# 增加/修改
# 如果key存在，就是修改值
# 如果key不存在，就是新增key和value

dict = {"name":"刘备", "age":"15"}
dict["name"] = "关羽"
print(dict)

dict["class"] = "1班"
print(dict)

 

# 删除  一旦key删除了，则value也删除了
dict = {"name":"刘备", "age":"15"}
dict.pop("name")
print(dict)

 

# 清空
dict = {"name":"刘备", "age":"15"}
dict.clear()
print(dict)

 

# 得到key对应的值
dict = {"name":"刘备", "age":"15"}
a = dict["name"]
print(a)

 

dict = {"name":"周瑜", "age":"32", "id":"001"}
dict["sex"] = "男"
dict.pop("id")
dict["age"] = "26"
print(dict)

 

# 遍历字典
dict = {"name":"周瑜", "age":32, "id":"001"}
for n in dict:
    print(n, dict[n])
#     key n  dict[n] value

 

# 通过items遍历字典
# 字典.items()返回一个包含key和value的元组

dict = {"name":"周瑜", "age":32, "id":"001"}
# for n in dict.items():
#     print(n)

# 一旦使用了字典的items方法， n就是一个包含了key和value的元组

for n in dict.items():
    # 对一个元组进行拆包
    a, b = n
    print(a, b)

 

dict1 = {
    "a":23,
    "b": 4,
    "c": 9,
    "d": 3,
    "e": 12
}


# for i in dict1:
#     print(i, dict1[i])

print("-------")
for a, b in dict1.items():
    print(a,b)

 

# 显示值9对应的key
dict1 = {
    "a":23,
    "b": 4,
    "c": 9,
    "d": 3,
    "e": 12
}

for n in dict1:
    if dict1[n] == 9:
        print(n)