day 13 字典dict 操作

1.len   键值对的个数

In [4]: nums = [11,22,33]

In [6]: len(nums)
Out[6]: 3

In [7]: infor = {"name":"alex","age":14}   #键值对是1个整体

In [8]: len(infor)
Out[8]: 2

2.keys  vaules items

###  python2

In [1]: infor = {"name":"alex","age":18}

In [3]: infor.keys()
Out[3]: ['age', 'name']

In [4]: infor.values()
Out[4]: [18, 'alex']

#查找
In [5]: infor.get("name")
Out[5]: 'alex'

In [6]: infor.get("dfas")

In [7]: if "alex" in infor.values():
   ...:     print("有alex这个值")
   ...:
有alex这个值

#####  python3
In [9]: infor
Out[9]: {'age': 14, 'name': 'alex'}

In [10]: infor.keys()
Out[10]: dict_keys(['age', 'name'])    #是1个对象

In [11]: infor.values()
Out[11]: dict_values([14, 'alex'])

In [14]: infor.items()
Out[14]: dict_items([('age', 14), ('name', 'alex')])  #返回元组

3.遍历

#### python3   遍历keys  vaules  items
In [12]: for temp in infor.keys():
   ....:     print(temp)
   ....:
age
name

In [13]: for temp in infor.values():
   ....:     print(temp)
   ....:
14
alex

In [15]: for temp in infor.items():
   ....:     print(temp)
   ....:
('age', 14)
('name', 'alex')

In [16]: for temp in infor.items():
   ....:     print("key:%s,value:%s"%(temp[0],temp[1]))
   ....:
key:age,value:14
key:name,value:alex

### 元组拆包  遍历
In [17]: for A,B in infor.items():
   ....:     print("key:%s,value:%s"%(A,B))
   ....:
key:age,value:14
key:name,value:alex

　　　　元组拆包