python 学习第5天

字典增删改查

dic1 ={"name":"春生","age":18,"sex":"male"}
# dic1["asdas"]="dfdsf"  添加  默认最后一个
# print(dic1)
# dic1["age"]=20      //    如果有建 则值覆盖
# print(dic1)
#
# dic1.setdefault("weight")  //有建值对  不做任何改变  没有添加建值对
#dic1.setdefault("weight",150)  // 添加建值对
#print(dic1)
# dic1.setdefault("5","5")
# print(dic1)



#删

# print(dic1.pop("name"))  ///有 返回值  按建去删除
#print(dic1.pop("sss","None"))  #//可设置返回值
#print(dic1)


#print(dic1.popitem())  #随机删除  有返回值   元组里面是删除的建值

# del dic1["name"]
# print(dic1)

# del dic1     //删除列表 会报错
# print(dic1)


# dic1.clear()     //清空 列表
# print(dic1)

#改


# dic1["name"]=1          #     //  按建  去改
# print(dic1)

# dic={"name":"jinag","age":"50","sex":"male"}
# dic2={"name":"alex","weight":75}
# dic.update(dic2)        #   /////  update 改
# print(dic)
# print(dic2)

#结果：
# {‘name‘: ‘jinag‘, ‘age‘: ‘50‘, ‘sex‘: ‘male‘}
# {‘name‘: ‘jinag‘, ‘weight‘: 75, ‘age‘: ‘50‘, ‘sex‘: ‘male‘}

#查
#print(dic1.keys())      #//建
#print(dic1.values())     //值
#print(dic1.items())         //是一个列表 里面是元祖  dict_items([(‘name‘, ‘春生‘), (‘age‘, 18), (‘sex‘, ‘male‘)])
#
# for i in dic1:
#     print(i)             //    查  建
#  for i in dic1.keys():
#     print(i)

# for i in dic1.values():    //   查  值
#     print(i)


#面试题
# a,b=1,2
# a=1
# b=2
# a,b=b,a
# print(a,b)

字典 嵌套 

用建去找  

在去增删改查