python基础--5字典

Posted 2021-12-17 tangcode

#字典
#dict
#基本结构
info=
    "k1":‘v1‘ #键值对
    ,"k2":"v2"


#字典的value可以是任何值
# info="k1":18,
#       ‘k2‘:True,
#       ‘k3‘:[11,22,55,"kk1":‘vv1‘,
#                       ‘kk2‘:‘vv2‘,
#                       ‘kk3‘:(11,33,55)],
#       "k4":(1,23)
#       



####,列表,字典不能作为字典的key
# info=1:"asdf",
#       "k1":"asdf",
#       (11,22):123,
#       # True:123
#       #"ll":"hello":123
#       #[11,22]:22
#       
# print(info)


#字典无序
#字典支持del删除
# info="k1":18,
#       ‘k2‘:True,
#       3:"sss",
#       ‘k3‘:[11,22,55,"kk1":‘vv1‘,
#                       ‘kk2‘:‘vv2‘,
#                       ‘kk3‘:(11,33,55)],
#       "k4":(1,23)
#       

#通过索引找到指定元素
# print(info[‘k1‘])
# print(info[3])
#print(info["k3"][3]["kk3"][0])

#字典支持del删除
# del info["k1"]
# print(info)

#for 循环
#dict
info="k1":18,
      ‘k2‘:True,#布尔值(0,1) key值重复则只显示一个
      3:"sss",
      ‘k3‘:[11,22,55,"kk1":‘vv1‘,
                      ‘kk2‘:‘vv2‘,
                      ‘kk3‘:(11,33,55)],
      "k4":(1,23)
      


# for item in info.values():
#     print(item)

# for item in info.keys():
#     print(item)

# for k,v in info.items():
#     print(k,v)


# num="k1" in info
# print(num)


############
#字典
#dict


#根据序列,创建字典,指定统一的值!!!
# v=dict.fromkeys([11,22,33],"han")
# print(v)

#根据Key获取值,key不存在是,可以指定默认值(None)
dic="item":1,"k1":1222
# n=dic.get("item11")
# print(n)


#删除并获取值
# v=dic.pop("k1")
# print(dic,v)

# v=dic.popitem()
# print(dic,v)


#设置值,如果已经存在,不设置,获取当前key对应的值
#不存在,设置,获取当前key对应的值
# v=dic.setdefault("k12","han")
# print(dic,v)


#更新
#dic.update(‘k1‘:1111,"k3":12223)
dic.update(k1=123,k3=2553)#**kwargs
print(dic)


#keys() ,values()  ,items() ,get()  ,update


#字典的in方法
# v=1 in dic.values()
# print(v)



#布尔值
#0,1
#0 ,‘‘,None,,(),[] ==> False