第一部分day4-三次登录实验、字符编码

#-----三次登录实验-----

 memu = {
     "陕西":{
         "西安市":{
             "新城区":["大明宫遗址","含元殿遗址","八路军办事处"],
             "碑林区":["安碑林博物馆","明城墙","小雁塔" ],
             "莲湖区":["钟鼓楼","明城墙","西安都城隍庙""西安清真大寺"],
             "雁塔区":["秦二世胡亥墓","大兴善寺","大雁塔","曲江池","陕西历史博物馆"],
             "未央区":["秦阿房宫","汉未央宫","唐大明宫"],
             "蓝田":["华胥故里","水陆庵","王顺山","汤峪","蓝田人遗址"]
         },
         "汉中市":{
             "南郑":["红寺湖风景区","黎平国家森林公园","汉山广场"],
             "城固":["张骞纪念馆","南沙湖风景区","桔园景区"],
             "洋县":["开元舍利塔"],
             "佛坪":["大坪屿风景区","佛坪县自然保护区"]
         }
     },
     "重庆市":{
         "渝中区":["解放碑","朝天门","洪崖洞","若瑟堂"],
         "万州区":["万州大瀑布","青龙瀑布","天生城","铁峰山国家森林公园"],
         "涪陵区":["白鹤梁","大木花谷","武陵山大裂谷","816核军工洞"],
         "大渡口":["小南海温泉","中华美德公园","金色蛋糕梦幻王国"],
         "江北区":["观音桥","铁山坪森林公园","金源方特科幻公园"]
     }
 }

 current_layer = memu
 parent_layer = []
 while True:
     for key in current_layer:
         print(key)
     choice = input(">>>:").strip()
     if len(choice) == 0 : continue
     if choice in current_layer:
         parent_layer.append(current_layer)
         try:
             if current_layer[choice]:
                 current_layer = current_layer[choice]
         except Exception:
             print("输入错误,请重新输入！".center(50,'-'))
             continue
     elif choice == 'b':
         try:
             if current_layer:
                 current_layer = parent_layer.pop()
         except Exception:
             print("已返回首页目录".center(50,'-'))

     else:
         print("无此项目")

#-----字符编码-----

#-----中国字符编码发展-----
ASCII :只能存英文和拉丁字符，一个字符占一个字符，8位
GB2312:GB 2312 标准共收录 6763 个汉字
GBK:GBK 共收入 21886 个汉字和图形符号
GB18030:GB 18030 与 GB 2312-1980 和 GBK 兼容，共收录汉字70244个

unicode:utf-32:一个字符占4个字节
unicode:utf-16:一个字符占2个字节或2个以上
unicode:utf-8:一个英文用ASCII码来存储，一个中文占3个字节

#-----in python2-----
UTF-8 --decode-->Unicode--encode-->GBK
GBK--decode-->Unicode--encode-->UTF-8

#测试环境为python2,在Windows 客户端（GBK编码）运行

 a = "棒极了"
 gbk_to_unicode = a.decode("utf-8")
 print(a) #妫掓瀬浜
 utf8_to_unicode = gbk_to_unicode.encode("gbk")
 print(gbk_to_unicode) #棒极了
 print(utf8_to_unicode)#棒极了

#-----in python3 -----
字符默认编码Unicode ，文件默认编码UTF-8
encode 在编码同时，会把数据转成bytes 类型
decode 在解码同时，会把数据转成字符串
b = byte = 字符类型= [0-255]