Python三级菜单实现（字典 && 文件）

实现省市县三级联动

要求：

• 打印三级菜单

• 可返回上一级

• 可随时退出程序

1.使用字典实现

	dic={
	    "安徽":{
	        "六安":{
	              "金寨":[],
	            "舒城":[],
	            "霍山":[],
	            "霍邱:[]"},
	        "淮南":{
	            "田家庵":[],
	            "凤台":[],
	            "寿县":[]
	        }
	    },
	    "江苏":{
	        "无锡":{
	            "宜兴":[],
	            "江阴":[]
	        },
	        "南京":{
	            "鼓楼":[],
	            "玄武":[],
	            "雨花":[]
	        },
	    },
	}
	#保存当前层，保持动态循坏
	current_layer = dic
	#保存所有父级循环
	parent_layers = []
	exit_flag = True
	while exit_flag:
	        for key in current_layer:
	                print(key)
	        choice = input("<<<<").strip()
	        if len(choice) == 0: continue
	        if choice in current_layer:
	            #当前层加到父层列表
	                parent_layers.append(current_layer)
	                #进入下一层
	                current_layer = current_layer[choice]
	        elif choice=='b':
	                if parent_layers:
	                #取出父级
	                        current_layer = parent_layers.pop()
	        elif choice == 'q':
	                exit_flag = False
	                print(".....end......")
	        else:
	                print("无此项")

2.以文件存储形式实现

（1）data文件内容

{'Anhui': {'Hefei': {'FeiDong'}, 'Huainan': {'Feitai'}}, 'Tianjin': {}, 'Beijing': {'Feitai': {'B2'}, 'Chaoyang': {'B1'}}}

（2）代码实现

• 打印三级菜单
• 能实现增删改查
• 可返回上一级
• 可随时退出程序

# __author__: "Betsy Kudo"
# date: 2019/1/9
with open("data", "r", encoding="utf-8") as fr:
    data = fr.readline().strip()
    # 转换为字典
    dic = eval(data)
    # 保存当前层，保持动态循坏
    current_layer = dic
    # 保存所有父级循环
    parent_layers = []
    layer_num = 0
    exit_flag = True
    while exit_flag:
        print("------------********----------")
        for key in current_layer:
            print(key)
        print("------------********-----------")
        print("[a]增加 [b]返回上一级 [d]删除 [u]修改 [q]停止")
        choice = input("<<<<").strip()
        if len(choice) == 0:
            continue
        if choice in current_layer:
            layer_num += 1
            # 当前层加到父层列表
            parent_layers.append(current_layer)
            # 进入下一层
            current_layer = current_layer[choice]
        # 增
        elif choice == 'a':
            add_data = input("input the data：")
            current_layer[add_data] = {}
        elif choice == 'b':
            if parent_layers:
                layer_num -= 1
                # 取出父级
                current_layer = parent_layers.pop()
            else:
                print("已是最上级")

        # 删
        elif choice == 'd':
            del_data = input("input the data：")
            if del_data in current_layer:
                del current_layer[del_data]
            else:
                print("无法删除不存在的数据")
        # 改
        elif choice == 'u':
            old_data = input("input the old data：")
            new_data = input("input the new data：")
            if old_data in current_layer:
                current_layer[new_data] = current_layer.pop(old_data)
        # 退出
        elif choice == 'q':
            exit_flag = False
            print(".....end......")
        else:
            print("无此项")

with open("data", "w", encoding="utf-8") as fw:
    # 更新文件内容
    fw.write(str(current_layer))
    fw.flush()