python 学习day5

# 转码之间必须先转回至Unicode,在python2.X中默认是ASCII编码,在Python3中默认就是unicode编码
# 编码详解两篇文章：http://www.cnblogs.com/luotianshuai/articles/5735051.html
# http://www.cnblogs.com/yuanchenqi/articles/5956943.html
import sys
print(sys.getdefaultencoding())

s='我爱北京'
print(s)
print(s.encode())  #utf-8 编码

s_gbk =s.encode(encoding='gbk')  #utf-8转换为gbk
print(s_gbk)

gbk_utf =s_gbk.decode(encoding='gbk').encode(encoding='utf-8')  #gbk转换为utf-8
print(gbk_utf)
print(gbk_utf.decode(encoding='utf-8'))  #将utf-8解码


# #-*- coding:utf-8 -*-
#
# tim = '天帅'
# #转为UTF-8编码
# print(tim.encode('UTF-8'))
# #转为GBK编码
# print(tim.encode('GBK'))
# #转为ASCII编码(报错为什么?因为ASCII码表中没有‘天帅’这个字符集~~)
# print(tim.encode('ASCII'))

while True:
    a = input("FN:")
    if a=='q':
        break
    b = input("SN:")
    if b=='q':
        break
# 处理异常方式，有时候用pass处理异常
    try:
        answer=int(a)/int(b)
    except ZeroDivisionError:
        print('不能除以0')
    else:
        print(answer)

import json

Nums = [1,7,8,1,10,6]


f_name = '_list.json'  #一般文件存储都用JSON格式
with open(f_name,'w') as f:
    json.dump(Nums,f)  #存储数据

with open(f_name) as f:
    nums = json.load(f)  #读取数据
print(nums)

# 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且进行存储

f_name = 'username.json'
try:
    with open(f_name) as f:
        username = json.load(f)
except FileNotFoundError:
    username = input("please input your username:")
    with open(f_name,'w') as f:
        json.dump(username,f)
        print("We'll remember you when you come back"+"username"+"!")
else:
    print("Welcome back,"+username+"!")

# 重构
def get_stored_username():
    '''如果存储了用户名，就直接获取它'''
    f_name = 'username1.json'
    try:
        with open(f_name) as f:
            username = json.load(f)
    except FileNotFoundError:
        return None
    else:
        return  username

def get_new_username():
    '''提示用户输入用户名'''
    f_name = 'username1.json'
    username = input("please input your username:")
    with open(f_name, 'w') as f:
        json.dump(username, f)
    return username

def greet_user():
    '''问候用户，并指出其用户名'''
    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()