字典 dict

Posted 2020-11-27 yyxx8888

• 索引
• 长度
• for循环

 

user_info = {"name":3,"age":11,"country":"china"}
print(user_info["country"])
print(len(user_info))
for k in user_info:
    print(k)


china
3

name
country
age

• 所有的keys
• 所有的values
• 所有的keys，values

user_info = {"name":"Amy","age":11,"country":"china"}
print(user_info.keys())
print(user_info.values())
print(user_info.items())



dict_keys([‘country‘, ‘age‘, ‘name‘])
dict_values([‘china‘, 11, ‘Amy‘])
dict_items([(‘country‘, ‘china‘), (‘age‘, 11), (‘name‘, ‘Amy‘)])

• 　　for循环

for k,v in user_info.items():
    print(k)



age
country
name

　　

for k,v in user_info.items():
    print(v)



11
china
Amy

　　

for k,v in user_info.items():

    print(k,v)



name Amy
country china
age 11

　　其他方法：

• 1、clear

user_info = {"name":"Amy","age":11,"country":"china"}
user_info.clear()
print(user_info)



{}

　　

 

• 2、copy

 

• 3、get  获取一个不存在key，get返回none，如果通过索引获取一个不存在的key，则报错；

user_info = {"name":"Amy","age":11,"country":"china"}
print(user_info.get("age"))
print(user_info.get("sss"))


11
None