[python]文件和异常

import json
#处理ZeroDivisionError异常
try:
    print(5/0)
except ZeroDivisionError:
    print("You can't divide by zero!")

#Example 1
print("Give me two numbers, and I'll divide them.")
print("Enter 'q' to quit.")

while True:
    first_number = input("\nInput first number.")
    if first_number =='q':
        break
    second_number = input("\nInput second number.")
    if second_number =='q':
        break

    try:
        answer = int(first_number)/int(second_number)
    except ZeroDivisionError:
        print("You can't divide by 0!")
    else:
        print(answer)

#处理FileNotFoundError
filename = 'alice.txt'
try:
    with open(filename, encoding='utf-8') as f:
        contents = f.read()
except FileNotFoundError:
    print(f"Sorry, the {filename} does not exist.")

#分析文本
title = 'Alice in Wonderland'
print(title.split())

#存储数据
numbers = [2, 3, 5, 7, 11, 13]
filename = 'numbers.json'
with open(filename,'w') as f:
    json.dump(numbers,f)   #将数字列表存储到文件中
#将json里面的内存读取到文件中
with open(filename) as f:
    numbers = json.load(f)

print(numbers)

#保存和读取用户生成的数据
username = input("What is your name?")
filename = 'username.json'
with open(filename, 'w') as f:
    json.dump(username,f)
    print(f"We'll remember you when you come back, {username}")

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

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

def greet_user():
    username = get_stored_username()
    if username:
        print(f"Welcome back, {username}")
    else:
        username = get_new_username()
        print(f"We'll remember when you come back, {username}")

greet_user()