查看多级目录 –需求– 1.使用字典嵌套建立三级目录 2.输入各级分目录可以逐级显示 3.按‘b’返回上一层，按‘q’退出程序
–program summary– 1.字典嵌套多级目录 2.for循环输出字典的键 3.if条件判断输入是否在字典键中 4.while循环确保按’b’返回上一层 5.exit_flag确保按‘q’随时退出
–Code–
# Author:sdtvpengl data = { '北京':{ "昌平":{ "沙河":["oldboy","test"], "天通苑":["链家地产","我爱我家"] }, "朝阳":{ "望京":["奔驰","陌陌"], "国贸":{"CICC","HP"}, "东直门":{"Advent","飞信"}, }, "海淀":{}, }, '山东':{ "德州":{}, "青岛":{}, "济南":{} }, '广东':{ "东莞":{}, "常熟":{}, "佛山":{}, }, } exit_flag = False #实现在任何一级自由退出 while not exit_flag: for i in data: print(i) choice = input('输入选择1>>:') if choice in data: while not exit_flag: #不循环无法返回上一层 for i2 in data[choice]: print('\t',i2) #打印tab格式输出 choice2 = input('输入选择2>>:') if choice2 in data[choice]: while not exit_flag: for i3 in data[choice][choice2]: print('\t\t',i3) choice3 = input('输入选择3>>：') if choice3 in data[choice][choice2]: for i4 in data[choice][choice2][choice3]: print('\t\t\t',i4) choice4 = input('输入‘b’返回>>:') if choice4 == 'b': pass elif choice4 == 'q': exit_flag = True if choice3 == 'b': #每一级都可b返回 break elif choice3 == 'q': exit_flag = True if choice2 == 'b': #每一级都可b返回 break elif choice2 == 'q': exit_flag = True