1. 项目

编写一个程序，提示用户输入他喜欢的数字，并使用json.dump()将这个数字存储到文件中。再编写一个程序，从文件中读取这个值，并打印消息“I know your favorite number! It’s _____.”。

2. 代码

import json

def get_favorite_number():
    """如果存储了喜欢的数字，就获取它"""
    filename = 'favorite_number.json'
    try:
        with open(filename) as f_obj:
            favorite_number = json.load(f_obj)
    except FileNotFoundError:
        return None
    else:
        return favorite_number

def get_new_number():
    """提示用户输入喜欢的数字"""
    favorite_number = input("What's your favorite number? ")
    filename = 'favorite_number.json'
    with open(filename, 'w') as f_obj:
        json.dump(favorite_number, f_obj)
    return favorite_number


def read_number():
    """读取喜欢的数字，并打印一段话"""
    favorite_number = get_favorite_number()
    if favorite_number:
        print("I know your favorite number! It's " + favorite_number + " .")
    else:
        favorite_number = get_new_number()
        print("I know your favorite number! It's " + favorite_number + " .")

read_number()

3. 执行结果

没有favorite_number.json文件就创建一个。如果有就直接打印结果。