字典----增删改查遍历

#增加字典值

方法一：

massage = {"name":wade,"age":30,"hobby":["girl","book","money"]}

massage["work"]="程序猿"

print(massage)

方法二：

dict1 = massage.setdefault("work","程序猿")

print(dict1)

#该方法拥有返回值！

#当增加的元素key值存在时，返回值为原始值

dict1 = massage.setdefault("name","james")

print(dict1)    #返回值为wade

#当增加的元素可以值不存在时，返回值为value

dict1 = massage.setdefault("city","XIAN")

print(dict1)    #返回值为XIAN

#查

massage = {"name":wade,"age":30,"hobby":["girl","book","money"]}

dic1 = massage["name"]          #通过键查找

dic2 = massage.keys()            #查看所有的键，该方法返回的是一个列表键类型的数据，如需使用必须转换成list类型

print(list(massage.keys()))

dic3 = massage.values()        #查看所有的值

print(dic3)

dic4 = massage.items()          #查看所有的键值对，结果以列表形式返回，列表内的键值对以元祖形式存储

print(dic4)

#改 

massage = {"name":wade,"age":30,"hobby":["girl","book","money"]}

massage["name"] = "James"

massage2 = {"address":"XIAN","work":"IT","age":29}

massage.update(massage2)              #将massage2中数据加入到massage中，若有重复数据，则覆盖massage中的数据

print(massage)

#删

massage = {"name":wade,"age":30,"hobby":["girl","book","money"]}

del massage                          #删除字典

del(massage["name"])             #删除指定的键值对

massage.clear()                    #清空列表

massage.pop("name")           #有返回值，返回值为成功删除的值

massage.popitem()                #随机删除一组键值对

#排序           按照键的数序（ASCII码）排列

dic = {5:"555",2:"666",4:"44"}

print(sorted(dic))

for循环遍历

dic1 = {"name":"wade","age":18,"address":"xian"}

for i in dic1

　　print(i,dic1[i])

获取字典的所有key

dic = {5:"555",2:"666",4:"44"}

keys = dic.keys()

print(type(keys))             

注：此处获得的key并非列表，而是<class 'dict_keys'>类型，如需获取其中值必须使用list()方法强转