1.声明个电脑类: 属性:品牌、颜、内存小 方法:打游戏、写代码、看视频

a.创建电脑类的对象，然后通过对象点的方式获取、修改、添加和删除它的属性

b.通过attr相关方法去获取、修改、添加和删除它的属性

class Computer:
    """电脑类"""
    def __init__(self, brand1, color1, memory1):
        self.brand = brand1
        self.color = color1
        self.memory = memory1

    def play_games(self):
        print('打游戏')

    def write_code(self):
        print('写代码')

    def watch_video(self):
        print('看视频')


computer1 = Computer('lenovo', '白色', '4g')
computer_color = computer1.color
computer1.brand = 'apple'
computer1.size = '15.4'
del computer1.memory

getattr(computer1, 'brand')
setattr(computer1, 'brand', '华硕')
setattr(computer1, 'price', 5000)
delattr(computer1, 'color')

2.声明个人的类和狗的类:

狗的属性:名字、颜色、年龄

狗的方法:叫唤

人的属性:名字、年龄、狗

人的方法:遛狗

a.创建人的对象小明，让他拥有一条狗大黄，然后让小明去遛大黄

class Person:
    """人的类"""
    def __init__(self, name, age, dog):
        self.name = name
        self.age = age
        self.dog = dog

    def walk_dog(self):
        print('%s遛狗' % self.name)


class Dog:
    """狗的类"""
    def __init__(self, dog_name, color, dog_age):
        self.dog_name = dog_name
        self.color = color
        self.dog_age = dog_age

    def yelp(self):
        print('%s叫唤' % self.dog_name)


dog1 = Dog('小黄','黄色', 3)
person = Person('小明', 23, '小黄')

person.walk_dog()

3.声明一个圆类，自己确定有哪些属性和方法

import math


class Circle:
    """圆的类"""
    def __init__(self, R, D):
        self.R = R
        self.D = D

    def acreage(self):
        return math.pi * self.R**2

    def perimeter(self):
        return math.pi * self.D

4.创建一个学生类:

属性:姓名，年龄，学号

方法:答到，展示学生信息

创建一个班级类:

属性:学生，班级名

方法:添加学生，删除学生，点名, 求班上学生的平均年龄

class Student:
    """学生类"""
    def __init__(self, name, age, stu_id):
        self.name = name
        self.age = age
        self.stu_id = stu_id

    def answer(self):
        print(self.name, '到', sep='')

    def show_message(self):
        print(self.__dict__)


stu1 = Student('小明', 20, '001')
stu1.show_message()
stu1.answer()


class Class:
    """班级类"""
    def __init__(self, students: list, class_name=''):
        self.students = students
        self.class_name = class_name

    def add_stu(self, student):
        return self.students.append(student)

    def del_stu(self, student):
        self.students.remove(student)

    def count_stu(self):
        for dict in self.students:
            print(dict['name'])

    def average_age(self):
        sum_age = 0
        count = 0
        for dict in self.students:
            sum_age += dict['age']
            count += 1
        print(sum_age/count)