: 
    #  如果文件不存在，那么
    username = input("What is your name? ")
    with open(filename, ‘w‘) as f_obj:
        json.dump(username, f_obj)
    print("We‘ll remember you when you come back, " + username + "!")
else:
    #  如果文件存在，那么
    print("Welcome back, " + username + "!")

import json


def greet_user():
    """问候用户，并指出其名字"""
    filename = ‘username.json‘
    try:
        with open(filename) as f_obj:
            username = json.load(f_obj)
    except FileNotFoundError:
        username = input("What is your name? ")
        with open(filename, ‘w‘) as f_obj:
            json.dump(username, f_obj)
        print("We‘ll remember you when you come back, " + username + "!")
    else:
        print("Welcome back, " + username + "!")


greet_user()

import json


def get_stored_username():
    """如果存储了用户名，就获取它"""
    filename = ‘username.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 = ‘username.json‘
    with open(filename, ‘w‘) as f_obj:
        json.dump(username, f_obj)
        return username


def greet_user():
    """问候用户，并指出其名字"""
    username = get_stored_username()
    if username:
        print("Welcome back, " + username + "!")
    else:
        username = get_new_username()
    print("We‘ll remember you when you come back, " + username + "!")


greet_user()