Python 字典

dic = {'name':'jin','age':18,'sex':'male'}
print(dic)#{'name': 'jin', 'sex': 'male', 'age': 18}

##第一种:有则覆盖，无则添加
# dic = {'name':'jin','age':18,'sex':'male'}
# dic['hobby'] = 'girl'
# print(dic)

# dic['name'] = 'wusir'
# print(dic)
#{'age': 18, 'sex': 'male', 'name': 'wusir'}

dic = {'name':'jin','age':18,'sex':'male'}
# dic.setdefault('hobby')
# print(dic)#{'sex': 'male', 'hobby': None, 'age': 18, 'name': 'jin'}
#'hobby'是键，而不是值，所以字典里会出现'hobby':None
# dic.setdefault('hobby','girl')
# print(dic)#{'name': 'jin', 'hobby': 'girl', 'age': 18, 'sex': 'male'}
#键值对 'hobby':girl添加到字典了、原字典没有hobby
# dic.setdefault('name','ritian')
# print(dic)#{'age': 18, 'name': 'jin', 'sex': 'male'}
#原字典中有k,name'所以不变

#pop  有返回值
# dic = {'name':'jin','age':18,'sex':'male'}
# print(dic.pop('age'))##返回所删除键值对的age值18
# print(dic)
# dic.pop('hobby')##报错
# print(dic.pop('hobby',None))##设定返回的键值，当hobby不存在时，返回None

##clear 清空
# dic = {'name':'jin','age':18,'sex':'male'}
# dic.clear()
# print(dic)#{}清空字典里面所有键值对

##del
# dic = {'name':'jin','age':18,'sex':'male'}
# del dic
# print(dic)#NameError: name 'dic' is not defined,通过del dic,已删除字典dic

# dic = {'name':'jin','age':18,'sex':'male'}
# del dic['name']
# print(dic)#{'age': 18, 'sex': 'male'},删除dic里面‘name’的键值对

# dic = {'name':'jin','age':18,'sex':'male'}
# print(dic.popitem())
# print(dic)#每次随机删除dic里面的键值对

# dic = {"name":"jin","age":18,"sex":"male"}
# dic['name'] = '太白'
# print(dic)#{'name': '太白', 'sex': 'male', 'age': 18}更改键name的值
# 两个字典的改
# dic = {"name":"jin","age":18,"sex":"male"}
# dic2 = {"name":"alex","weight":75}
# dic2.update(dic)#将dic键值对，覆盖并添加到dic2
# print(dic)#{'age': 18, 'name': 'jin', 'sex': 'male'}
# print(dic2)#{'age': 18, 'sex': 'male', 'name': 'jin', 'weight': 75}

# dic = {"name":"jin","age":18,"sex":"male"}

# print(dic['name'])#jin 查键所对应的值jin
# print(dic['name1'])#KeyError: 'name1'如果查看没有的键，则会显示错误信息
# print(dic.get('name'))#jin
# print(dic.get('name1'))#没有此键时默认返回None
# print(dic.get('name1','无此键值对'))#无此键值对,后面可以设置···

#key() values()  item()
dic = {"name":"jin","age":18,"sex":"male"}
# print(dic.keys(),type(dic.keys()))#查看dic的键keys
# print(dic.keys())#
# for i in dic.keys():
#     print(i)

# for i in dic:
#     print(i)

# li = list(dic.keys())#以列表的形式查看dic键
# print(li)
# print(dic.values())#值

# for i in dic.values():#列出dic的键值
#     print(i)
#
#items 随机打出dic的键值对

# print(dic.items())#打出dic的键值对，顺序随机
#dict_items([('age', 18), ('sex', 'male'), ('name', 'jin')])

# for i in dic.items():#
#         print(i,type(i))
# ('name', 'jin') <class 'tuple'>
# ('sex', 'male') <class 'tuple'>
# ('age', 18) <class 'tuple'>