字典

# 字典是以键值对key-value形式存在
#key不允许重复
# 字典声明
dict1={}
dict2={"name":"Lisa","age":18,"address":"Beijing"}

#赋key值
dict={}
dict1=dict.fromkeys(['name','age','gender'],'N/A')
print(dict1)
{'name': 'N/A', 'age': 'N/A', 'gender': 'N/A'}

# 根据key取值
print(dict2.get("name"))
get 可以为不存在的键赋值
print(dict1.get('age', 18))

# 打印所有key
print(dict2.keys())
for key in dict2.keys():
    print(key)

# 打印所有value
print(dict2.values())
for value in dict2.values():
    print(value)

# 遍历key 取值
for key in dict2:
    value=dict2[key]
    print(value)

# 取key,value
for key,value in dict2.items():
    print(key,value)

# 更新
dict2["age"]=19
# 删除
dict2.pop("address")
# 删除最后一对key-value
dict2.popitem()
print(dict2.items())

字典也称哈希

hash(key)散列值存在内存