4.4python作业

# 10-4
file_name = 'guest_book.txt'

with open(file_name, 'a') as file:
    while(True):
        name = input("Please enter your name:")
        if(name == 'quit'):
            break
        file.write(name+ '\n')


# 10-5

file_name = 'reasons.txt'

with open(file_name, 'a') as file:
    while True:
        reason = input("Why do you like programming?")
        if(reason =='quit'):break

        file.write(reason+ '\n')

# 10-7

while True:
    try:
        num_a = int(input("Please enter the first number:"))
        num_b = int(input("Please enter the second number:"))
    except ValueError:
        print("Sorry, please enter a number!")
    else:
        print(num_a + num_b)

# 10-11

import json

file_name = 'test.txt'

with open(file_name,'w') as file:
    num = input("Please enter your favorite number:")
    str = "I know your favorite number! It's "+ num + '.'
    json.dump(str, file)

with open(file_name) as file:
    str_in_json = json.load(file)
    print(str_in_json)

# 10-13

import json

def get_stored_username():
    try:
        file_name = 'username.json'
        with open(file_name) as file:
            name = json.load(file)
    except FileNotFoundError:
        return None
    else:
        return name


def get_new_username():
    username = input("What is your name?")
    filename = 'username.json'
    with open(filename, 'w') as file:
        json.dump(username, file)

    return username

def greet_user():

    username = get_stored_username()

    if username:
        ans = input("Is " + username + " your name? Y/N")
        if ans == 'Y' or ans == 'y':
            print("Welcome back, " + username + '!')
        else:
            username = get_new_username()
            print("We'll remember you when you come back, " + username + '!')
    else:
        username = get_new_username()
        print("We'll remember you when you come back, " + username + '!')

greet_user()