1.声明⼀个电脑类: 属性:品牌、颜⾊、内存⼤小 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.的方式获取、修改、添加和删除它的属性
b.通过attr相关⽅方法去获取、修改、添加和删除它的属性

class Computer:
    def __init__(self, brand1, color1,memorySize1):
        self.brand = brand1
        self.color = color1
        self.memorySize = memorySize1

    def playing_games(self):
        print('%s电脑适合打游戏' % self.brand)


    def writing_codes(self):
        print('%s电脑适合写代码' % self.brand)


    def watching_videos(self):
        print('%s电脑适合看视频' % self.brand)

# a.创建电脑类的对象，然后通过对象.的方式获取、修改、添加和删除它的属性
computer1 = Computer('ThinkPad','黑色','8g')
print(computer1.brand)  # 查

computer1.brand = '外星人'  # 改
computer1.playing_games()

computer1.price = '10000元'  # 增
print(computer1.price)

del computer1.price   #  删
# print(computer1.price)  AttributeError: 'Computer' object has no attribute 'price'


# b.通过attr相关⽅方法去获取、修改、添加和删除它的属性
computer2 = Computer('Apple', '银色', '16g')
computer2.writing_codes()
print(getattr(computer2, 'color'))              # 查
print(getattr(computer2, 'price', '无价格'))

setattr(computer2, 'color','金色')                # 改
print(computer2.color)

setattr(computer2, 'price','8000元')             # 增
print(computer2.price)

delattr(computer2,'price')
# print(computer2.price)              AttributeError: 'Computer' object has no attribute 'price'

2.声明⼀个人的类和狗的类:
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 Human:
    def __init__(self,name1,age1,dog1):
        self.name = name1
        self.age = age1
        self.dog = dog1

    def walk_dog(self):
        print('%s牵着%s在公园散步' % (self.name, self.dog))


class Dog:
    def __init__(self, name1,color1,age1):
        self.name = name1
        self.color = color1
        self.age = age1

    def bark(self):
        print('%s在乱叫' % self.name)


human1 = Human('小明', '18', '大黄')
dog1 = Dog('大黄','黄色', '3')
human1.walk_dog()

3.声明⼀一个圆类，自己确定有哪些属性和方法

import math
class Circle:
    # 定义属性：半径和圆心角
    def __init__(self,radius, angle):
        self.radius = radius
        self.angle = angle
    # 函数：求圆的周长
    def perimeter(self):
        return round(2 * math.pi * self.radius,2)

    # 函数：求圆的面积
    def area(self):
        return round(math.pi * self.radius ** 2,2)

    # 函数：求弧长
    def length(self):
        return round(math.pi * self.angle * self.radius / 180,2)


circle1 = Circle(10, 360)
print(circle1.perimeter())
print(circle1.area())
print(circle1.length())

4.创建一个学生类:
属性:姓名，年龄，学号
方法:答到，展示学⽣生信息
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

import json
class Students:
    def __init__(self, name, age=0, stu_id=1):
        self.name = name
        self.age = age
        self.stu_id = stu_id
    # 答到
    def achieve(self):
        print('%s到' % self.name)
    # 获取学生信息，生成字典
    def information(self):
        stu_dict = {'姓名':self.name, '年龄':self.age, '学号':self.stu_id}
        return stu_dict


class Class_stu:
    def __init__(self, students,class_name):
        self.students = students
        self.class_name = class_name
        # 生成器生成学号，通过列表的长度来确定每次执行程序时学号的初始值
        self.stu_id = ('stu' + str(num).zfill(3) for num in range(len(students)+1,100))



    # 添加学生
    def add_stu(self):
        while True:
            print('1.添加学生\n2.返回')
            value = input('请选择（1-2）')
            if value == '1':
                stu_name = input('输入姓名')
                stu_age = input('输入年龄')
                stu_id = next(self.stu_id)  # 生成器获取学号
                stu = Students(stu_name,stu_age,stu_id).information()  # 调用Students类中的方法来保存学生信息
                self.students.append(stu)       # 将学生信息添加至列表
            else:
                break
        with open('test.json', 'w',encoding='utf-8') as f:
                f.write(json.dumps(self.students))          # 将学生信息写入文件

# 删除学生
    def delete_stu(self):
        name1 = input('请输入要删除的学生名字：')
        for i in students:
            if i['姓名'] == name1:
                students.remove(i)
                break
        else:
            print('无此人')
        for j in range(len(students)):
            students[j]['学号'] = 'stu' + str(j+1).zfill(3)       # 重新生成学号
        with open('test.json', 'w',encoding='utf-8') as f:
                f.write(json.dumps(self.students))                  # 重新写入学生信息

# 点名
    def call_stu(self):
        name1 = input('请输入要点的学生名字：')
        for i in students:
            if i['姓名'] == name1:
                Students(name1).achieve()       # 调用Students类中的方法
                break
        else:
            print('无此人')

# 求平均年龄
    def ave_age(self):
        sum1 = 0
        for i in students:
            sum1 += int(i['年龄'])
        aver = round(sum1 / len(students),2)
        print('平均年龄为：',aver)


# 读取主界面
def show_mainpage():
    with open('test.txt', encoding='utf-8') as f:
        page = f.read()
        print(page)


#  主程序
with open('test.json',encoding='utf-8') as f:
    students = json.loads(f.read())
c1 = Class_stu(students,'py1902')
while True:
    show_mainpage()
    value = input('请选择（1-5）')
    if value == '1':
        c1.add_stu()
    elif value == '2':
        c1.delete_stu()
    elif value == '3':
        c1.call_stu()
    elif value == '4':
        c1.ave_age()
    else:
        break